{"id":1382,"date":"2018-08-11T02:48:26","date_gmt":"2018-08-11T02:48:26","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/suny-mcc-introductorychemistry\/?post_type=chapter&#038;p=1382"},"modified":"2018-08-11T03:06:22","modified_gmt":"2018-08-11T03:06:22","slug":"formula-mass","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-mcc-introductorychemistry\/chapter\/formula-mass\/","title":{"raw":"5.3 Formula Mass","rendered":"5.3 Formula Mass"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Objectives<\/h3>\r\nBy the end of this section, you will be able to:\r\n<ul>\r\n \t<li>Calculate formula masses for covalent and ionic compounds<\/li>\r\n<\/ul>\r\n<\/div>\r\nWe can argue that modern chemical science began when scientists started exploring the quantitative as well as the qualitative aspects of chemistry. For example, Dalton\u2019s atomic theory was an attempt to explain the results of measurements that allowed him to calculate the relative masses of elements combined in various compounds. Understanding the relationship between the masses of atoms and the chemical formulas of compounds allows us to quantitatively describe the composition of substances.\r\n<h2>Formula Mass<\/h2>\r\nIn an earlier chapter, we described the development of the atomic mass unit, the concept of average atomic masses, and the use of chemical formulas to represent the elemental makeup of substances. These ideas can be extended to calculate the <strong>formula mass <\/strong>of a substance by summing the average atomic masses of all the atoms represented in the substance\u2019s formula.\r\n<h3>Formula Mass for Covalent Substances<\/h3>\r\nFor covalent substances, the formula represents the numbers and types of atoms composing a single molecule of the substance; therefore, the formula mass may be correctly referred to as a molecular mass. Consider chloroform (CHCl<sub>3<\/sub>), a covalent compound once used as a surgical anesthetic and now primarily used in the production of the \u201canti-stick\u201d polymer, Teflon. The molecular formula of chloroform indicates that a single molecule contains one carbon atom, one hydrogen atom, and three chlorine atoms. The average molecular mass of a chloroform molecule is therefore equal to the sum of the average atomic masses of these atoms. Figure 1 outlines the calculations used to derive the molecular mass of chloroform, which is 119.37 amu.\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"880\"]<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211111\/CNX_Chem_03_01_chloroform1.jpg\" alt=\"A table and diagram are shown. The table is made up of six columns and five rows. The header row reads: \u201cElement,\u201d \u201cQuantity,\u201d a blank space, \u201cAverage atomic mass (a m u),\u201d a blank space, and \u201cSubtotal (a m u).\u201d The first column contains the symbols \u201cC,\u201d \u201cH,\u201d \u201cC l\u201d and a blank, merged cell that runs the width of the first five columns. The second column contains the numbers \u201c1,\u201d \u201c1,\u201d and \u201c3\u201d as well as the merged cell. The third column contains the multiplication symbol in each cell except for the last, merged cell. The fourth column contains the numbers \u201c12.01,\u201d \u201c1.008,\u201d and \u201c35.45\u201d as well as the merged cell. The fifth column contains the symbol \u201c=\u201d in each cell except for the last, merged cell. The sixth column contains the values \u201c12.01,\u201d \u201c1.008,\u201d \u201c106.35,\u201d and \u201c119.37.\u201d There is a thick black line below the number 106.35. The merged cell under the first five columns reads \u201cMolecular mass.\u201d To the left of the table is a diagram of a molecule. Three green spheres are attached to a slightly smaller black sphere, which is also attached to a smaller white sphere. The green spheres lie beneath and to the sides of the black sphere while the white sphere is located straight up from the black sphere.\" width=\"880\" height=\"216\" \/> Figure 1. The average mass of a chloroform molecule, CHCl<sub>3<\/sub>, is 119.37 amu, which is the sum of the average atomic masses of each of its constituent atoms. The model shows the molecular structure of chloroform.[\/caption]\r\n\r\nLikewise, the molecular mass of an aspirin molecule, C<sub>9<\/sub>H<sub>8<\/sub>O<sub>4<\/sub>, is the sum of the atomic masses of nine carbon atoms, eight hydrogen atoms, and four oxygen atoms, which amounts to 180.15 amu (Figure 2).\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"880\"]<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211113\/CNX_Chem_03_01_aspirin1.jpg\" alt=\"A table and diagram are shown. The table is made up of six columns and five rows. The header row reads: \u201cElement,\u201d \u201cQuantity,\u201d a blank space, \u201cAverage atomic mass (a m u),\u201d a blank space, and \u201cSubtotal (a m u).\u201d The first column contains the symbols \u201cC,\u201d \u201cH,\u201d \u201cO,\u201d and a merged cell. The merged cell runs the length of the first five columns. The second column contains the numbers \u201c9,\u201d \u201c8,\u201d and \u201c4\u201d as well as the merged, cell. The third column contains the multiplication symbol in each cell except for the last, merged cell. The fourth column contains the numbers \u201c12.01,\u201d \u201c1.008,\u201d and \u201c16.00\u201d as well as the merged cell. The fifth column contains the symbol \u201c=\u201d in each cell except for the last, merged cell. The sixth column contains the values: \u201c108.09,\u201d \u201c8.064,\u201d \u201c64.00,\u201d and \u201c180.15.\u201d There is a thick black line below the number 64.00. The merged cell under the first five columns reads \u201cMolecular mass.\u201d To the left of the table is a diagram of a molecule. Six black spheres are located in a six-sided ring and connected by alternating double and single black bonds. Attached to each of the four black spheres is one smaller white sphere. Attached to the farthest right black sphere is a red sphere, connected to two more black spheres, all in a row. Attached to the last black sphere of that row are two more white spheres. Attached to the first black sphere of that row is another red sphere. A black sphere, attached to two red spheres and a white sphere is attached to the black sphere on the top right of the six-sided ring.\" width=\"880\" height=\"216\" \/> Figure 2. The average mass of an aspirin molecule is 180.15 amu. The model shows the molecular structure of aspirin, C<sub>9<\/sub>H<sub>8<\/sub>O<sub>4<\/sub>.