Additional Exercises
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Write the balanced chemical equation between Zn metal and HCl(aq). The other product is ZnCl2.
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Write the neutralization reaction in which ZnCl2, also found in Exercise 1, is the salt product.
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Why isn’t an oxide compound like CaO considered a salt? (Hint: what acid-base combination would be needed to make it if it were a salt?)
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Metal oxides are considered basic because they react with H2O to form OH compounds. Write the chemical equation for a reaction that forms a base when CaO is combined with H2O.
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Write the balanced chemical equation between aluminum hydroxide and sulfuric acid.
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Write the balanced chemical equation between phosphoric acid and barium hydroxide.
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Write the equation for the chemical reaction that occurs when caffeine (C8H10N4O2) acts as a Brønsted-Lowry base.
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Citric acid (C6H8O7) is the acid found in citrus fruits. It can lose a maximum of three H+ ions in the presence of a base. Write the chemical equations for citric acid acting stepwise as a Brønsted-Lowry acid.
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Can an amphiprotic substance be a strong acid and a strong base at the same time? Explain your answer.
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Can an amphiprotic substance be a weak acid and a weak base at the same time? If so, explain why and give an example.
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Under what conditions will the equivalence point of a titration be slightly acidic?
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Under what conditions will the equivalence point of a titration be slightly basic?
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Write the chemical equation for the autoionization of NH3.
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Write the chemical equation for the autoionization of HF.
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What is the pOH range for an acidic solution?
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What is the pOH range for a basic solution?
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The concentration of commercial HCl is about 12 M. What is its pH and pOH?
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The concentration of concentrated H2SO4 is about 18 M. Assuming only one H+ comes off the H2SO4 molecule, what is its pH and pOH? What would the pH and pOH be if the second H+ were also ionized?
Answers
1.
Zn + 2HCl → ZnCl2 + H23.
The O2− ion would come from H2O, which is not considered a classic acid in the Arrhenius sense.
5.2Al(OH)3 + 3 H2SO4 → Al2(SO4)3 + 6 H2O
7.
C8H10N4O2 + H2O → C8H10N4O2H+ + OH−; the H+ ion attaches to one of the N atoms in the caffeine molecule.
9.
As a strong acid or base, an amphiprotic substance reacts 100% as an acid or a base, so it cannot be a base or an acid at the same time.
11.
if the salt produced is an acidic salt
13.
NH3 + NH3 → NH4+ + NH2−15.
pOH > 7
17.
pH = −1.08; pOH = 15.08