Unit 8 AP Chemistry

Which two species act as Brønsted–Lowry acids in the reaction?

• HPO₄²⁻ (aq) and OH⁻ (aq)

• H₂PO₄⁻ (aq) and HPO₄²⁻ (aq)

• HPO₄²⁻ (aq) and H₂O (l)

• H₂PO₄⁻ (aq) and H₂O (l)

Which species produced by the successive dissociations of phosphoric acid, H₃PO₄, are amphiprotic?

• HPO₄²⁻ and PO₄³⁻

• H₂PO₄⁻ and HPO₄²⁻

• H₂PO₄⁻ and PO₄³⁻

• HPO₄²⁻ only

Which is a conjugate Brønsted–Lowry acid-base pair?

• CH₃COO⁻ / H₃O⁺

• H₂O / CH₃COO⁻

• H₂O / H₃O⁺

• CH₃COOH / H₂O

Which species behave as Brønsted-Lowry acids in the following reversible reaction? H₂PO₄⁻(aq) + CN⁻(aq) ⇌ HCN(aq) + HPO₄²⁻(aq)

• HCN and CN⁻

• HCN and HPO₄²⁻

• H₂PO₄⁻ and

• HCN and H₂PO₄⁻

Which are definitions of an acid according to the Brønsted-Lowry and Lewis theories?

• A

• B

• C

• D

According to the Brønsted-Lowry theory, how does each species act in the equilibrium below? CH₃COOH + H₂SO₄ ⇌ CH₃COOH₂+ + HSO₄⁻

• A

• B

• C

• D

A student carried out a titration to determine the concentration of an acid and found that his value had good precision but poor accuracy. Which process explains this outcome?

• Consistently overshooting the volume of solution from the burette into the flask.

• Collection of insufficient titration data.

• Reading the meniscus in the burette at a different angle each time.

• Forgetting to rinse the flask after one of the titrations.

What will happen if the pressure is increased in the following reaction mixture at equilibrium? CO₂ (g) + H₂O (l) ⇌ H⁺ (aq) + HCO₃⁻ (aq)

• The equilibrium will shift to the right and pH will decrease.

• The equilibrium will shift to the right and pH will increase.

• The equilibrium will shift to the left and pH will increase.

• The equilibrium will shift to the left and pH will decrease.

A solution of acid HX has a pH = 1 and a solution of acid HY has a pH = 3. Which statement must be correct?

• HX is a stronger acid than HY.

• HY is a stronger acid than HX.

• The [H+] in the solution of HY is 100 times greater than the [H+] in the solution of HX.

• The [H+] in the solution of HY is 100 times greater than the [H+] in the solution of HX.

The pH of a solution changes from pH=2 to pH=5. What happens to the concentration of the hydrogen ions during this pH change?

• It decreases by a factor of 1000

• It increases by a factor of 1000

• It decreases by a factor of 100

• It increases by a factor of 100