[\/caption]\r\n\r\n<div class=\"textbox examples\">\r\n<h3>Example 1: <strong>Computing Molecular Mass for a Covalent Compound<\/strong><\/h3>\r\nIbuprofen, C<sub>13<\/sub>H<sub>18<\/sub>O<sub>2<\/sub>, is a covalent compound and the active ingredient in several popular nonprescription pain medications, such as Advil and Motrin. What is the molecular mass (amu) for this compound?\r\n\r\n[reveal-answer q=\"557459\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"557459\"]\r\n\r\nMolecules of this compound are comprised of 13 carbon atoms, 18 hydrogen atoms, and 2 oxygen atoms. Following the approach described above, the average molecular mass for this compound is therefore:\r\n<img class=\" alignnone\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211114\/CNX_Chem_03_01_ibuprofenmass_img1.jpg\" alt=\"A table is shown that is made up of six columns and five rows. The header row reads: \u201cElement,\u201d \u201cQuantity,\u201d a blank space, \u201cAverage atomic mass (a m u),\u201d a blank space, and \u201cSubtotal (a m u).\u201d The first column contains the symbols \u201cC,\u201d \u201cH,\u201d \u201cO,\u201d and a merged cell. The merged cell runs the length of the first five columns. The second column contains the numbers \u201c13,\u201d \u201c8,\u201d and \u201c2\u201d as well as the merged cell. The third column contains the multiplication symbol in each cell except for the last, merged cell. The fourth column contains the numbers \u201c12.01,\u201d \u201c1.008,\u201d and \u201c16.00\u201d as well as the merged cell. The fifth column contains the symbol \u201c=\u201d in each cell except for the last, merged cell. The sixth column contains the values \u201c156.13,\u201d \u201c18.114,\u201d \u201c32.00,\u201d and \u201c206.27.\u201d There is a thick black line below the number 32.00. The merged cell under the first five columns reads \u201cMolecular mass.\u201d To the right is a ball-and-stick model of the structure. At the center, it shows six black spheres arranged in a six-sided ring with alternating double bonds. The two black spheres at the top and bottom of the six-sided ring are each bonded to one, smaller, white sphere. The black sphere on the left side of the six-sided ring is connect to another black sphere. This sphere is connected to two smaller, white spheres and another black sphere. This black sphere is connected to one, smaller white sphere, and two other black spheres. Each of these last two black spheres is connected to two smaller, white spheres. The black sphere on the right side of the six-sided ring is connected to another black sphere. This black sphere is connected to one smaller, white sphere and two other black spheres. The black sphere that is connected to it and is situated to the top right is connected to two smaller, white spheres. The black sphere connected towards the bottom right is connected to two red spheres. It forms a double bond with one of these red spheres and the other red sphere is connected to a smaller, white sphere.\" width=\"876\" height=\"233\" \/>\r\n\r\n[\/hidden-answer]\r\n<h4><strong>Check Your Learning<\/strong><\/h4>\r\nAcetaminophen, C<sub>8<\/sub>H<sub>9<\/sub>NO<sub>2<\/sub>, is a covalent compound and the active ingredient in several popular nonprescription pain medications, such as Tylenol. What is the molecular mass (amu) for this compound?\r\n\r\n[reveal-answer q=\"409467\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"409467\"]151.16 amu[\/hidden-answer]\r\n\r\n<\/div>\r\n<h3>Formula Mass for Ionic Compounds<\/h3>\r\nIonic compounds are composed of discrete cations and anions combined in ratios to yield electrically neutral bulk matter. The formula mass for an ionic compound is calculated in the same way as the formula mass for covalent compounds: by summing the average atomic masses of all the atoms in the compound\u2019s formula. Keep in mind, however, that the formula for an ionic compound does not represent the composition of a discrete molecule, so it may not correctly be referred to as the \u201cmolecular mass.\u201d\r\n\r\nAs an example, consider sodium chloride, NaCl, the chemical name for common table salt. Sodium chloride is an ionic compound composed of sodium cations, Na<sup>+<\/sup>, and chloride anions, Cl<sup>-<\/sup>, combined in a 1:1 ratio. The formula mass for this compound is computed as 58.44 amu (see Figure 3).\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"883\"]<img class=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211116\/CNX_Chem_03_01_saltMass1.jpg\" alt=\"A table and diagram are shown. The table is made up of six columns and four rows. The header row reads: \u201cElement,\u201d \u201cQuantity,\u201d a blank space, \u201cAverage atomic mass (a m u),\u201d a blank space and \u201cSubtotal (a m u).\u201d The first column contains the symbols \u201cN a\u201d, \u201cC l,\u201d and a merged cell. The merged cell runs the length of the first five columns. The second column contains the numbers \u201c1\u201d and \u201c1\u201d as well as the merged cell. The third column contains the multiplication symbol in each cell except for the last, merged cell. The fourth column contains the numbers \u201c22.99\u201d and \u201c35.45\u201d as well as the merged cell. The fifth column contains the symbol \u201c=\u201d in each cell except for the last, merged cell. The sixth column contains the values \u201c22.99,\u201d \u201c35.45,\u201d and \u201c58.44.\u201d There is a thick black line below the number \u201c35.45.\u201d The merged cell under the first five columns reads \u201cFormula mass.\u201d To the left of the table is a diagram of a chemical structure. The diagram shows green and purple spheres placed in an alternating pattern, making up the corners of eight stacked cubes to form one larger cube. The green spheres are slightly smaller than the purple spheres.\" width=\"883\" height=\"178\" \/> Figure 3. Table salt, NaCl, contains an array of sodium and chloride ions combined in a 1:1 ratio. Its formula mass is 58.44 amu.