Check Your Knowledge: Self-Test

  1. Determine the molarity for each of the following solutions:
    1. 0.444 mol of CoCl2 in 0.654 L of solution
    2. 98.0 g of phosphoric acid, H3PO4, in 1.00 L of solution
    3. 0.2074 g of calcium hydroxide, Ca(OH)2, in 40.00 mL of solution
    4. 10.5 kg of Na2SO4•10H2O in 18.60 L of solution
    5. [latex]7.0\times {10}^{-3}\text{mol}[/latex] of I2 in 100.0 mL of solution
    6. [latex]1.8\times {10}^{4}\text{mg}[/latex] of HCl in 0.075 L of solution
  2. What is the molarity of the diluted solution when each of the following solutions is diluted to the given final volume?
    1. 1.00 L of a 0.250-M solution of Fe(NO3)3 is diluted to a final volume of 2.00 L
    2. 0.5000 L of a 0.1222-M solution of C3H7OH is diluted to a final volume of 1.250 L
    3. 2.35 L of a 0.350-M solution of H3PO4 is diluted to a final volume of 4.00 L
    4. 22.50 mL of a 0.025-M solution of C12H22O11 is diluted to 100.0 mL
  3. What is the final concentration of the solution produced when 225.5 mL of a 0.09988-M solution of Na2CO3 is allowed to evaporate until the solution volume is reduced to 45.00 mL?
  4. A throat spray is 1.40% by mass phenol, C6H5OH, in water. If the solution has a density of 0.9956 g/mL, calculate the molarity of the solution.
  5. Copper(I) iodide (CuI) is often added to table salt as a dietary source of iodine. How many moles of CuI are contained in 1.00 lb (454 g) of table salt containing 0.0100% CuI by mass?
  6. Explain why the ions Na+ and Cl− are strongly solvated in water but not in hexane, a solvent composed of nonpolar molecules.

  7. Which of the following statements is not true?

  • a. Water is polar.
  • b. Water stabilizes temperature.
  • c. Water is essential for life.
  • d. Water is the most abundant molecule in the Earth’s atmosphere.

7.

8. When acids are added to a solution, the pH should ________.

  1. decrease
  2. increase
  3. stay the same
  4. cannot tell without testing

9. A molecule that binds up excess hydrogen ions in a solution is called a(n) ________.

  1. acid
  2. isotope
  3. base
  4. donator

10. Which of the following statements is true?

  1. Acids and bases cannot mix together.
  2. Acids and bases will neutralize each other.
  3. Acids, but not bases, can change the pH of a solution.
  4. Acids donate hydroxide ions (OH–); bases donate hydrogen ions (H+).

11. Discuss how buffers help prevent drastic swings in pH.

12. Why can some insects walk on water?