[\/caption]\r\n\r\nNote that the average masses of neutral sodium and chlorine atoms were used in this computation, rather than the masses for sodium cations and chlorine anions. This approach is perfectly acceptable when computing the formula mass of an ionic compound. Even though a sodium cation has a slightly smaller mass than a sodium atom (since it is missing an electron), this difference will be offset by the fact that a chloride anion is slightly more massive than a chloride atom (due to the extra electron). Moreover, the mass of an electron is negligibly small with respect to the mass of a typical atom. Even when calculating the mass of an isolated ion, the missing or additional electrons can generally be ignored, since their contribution to the overall mass is negligible, reflected only in the non-significant digits that will be lost when the computed mass is properly rounded. The few exceptions to this guideline are very light ions derived from elements with precisely known atomic masses.\r\n<div class=\"textbox examples\">\r\n<h3>Example 2: <strong>Computing Formula Mass for an Ionic Compound<\/strong><\/h3>\r\nAluminum sulfate, Al<sub>2<\/sub>(SO<sub>4<\/sub>)<sub>3<\/sub>, is an ionic compound that is used in the manufacture of paper and in various water purification processes. What is the formula mass (amu) of this compound?\r\n\r\n[reveal-answer q=\"781611\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"781611\"]\r\n\r\nThe formula for this compound indicates it contains Al<sup>3+<\/sup> and SO<sub>4<\/sub><sup>2-<\/sup> ions combined in a 2:3 ratio. For purposes of computing a formula mass, it is helpful to rewrite the formula in the simpler format, Al<sub>2<\/sub>S<sub>3<\/sub>O<sub>12<\/sub>. Following the approach outlined above, the formula mass for this compound is calculated as follows:\r\n<img class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211118\/CNX_Chem_03_01_alsulfatemass_img1.jpg\" alt=\"A table is shown that is made up of six columns and five rows. The header row reads: \u201cElement,\u201d \u201cQuantity,\u201d a blank space, \u201cAverage atomic mass (a m u),\u201d a blank space, and \u201cSubtotal (a m u).\u201d The first column contains the symbols \u201cA l,\u201d \u201cS,\u201d \u201cO,\u201d and a merged cell. The merged cell runs the length of the first five columns. The second column contains the numbers \u201c2,\u201d \u201c3,\u201d and \u201c12\u201d as well as the merged cell. The third column contains the multiplication symbol in each cell except for the last, merged cell. The fourth column contains the numbers \u201c26.98,\u201d \u201c32.06,\u201d and \u201c16.00\u201d as well as the merged cell. The fifth column contains the symbol \u201c=\u201d in each cell except for the last, merged cell. The sixth column contains the values \u201c53.96,\u201d \u201c96.18,\u201d \u201c192.00,\u201d and \u201c342.14.\u201d There is a thick black line under the number 192.00. The merged cell under the first five columns reads \u201cMolecular mass.\u201d To the right of this table is a ball-and-stick structure. It shows yellow and grey sphere connected to red spheres in a complex pattern. The yellow and grey spheres are similar in size, but the red spheres appear to be smaller by comparison.\" width=\"880\" height=\"234\" \/>\r\n\r\n[\/hidden-answer]\r\n<h4><strong>Check Your Learning<\/strong><\/h4>\r\nCalcium phosphate, Ca<sub>3<\/sub>(PO<sub>4<\/sub>)<sub>2<\/sub>, is an ionic compound and a common anti-caking agent added to food products. What is the formula mass (amu) of calcium phosphate?\r\n\r\n[reveal-answer q=\"953796\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"953796\"]310.18 amu[\/hidden-answer]\r\n\r\n<\/div>\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Key Concepts and Summary<\/h3>\r\nThe formula mass of a substance is the sum of the average atomic masses of each atom represented in the chemical formula and is expressed in atomic mass units. The formula mass of a covalent compound is also called the molecular mass.\r\n\r\n<\/div>\r\n<div class=\"textbox exercises\">\r\n<h3>Exercises<\/h3>\r\n<ol>\r\n \t<li>What is the total mass (amu) of carbon in each of the following molecules?\r\n<ol style=\"list-style-type: lower-alpha\">\r\n \t<li>CH<sub>4 <\/sub><\/li>\r\n \t<li>CHCl<sub>3 <\/sub><\/li>\r\n \t<li>C<sub>12<\/sub>H<sub>10<\/sub>O<sub>6 <\/sub><\/li>\r\n \t<li>CH<sub>3<\/sub>CH<sub>2<\/sub>CH<sub>2<\/sub>CH<sub>2<\/sub>CH<sub>3<\/sub><\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>What is the total mass of hydrogen in each of the molecules?\r\n<ol style=\"list-style-type: lower-alpha\">\r\n \t<li>CH<sub>4 <\/sub><\/li>\r\n \t<li>CHCl<sub>3 <\/sub><\/li>\r\n \t<li>C<sub>12<\/sub>H<sub>10<\/sub>O<sub>6 <\/sub><\/li>\r\n \t<li>CH<sub>3<\/sub>CH<sub>2<\/sub>CH<sub>2<\/sub>CH<sub>2<\/sub>CH<sub>3<\/sub><\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Calculate the molecular or formula mass of each of the following:\r\n<ol style=\"list-style-type: lower-alpha\">\r\n \t<li>P<sub>4 <\/sub><\/li>\r\n \t<li>H<sub>2<\/sub>O<\/li>\r\n \t<li>Ca(NO<sub>3<\/sub>)<sub>2 <\/sub><\/li>\r\n \t<li>CH<sub>3<\/sub>CO<sub>2<\/sub>H (acetic acid)<\/li>\r\n \t<li>C<sub>12<\/sub>H<sub>22<\/sub>O<sub>11<\/sub> (sucrose, cane sugar).<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Determine the molecular mass of the following compounds:\r\n<ol style=\"list-style-type: lower-alpha\">\r\n \t<li><img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211143\/CNX_Chem_03_01_Ex01_05a_img1.jpg\" alt=\"A structure is shown. A C atom is bonded to two C l atoms and forms a double bond with one O atom.\" \/><\/li>\r\n \t<li><img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211144\/CNX_Chem_03_01_Ex01_05b_img1.jpg\" alt=\"A structure is shown. Two C atoms form a triple bond with each other. Each C atom also forms a single bond with on H atom.\" \/><\/li>\r\n \t<li><img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211145\/CNX_Chem_03_01_Ex01_05c_img1.jpg\" alt=\"A structure is shown. Two C atoms form double bonds with each other. Each C atom also forms a single bond with an H atom and a B r atom.\" \/><\/li>\r\n \t<li><img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211146\/CNX_Chem_03_01_Ex01_05d_img1.jpg\" alt=\"A structure is shown. An S atom forms double bonds with two O atoms. The S atom also forms a single bond with an O atom which forms a single bond with an H atom. The S atom also forms a single bond with another O atom which forms a single bond with another H atom.\" \/><\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Determine the molecular mass of the following compounds:\r\n<ol style=\"list-style-type: lower-alpha\">\r\n \t<li><img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211147\/CNX_Chem_03_01_Ex01_06a_img1.jpg\" alt=\"A structure is shown. Two C atoms form double bonds with each other. The C atom on the left forms a single bond with two H atoms each. The C atom on the right forms a single bond with an H atom and with a C H subscript 2 C H subscript 3 group.\" \/><\/li>\r\n \t<li><img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211148\/CNX_Chem_03_01_Ex01_06b_img1.jpg\" alt=\"A structure is shown. There is a C atom which forms single bonds with three H atoms each. This C atom is bonded to another C atom. This second C atom forms a triple bond with another C atom which forms a single bond with a fourth C atom. The fourth C atom forms single bonds with three H atoms each.\" \/><\/li>\r\n \t<li><img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211149\/CNX_Chem_03_01_Ex01_06c_img1.jpg\" alt=\"A structure is shown. An S i atom forms a single bond with a C l atom, a single bond with a C l atom, a single bond with an H atom, and a single bond with another S i atom. The second S i atom froms a single bond with a C l atom, a single bond with a C l atom, and a single bond with an H atom.\" \/><\/li>\r\n \t<li><img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211150\/CNX_Chem_03_01_Ex01_06d_img1.jpg\" alt=\"A structure is shown. A P atom forms a double bond with an O atom. It also forms a single bond with an O atom which forms a single bond with an H atom. It also forms a single bond with another O atom which forms a single bond with an H atom. It also forms a single bond with another O atom which forms a single bond with an H atom.\" \/><\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Which molecule has a molecular mass of 28.05 amu?\r\n<ol style=\"list-style-type: lower-alpha\">\r\n \t<li><img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211151\/CNX_Chem_03_01_Ex01_07a_img1.jpg\" alt=\"A structure is shown. A C atom forms a triple bond with another C atom. Each C atom also forms a single bond with an H atom.\" \/><\/li>\r\n \t<li><img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211152\/CNX_Chem_03_01_Ex01_07b_img1.jpg\" alt=\"A structure is shown. Two C atoms form a double bond with each other. Each C atom also forms a single bond with two H atoms.\" \/><\/li>\r\n \t<li><img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211153\/CNX_Chem_03_01_Ex01_07c_img1.jpg\" alt=\"A structure is shown. A C atom forms a single bond with three H atoms each and with another C atom. The second C atom also forms a single bond with three H atoms each.\" \/><\/li>\r\n<\/ol>\r\n[reveal-answer q=\"649796\"]Show Selected Answers[\/reveal-answer]\r\n[hidden-answer a=\"649796\"]\r\n\r\n1. Each molecule has the following mass (amu) of carbon.\r\n<ol style=\"list-style-type: lower-alpha\">\r\n \t<li>[latex]1\\times 12.01\\text{ amu}=12.01\\text{ amu}[\/latex]<\/li>\r\n \t<li>[latex]1\\times 12.01\\text{ amu}=12.01\\text{ amu}[\/latex]<\/li>\r\n \t<li>[latex]12\\times 12.01\\text{ amu}=144.12\\text{ amu}[\/latex]<\/li>\r\n \t<li>[latex]5\\times 12.01\\text{ amu}=60.05\\text{ amu}[\/latex]<\/li>\r\n<\/ol>\r\n3. The molecular or formula masses are as follows:\r\n<ol style=\"list-style-type: lower-alpha\">\r\n \t<li>[latex]4\\times 30.974\\text{ amu}=123.896\\text{ amu}[\/latex]<\/li>\r\n \t<li>[latex]2\\times 1.008\\text{ amu}+15.999\\text{ amu}=18.015\\text{ amu}[\/latex]<\/li>\r\n \t<li>[latex]40\\times 0.078\\text{ amu}+2\\times 14.007\\text{ amu}+6\\times 15.999\\text{ amu}=164.086\\text{ amu}[\/latex]<\/li>\r\n \t<li>[latex]2\\times 12.011\\text{ amu}+4\\times 1.008\\text{ amu}+2\\times 15.999\\text{ amu}=60.052\\text{ amu}[\/latex]<\/li>\r\n \t<li>[latex]12\\times 12.011\\text{ amu}+22\\times 1.008\\text{ amu}\\times 11\\times 15.999\\text{ amu}=342.297\\text{ amu}[\/latex]<\/li>\r\n<\/ol>\r\n5. The molecular mass of each compound is as follows:\r\n<ol style=\"list-style-type: lower-alpha\">\r\n \t<li>C<sub>4<\/sub>H<sub>8\r\n<\/sub>[latex]\\begin{array}{ll}4\\text{C}\\times 12.011\\hfill &amp; =48.044\\text{amu}\\hfill \\\\ 8\\text{H}\\times 1.0079\\hfill &amp; =\\underline{8.06352\\text{amu}}\\hfill \\\\ \\hfill &amp; =56.107\\text{amu}\\hfill \\end{array}[\/latex]<\/li>\r\n \t<li>C<sub>4<\/sub>H<sub>6\r\n<\/sub><span style=\"line-height: 1.5\">[latex]\\begin{array}{ll}4\\text{C}\\times 12.011\\hfill &amp; =48.044\\text{amu}\\hfill \\\\ 6\\text{H}\\times 1.0079\\hfill &amp; =\\underline{6.0474\\text{amu}}\\hfill \\\\ \\hfill &amp; =54.091\\text{amu}\\hfill \\end{array}[\/latex]<\/span><\/li>\r\n \t<li>H<sub>2<\/sub>Si<sub>2<\/sub>Cl<sub>4\r\n<\/sub><span style=\"line-height: 1.5\">[latex]\\begin{array}{ll}\\hfill 2\\text{H}\\times 1.0079&amp; =2.01558\\text{amu}\\hfill \\\\ 2\\text{Si}\\times 28.0855\\hfill &amp; =56.1710\\text{amu}\\hfill \\\\ 4\\text{Cl}\\times 35.4527\\hfill &amp; =\\underline{141.8108\\text{amu}}\\hfill \\\\ \\hfill &amp; =199.9976\\text{amu}\\hfill \\end{array}[\/latex]<\/span><\/li>\r\n \t<li>H<sub>3<\/sub>PO<sub>4\r\n<\/sub><span style=\"line-height: 1.5\">[latex]\\begin{array}{ll}\\hfill 3\\text{H}\\times 1.0079&amp; =3.0237\\text{amu}\\hfill \\\\ 1\\text{P}\\times 30.973762\\hfill &amp; =30.973762\\text{amu}\\hfill \\\\ \\hfill 4\\text{O}\\times 15.9994&amp; =\\underline{63.9976\\text{amu}}\\hfill \\\\ \\hfill &amp; =97.9950\\text{amu}\\hfill \\end{array}[\/latex]<\/span><\/li>\r\n<\/ol>\r\n[\/hidden-answer]<\/li>\r\n<\/ol>\r\n<\/div>\r\n<h2>Glossary<\/h2>\r\n<strong>formula mass:\u00a0<\/strong>sum of the average masses for all atoms represented in a chemical formula; for covalent compounds, this is also the molecular mass\r\n\r\n<strong>molar mass:\u00a0<\/strong>mass in grams of 1 mole of a substance","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Objectives<\/h3>\n<p>By the end of this section, you will be able to:<\/p>\n<ul>\n<li>Calculate formula masses for covalent and ionic compounds<\/li>\n<\/ul>\n<\/div>\n<p>We can argue that modern chemical science began when scientists started exploring the quantitative as well as the qualitative aspects of chemistry. For example, Dalton\u2019s atomic theory was an attempt to explain the results of measurements that allowed him to calculate the relative masses of elements combined in various compounds. Understanding the relationship between the masses of atoms and the chemical formulas of compounds allows us to quantitatively describe the composition of substances.<\/p>\n<h2>Formula Mass<\/h2>\n<p>In an earlier chapter, we described the development of the atomic mass unit, the concept of average atomic masses, and the use of chemical formulas to represent the elemental makeup of substances. These ideas can be extended to calculate the <strong>formula mass <\/strong>of a substance by summing the average atomic masses of all the atoms represented in the substance\u2019s formula.<\/p>\n<h3>Formula Mass for Covalent Substances<\/h3>\n<p>For covalent substances, the formula represents the numbers and types of atoms composing a single molecule of the substance; therefore, the formula mass may be correctly referred to as a molecular mass. Consider chloroform (CHCl<sub>3<\/sub>), a covalent compound once used as a surgical anesthetic and now primarily used in the production of the \u201canti-stick\u201d polymer, Teflon. The molecular formula of chloroform indicates that a single molecule contains one carbon atom, one hydrogen atom, and three chlorine atoms. The average molecular mass of a chloroform molecule is therefore equal to the sum of the average atomic masses of these atoms. Figure 1 outlines the calculations used to derive the molecular mass of chloroform, which is 119.37 amu.<\/p>\n<div style=\"width: 890px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211111\/CNX_Chem_03_01_chloroform1.jpg\" alt=\"A table and diagram are shown. The table is made up of six columns and five rows. The header row reads: \u201cElement,\u201d \u201cQuantity,\u201d a blank space, \u201cAverage atomic mass (a m u),\u201d a blank space, and \u201cSubtotal (a m u).\u201d The first column contains the symbols \u201cC,\u201d \u201cH,\u201d \u201cC l\u201d and a blank, merged cell that runs the width of the first five columns. The second column contains the numbers \u201c1,\u201d \u201c1,\u201d and \u201c3\u201d as well as the merged cell. The third column contains the multiplication symbol in each cell except for the last, merged cell. The fourth column contains the numbers \u201c12.01,\u201d \u201c1.008,\u201d and \u201c35.45\u201d as well as the merged cell. The fifth column contains the symbol \u201c=\u201d in each cell except for the last, merged cell. The sixth column contains the values \u201c12.01,\u201d \u201c1.008,\u201d \u201c106.35,\u201d and \u201c119.37.\u201d There is a thick black line below the number 106.35. The merged cell under the first five columns reads \u201cMolecular mass.\u201d To the left of the table is a diagram of a molecule. Three green spheres are attached to a slightly smaller black sphere, which is also attached to a smaller white sphere. The green spheres lie beneath and to the sides of the black sphere while the white sphere is located straight up from the black sphere.\" width=\"880\" height=\"216\" \/><\/p>\n<p class=\"wp-caption-text\">Figure 1. The average mass of a chloroform molecule, CHCl<sub>3<\/sub>, is 119.37 amu, which is the sum of the average atomic masses of each of its constituent atoms. The model shows the molecular structure of chloroform.<\/p>\n<\/div>\n<p>Likewise, the molecular mass of an aspirin molecule, C<sub>9<\/sub>H<sub>8<\/sub>O<sub>4<\/sub>, is the sum of the atomic masses of nine carbon atoms, eight hydrogen atoms, and four oxygen atoms, which amounts to 180.15 amu (Figure 2).<\/p>\n<div style=\"width: 890px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211113\/CNX_Chem_03_01_aspirin1.jpg\" alt=\"A table and diagram are shown. The table is made up of six columns and five rows. The header row reads: \u201cElement,\u201d \u201cQuantity,\u201d a blank space, \u201cAverage atomic mass (a m u),\u201d a blank space, and \u201cSubtotal (a m u).\u201d The first column contains the symbols \u201cC,\u201d \u201cH,\u201d \u201cO,\u201d and a merged cell. The merged cell runs the length of the first five columns. The second column contains the numbers \u201c9,\u201d \u201c8,\u201d and \u201c4\u201d as well as the merged, cell. The third column contains the multiplication symbol in each cell except for the last, merged cell. The fourth column contains the numbers \u201c12.01,\u201d \u201c1.008,\u201d and \u201c16.00\u201d as well as the merged cell. The fifth column contains the symbol \u201c=\u201d in each cell except for the last, merged cell. The sixth column contains the values: \u201c108.09,\u201d \u201c8.064,\u201d \u201c64.00,\u201d and \u201c180.15.\u201d There is a thick black line below the number 64.00. The merged cell under the first five columns reads \u201cMolecular mass.\u201d To the left of the table is a diagram of a molecule. Six black spheres are located in a six-sided ring and connected by alternating double and single black bonds. Attached to each of the four black spheres is one smaller white sphere. Attached to the farthest right black sphere is a red sphere, connected to two more black spheres, all in a row. Attached to the last black sphere of that row are two more white spheres. Attached to the first black sphere of that row is another red sphere. A black sphere, attached to two red spheres and a white sphere is attached to the black sphere on the top right of the six-sided ring.\" width=\"880\" height=\"216\" \/><\/p>\n<p class=\"wp-caption-text\">Figure 2. The average mass of an aspirin molecule is 180.15 amu. The model shows the molecular structure of aspirin, C<sub>9<\/sub>H<sub>8<\/sub>O<sub>4<\/sub>.<\/p>\n<\/div>\n<div class=\"textbox examples\">\n<h3>Example 1: <strong>Computing Molecular Mass for a Covalent Compound<\/strong><\/h3>\n<p>Ibuprofen, C<sub>13<\/sub>H<sub>18<\/sub>O<sub>2<\/sub>, is a covalent compound and the active ingredient in several popular nonprescription pain medications, such as Advil and Motrin. What is the molecular mass (amu) for this compound?<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q557459\">Show Answer<\/span><\/p>\n<div id=\"q557459\" class=\"hidden-answer\" style=\"display: none\">\n<p>Molecules of this compound are comprised of 13 carbon atoms, 18 hydrogen atoms, and 2 oxygen atoms. Following the approach described above, the average molecular mass for this compound is therefore:<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"alignnone\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211114\/CNX_Chem_03_01_ibuprofenmass_img1.jpg\" alt=\"A table is shown that is made up of six columns and five rows. The header row reads: \u201cElement,\u201d \u201cQuantity,\u201d a blank space, \u201cAverage atomic mass (a m u),\u201d a blank space, and \u201cSubtotal (a m u).\u201d The first column contains the symbols \u201cC,\u201d \u201cH,\u201d \u201cO,\u201d and a merged cell. The merged cell runs the length of the first five columns. The second column contains the numbers \u201c13,\u201d \u201c8,\u201d and \u201c2\u201d as well as the merged cell. The third column contains the multiplication symbol in each cell except for the last, merged cell. The fourth column contains the numbers \u201c12.01,\u201d \u201c1.008,\u201d and \u201c16.00\u201d as well as the merged cell. The fifth column contains the symbol \u201c=\u201d in each cell except for the last, merged cell. The sixth column contains the values \u201c156.13,\u201d \u201c18.114,\u201d \u201c32.00,\u201d and \u201c206.27.\u201d There is a thick black line below the number 32.00. The merged cell under the first five columns reads \u201cMolecular mass.\u201d To the right is a ball-and-stick model of the structure. At the center, it shows six black spheres arranged in a six-sided ring with alternating double bonds. The two black spheres at the top and bottom of the six-sided ring are each bonded to one, smaller, white sphere. The black sphere on the left side of the six-sided ring is connect to another black sphere. This sphere is connected to two smaller, white spheres and another black sphere. This black sphere is connected to one, smaller white sphere, and two other black spheres. Each of these last two black spheres is connected to two smaller, white spheres. The black sphere on the right side of the six-sided ring is connected to another black sphere. This black sphere is connected to one smaller, white sphere and two other black spheres. The black sphere that is connected to it and is situated to the top right is connected to two smaller, white spheres. The black sphere connected towards the bottom right is connected to two red spheres. It forms a double bond with one of these red spheres and the other red sphere is connected to a smaller, white sphere.\" width=\"876\" height=\"233\" \/><\/p>\n<\/div>\n<\/div>\n<h4><strong>Check Your Learning<\/strong><\/h4>\n<p>Acetaminophen, C<sub>8<\/sub>H<sub>9<\/sub>NO<sub>2<\/sub>, is a covalent compound and the active ingredient in several popular nonprescription pain medications, such as Tylenol. What is the molecular mass (amu) for this compound?<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q409467\">Show Answer<\/span><\/p>\n<div id=\"q409467\" class=\"hidden-answer\" style=\"display: none\">151.16 amu<\/div>\n<\/div>\n<\/div>\n<h3>Formula Mass for Ionic Compounds<\/h3>\n<p>Ionic compounds are composed of discrete cations and anions combined in ratios to yield electrically neutral bulk matter. The formula mass for an ionic compound is calculated in the same way as the formula mass for covalent compounds: by summing the average atomic masses of all the atoms in the compound\u2019s formula. Keep in mind, however, that the formula for an ionic compound does not represent the composition of a discrete molecule, so it may not correctly be referred to as the \u201cmolecular mass.\u201d<\/p>\n<p>As an example, consider sodium chloride, NaCl, the chemical name for common table salt. Sodium chloride is an ionic compound composed of sodium cations, Na<sup>+<\/sup>, and chloride anions, Cl<sup>&#8211;<\/sup>, combined in a 1:1 ratio. The formula mass for this compound is computed as 58.44 amu (see Figure 3).<\/p>\n<div style=\"width: 893px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211116\/CNX_Chem_03_01_saltMass1.jpg\" alt=\"A table and diagram are shown. The table is made up of six columns and four rows. The header row reads: \u201cElement,\u201d \u201cQuantity,\u201d a blank space, \u201cAverage atomic mass (a m u),\u201d a blank space and \u201cSubtotal (a m u).\u201d The first column contains the symbols \u201cN a\u201d, \u201cC l,\u201d and a merged cell. The merged cell runs the length of the first five columns. The second column contains the numbers \u201c1\u201d and \u201c1\u201d as well as the merged cell. The third column contains the multiplication symbol in each cell except for the last, merged cell. The fourth column contains the numbers \u201c22.99\u201d and \u201c35.45\u201d as well as the merged cell. The fifth column contains the symbol \u201c=\u201d in each cell except for the last, merged cell. The sixth column contains the values \u201c22.99,\u201d \u201c35.45,\u201d and \u201c58.44.\u201d There is a thick black line below the number \u201c35.45.\u201d The merged cell under the first five columns reads \u201cFormula mass.\u201d To the left of the table is a diagram of a chemical structure. The diagram shows green and purple spheres placed in an alternating pattern, making up the corners of eight stacked cubes to form one larger cube. The green spheres are slightly smaller than the purple spheres.\" width=\"883\" height=\"178\" \/><\/p>\n<p class=\"wp-caption-text\">Figure 3. Table salt, NaCl, contains an array of sodium and chloride ions combined in a 1:1 ratio. Its formula mass is 58.44 amu.<\/p>\n<\/div>\n<p>Note that the average masses of neutral sodium and chlorine atoms were used in this computation, rather than the masses for sodium cations and chlorine anions. This approach is perfectly acceptable when computing the formula mass of an ionic compound. Even though a sodium cation has a slightly smaller mass than a sodium atom (since it is missing an electron), this difference will be offset by the fact that a chloride anion is slightly more massive than a chloride atom (due to the extra electron). Moreover, the mass of an electron is negligibly small with respect to the mass of a typical atom. Even when calculating the mass of an isolated ion, the missing or additional electrons can generally be ignored, since their contribution to the overall mass is negligible, reflected only in the non-significant digits that will be lost when the computed mass is properly rounded. The few exceptions to this guideline are very light ions derived from elements with precisely known atomic masses.<\/p>\n<div class=\"textbox examples\">\n<h3>Example 2: <strong>Computing Formula Mass for an Ionic Compound<\/strong><\/h3>\n<p>Aluminum sulfate, Al<sub>2<\/sub>(SO<sub>4<\/sub>)<sub>3<\/sub>, is an ionic compound that is used in the manufacture of paper and in various water purification processes. What is the formula mass (amu) of this compound?<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q781611\">Show Answer<\/span><\/p>\n<div id=\"q781611\" class=\"hidden-answer\" style=\"display: none\">\n<p>The formula for this compound indicates it contains Al<sup>3+<\/sup> and SO<sub>4<\/sub><sup>2-<\/sup> ions combined in a 2:3 ratio. For purposes of computing a formula mass, it is helpful to rewrite the formula in the simpler format, Al<sub>2<\/sub>S<sub>3<\/sub>O<sub>12<\/sub>. Following the approach outlined above, the formula mass for this compound is calculated as follows:<br \/>\n<img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211118\/CNX_Chem_03_01_alsulfatemass_img1.jpg\" alt=\"A table is shown that is made up of six columns and five rows. The header row reads: \u201cElement,\u201d \u201cQuantity,\u201d a blank space, \u201cAverage atomic mass (a m u),\u201d a blank space, and \u201cSubtotal (a m u).\u201d The first column contains the symbols \u201cA l,\u201d \u201cS,\u201d \u201cO,\u201d and a merged cell. The merged cell runs the length of the first five columns. The second column contains the numbers \u201c2,\u201d \u201c3,\u201d and \u201c12\u201d as well as the merged cell. The third column contains the multiplication symbol in each cell except for the last, merged cell. The fourth column contains the numbers \u201c26.98,\u201d \u201c32.06,\u201d and \u201c16.00\u201d as well as the merged cell. The fifth column contains the symbol \u201c=\u201d in each cell except for the last, merged cell. The sixth column contains the values \u201c53.96,\u201d \u201c96.18,\u201d \u201c192.00,\u201d and \u201c342.14.\u201d There is a thick black line under the number 192.00. The merged cell under the first five columns reads \u201cMolecular mass.\u201d To the right of this table is a ball-and-stick structure. It shows yellow and grey sphere connected to red spheres in a complex pattern. The yellow and grey spheres are similar in size, but the red spheres appear to be smaller by comparison.\" width=\"880\" height=\"234\" \/><\/p>\n<\/div>\n<\/div>\n<h4><strong>Check Your Learning<\/strong><\/h4>\n<p>Calcium phosphate, Ca<sub>3<\/sub>(PO<sub>4<\/sub>)<sub>2<\/sub>, is an ionic compound and a common anti-caking agent added to food products. What is the formula mass (amu) of calcium phosphate?<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q953796\">Show Answer<\/span><\/p>\n<div id=\"q953796\" class=\"hidden-answer\" style=\"display: none\">310.18 amu<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox key-takeaways\">\n<h3>Key Concepts and Summary<\/h3>\n<p>The formula mass of a substance is the sum of the average atomic masses of each atom represented in the chemical formula and is expressed in atomic mass units. The formula mass of a covalent compound is also called the molecular mass.<\/p>\n<\/div>\n<div class=\"textbox exercises\">\n<h3>Exercises<\/h3>\n<ol>\n<li>What is the total mass (amu) of carbon in each of the following molecules?\n<ol style=\"list-style-type: lower-alpha\">\n<li>CH<sub>4 <\/sub><\/li>\n<li>CHCl<sub>3 <\/sub><\/li>\n<li>C<sub>12<\/sub>H<sub>10<\/sub>O<sub>6 <\/sub><\/li>\n<li>CH<sub>3<\/sub>CH<sub>2<\/sub>CH<sub>2<\/sub>CH<sub>2<\/sub>CH<sub>3<\/sub><\/li>\n<\/ol>\n<\/li>\n<li>What is the total mass of hydrogen in each of the molecules?\n<ol style=\"list-style-type: lower-alpha\">\n<li>CH<sub>4 <\/sub><\/li>\n<li>CHCl<sub>3 <\/sub><\/li>\n<li>C<sub>12<\/sub>H<sub>10<\/sub>O<sub>6 <\/sub><\/li>\n<li>CH<sub>3<\/sub>CH<sub>2<\/sub>CH<sub>2<\/sub>CH<sub>2<\/sub>CH<sub>3<\/sub><\/li>\n<\/ol>\n<\/li>\n<li>Calculate the molecular or formula mass of each of the following:\n<ol style=\"list-style-type: lower-alpha\">\n<li>P<sub>4 <\/sub><\/li>\n<li>H<sub>2<\/sub>O<\/li>\n<li>Ca(NO<sub>3<\/sub>)<sub>2 <\/sub><\/li>\n<li>CH<sub>3<\/sub>CO<sub>2<\/sub>H (acetic acid)<\/li>\n<li>C<sub>12<\/sub>H<sub>22<\/sub>O<sub>11<\/sub> (sucrose, cane sugar).<\/li>\n<\/ol>\n<\/li>\n<li>Determine the molecular mass of the following compounds:\n<ol style=\"list-style-type: lower-alpha\">\n<li><img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211143\/CNX_Chem_03_01_Ex01_05a_img1.jpg\" alt=\"A structure is shown. A C atom is bonded to two C l atoms and forms a double bond with one O atom.\" \/><\/li>\n<li><img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211144\/CNX_Chem_03_01_Ex01_05b_img1.jpg\" alt=\"A structure is shown. Two C atoms form a triple bond with each other. Each C atom also forms a single bond with on H atom.\" \/><\/li>\n<li><img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211145\/CNX_Chem_03_01_Ex01_05c_img1.jpg\" alt=\"A structure is shown. Two C atoms form double bonds with each other. Each C atom also forms a single bond with an H atom and a B r atom.\" \/><\/li>\n<li><img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211146\/CNX_Chem_03_01_Ex01_05d_img1.jpg\" alt=\"A structure is shown. An S atom forms double bonds with two O atoms. The S atom also forms a single bond with an O atom which forms a single bond with an H atom. The S atom also forms a single bond with another O atom which forms a single bond with another H atom.\" \/><\/li>\n<\/ol>\n<\/li>\n<li>Determine the molecular mass of the following compounds:\n<ol style=\"list-style-type: lower-alpha\">\n<li><img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211147\/CNX_Chem_03_01_Ex01_06a_img1.jpg\" alt=\"A structure is shown. Two C atoms form double bonds with each other. The C atom on the left forms a single bond with two H atoms each. The C atom on the right forms a single bond with an H atom and with a C H subscript 2 C H subscript 3 group.\" \/><\/li>\n<li><img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211148\/CNX_Chem_03_01_Ex01_06b_img1.jpg\" alt=\"A structure is shown. There is a C atom which forms single bonds with three H atoms each. This C atom is bonded to another C atom. This second C atom forms a triple bond with another C atom which forms a single bond with a fourth C atom. The fourth C atom forms single bonds with three H atoms each.\" \/><\/li>\n<li><img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211149\/CNX_Chem_03_01_Ex01_06c_img1.jpg\" alt=\"A structure is shown. An S i atom forms a single bond with a C l atom, a single bond with a C l atom, a single bond with an H atom, and a single bond with another S i atom. The second S i atom froms a single bond with a C l atom, a single bond with a C l atom, and a single bond with an H atom.\" \/><\/li>\n<li><img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211150\/CNX_Chem_03_01_Ex01_06d_img1.jpg\" alt=\"A structure is shown. A P atom forms a double bond with an O atom. It also forms a single bond with an O atom which forms a single bond with an H atom. It also forms a single bond with another O atom which forms a single bond with an H atom. It also forms a single bond with another O atom which forms a single bond with an H atom.\" \/><\/li>\n<\/ol>\n<\/li>\n<li>Which molecule has a molecular mass of 28.05 amu?\n<ol style=\"list-style-type: lower-alpha\">\n<li><img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211151\/CNX_Chem_03_01_Ex01_07a_img1.jpg\" alt=\"A structure is shown. A C atom forms a triple bond with another C atom. Each C atom also forms a single bond with an H atom.\" \/><\/li>\n<li><img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211152\/CNX_Chem_03_01_Ex01_07b_img1.jpg\" alt=\"A structure is shown. Two C atoms form a double bond with each other. Each C atom also forms a single bond with two H atoms.\" \/><\/li>\n<li><img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/887\/2015\/04\/23211153\/CNX_Chem_03_01_Ex01_07c_img1.jpg\" alt=\"A structure is shown. A C atom forms a single bond with three H atoms each and with another C atom. The second C atom also forms a single bond with three H atoms each.\" \/><\/li>\n<\/ol>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q649796\">Show Selected Answers<\/span><\/p>\n<div id=\"q649796\" class=\"hidden-answer\" style=\"display: none\">\n<p>1. Each molecule has the following mass (amu) of carbon.<\/p>\n<ol style=\"list-style-type: lower-alpha\">\n<li>[latex]1\\times 12.01\\text{ amu}=12.01\\text{ amu}[\/latex]<\/li>\n<li>[latex]1\\times 12.01\\text{ amu}=12.01\\text{ amu}[\/latex]<\/li>\n<li>[latex]12\\times 12.01\\text{ amu}=144.12\\text{ amu}[\/latex]<\/li>\n<li>[latex]5\\times 12.01\\text{ amu}=60.05\\text{ amu}[\/latex]<\/li>\n<\/ol>\n<p>3. The molecular or formula masses are as follows:<\/p>\n<ol style=\"list-style-type: lower-alpha\">\n<li>[latex]4\\times 30.974\\text{ amu}=123.896\\text{ amu}[\/latex]<\/li>\n<li>[latex]2\\times 1.008\\text{ amu}+15.999\\text{ amu}=18.015\\text{ amu}[\/latex]<\/li>\n<li>[latex]40\\times 0.078\\text{ amu}+2\\times 14.007\\text{ amu}+6\\times 15.999\\text{ amu}=164.086\\text{ amu}[\/latex]<\/li>\n<li>[latex]2\\times 12.011\\text{ amu}+4\\times 1.008\\text{ amu}+2\\times 15.999\\text{ amu}=60.052\\text{ amu}[\/latex]<\/li>\n<li>[latex]12\\times 12.011\\text{ amu}+22\\times 1.008\\text{ amu}\\times 11\\times 15.999\\text{ amu}=342.297\\text{ amu}[\/latex]<\/li>\n<\/ol>\n<p>5. The molecular mass of each compound is as follows:<\/p>\n<ol style=\"list-style-type: lower-alpha\">\n<li>C<sub>4<\/sub>H<sub>8<br \/>\n<\/sub>[latex]\\begin{array}{ll}4\\text{C}\\times 12.011\\hfill & =48.044\\text{amu}\\hfill \\\\ 8\\text{H}\\times 1.0079\\hfill & =\\underline{8.06352\\text{amu}}\\hfill \\\\ \\hfill & =56.107\\text{amu}\\hfill \\end{array}[\/latex]<\/li>\n<li>C<sub>4<\/sub>H<sub>6<br \/>\n<\/sub><span style=\"line-height: 1.5\">[latex]\\begin{array}{ll}4\\text{C}\\times 12.011\\hfill & =48.044\\text{amu}\\hfill \\\\ 6\\text{H}\\times 1.0079\\hfill & =\\underline{6.0474\\text{amu}}\\hfill \\\\ \\hfill & =54.091\\text{amu}\\hfill \\end{array}[\/latex]<\/span><\/li>\n<li>H<sub>2<\/sub>Si<sub>2<\/sub>Cl<sub>4<br \/>\n<\/sub><span style=\"line-height: 1.5\">[latex]\\begin{array}{ll}\\hfill 2\\text{H}\\times 1.0079& =2.01558\\text{amu}\\hfill \\\\ 2\\text{Si}\\times 28.0855\\hfill & =56.1710\\text{amu}\\hfill \\\\ 4\\text{Cl}\\times 35.4527\\hfill & =\\underline{141.8108\\text{amu}}\\hfill \\\\ \\hfill & =199.9976\\text{amu}\\hfill \\end{array}[\/latex]<\/span><\/li>\n<li>H<sub>3<\/sub>PO<sub>4<br \/>\n<\/sub><span style=\"line-height: 1.5\">[latex]\\begin{array}{ll}\\hfill 3\\text{H}\\times 1.0079& =3.0237\\text{amu}\\hfill \\\\ 1\\text{P}\\times 30.973762\\hfill & =30.973762\\text{amu}\\hfill \\\\ \\hfill 4\\text{O}\\times 15.9994& =\\underline{63.9976\\text{amu}}\\hfill \\\\ \\hfill & =97.9950\\text{amu}\\hfill \\end{array}[\/latex]<\/span><\/li>\n<\/ol>\n<\/div>\n<\/div>\n<\/li>\n<\/ol>\n<\/div>\n<h2>Glossary<\/h2>\n<p><strong>formula mass:\u00a0<\/strong>sum of the average masses for all atoms represented in a chemical formula; for covalent compounds, this is also the molecular mass<\/p>\n<p><strong>molar mass:\u00a0<\/strong>mass in grams of 1 mole of a substance<\/p>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-1382\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>chemistry. <strong>Provided by<\/strong>: OpenStax College. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: Download for free at https:\/\/openstaxcollege.org\/textbooks\/chemistry\/get<\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":6181,"menu_order":3,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"chemistry\",\"author\":\"\",\"organization\":\"OpenStax College\",\"url\":\"\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"Download for free at https:\/\/openstaxcollege.org\/textbooks\/chemistry\/get\"}]","CANDELA_OUTCOMES_GUID":"","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-1382","chapter","type-chapter","status-publish","hentry"],"part":1128,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-introductorychemistry\/wp-json\/pressbooks\/v2\/chapters\/1382","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-introductorychemistry\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-introductorychemistry\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-introductorychemistry\/wp-json\/wp\/v2\/users\/6181"}],"version-history":[{"count":5,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-introductorychemistry\/wp-json\/pressbooks\/v2\/chapters\/1382\/revisions"}],"predecessor-version":[{"id":1388,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-introductorychemistry\/wp-json\/pressbooks\/v2\/chapters\/1382\/revisions\/1388"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-introductorychemistry\/wp-json\/pressbooks\/v2\/parts\/1128"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-introductorychemistry\/wp-json\/pressbooks\/v2\/chapters\/1382\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-introductorychemistry\/wp-json\/wp\/v2\/media?parent=1382"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-introductorychemistry\/wp-json\/pressbooks\/v2\/chapter-type?post=1382"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-introductorychemistry\/wp-json\/wp\/v2\/contributor?post=1382"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-introductorychemistry\/wp-json\/wp\/v2\/license?post=1382"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}