CHEM 122A Exam 3 Review

Chapter 14

100

HNO₃ is a Brønsted-Lowry acid. Brønsted-Lowry acids _____________.

Donate an electron pair

Accept an electron pair

Are proton donors

Are proton acceptors

Are proton donors

200

What is the K_w of a solution when the [OH^-] is 0.05 M and the [H₃O⁺] is 0.002 M at 60°C?

0.0001

300

The [OH^-] of an acid is 0.005 M. What is the [H₃O⁺] in pure water at 60°C when K_w = 9.3x10^-14?

1.86 x 10^-11 M

400

Rank the compounds below in order of increasing acidity. Explain why in the justification below.

HF, H₂O, NH₃, CH₄

CH₄, NH₃, H₂O, HF

500

What mass of NH₄Cl must be added to 0.750L of a 0.100 M solution of NH₃ to give a buffer with the pH of 9.26? Assume negligible change in volume as solid is added.

NH₃(g) + H₂O(g) ⇌ NH₄⁺(g) + OH^-

K_b = 1.8 x 10^-5

4.01 g

Moar Chapter 14

100

NH3 is a is a Brønsted-Lowry base. Brønsted-Lowry bases _____________.

Donate an electron pair

Accept an electron pair

Are proton donors

Are proton acceptors

Are proton acceptors

200

What is the pH of stomach acid when [H₃O⁺] = 1.2x10-3 M?

2.92

300

What is the hydronium concentration in a 0.175 M solution of HNO₂ and 0.30M of sodium nitrate?

HNO₂ (aq) + H₂O (l) ⇌ H₃O⁺ (aq) + NO₂^- (aq)              

K_a = 4.6 x 10^-5

 

2.68 x 10^-5 M

400

Calculate the pH and pOH when the [H₃O⁺] is 5x10^-8 M.

pH = 7.30 ; pOH = 6.69

500

A titration is carried out for 25.00 mL of 0.200 M HCl (strong acid) with 0.200 M NaOH (strong base). Calculate the pH after 12.5 mL of NaOH is added.

 

1.176

Bring Back My Chapter 14

100

Identify the Brønsted-Lowry acid/base and their conjugates.

CH₃CO₂ (aq) + H₂O (l) ⇌ CH₃CO₂H (aq) + OH^- (aq)

Acid: H₂O; Conj. Base: OH^-

Base: CH₃CO₂; Conj Acid: CH₃CO₂H

200

Calculate the concentration of hydronium in blood when the pH=7.3.

5.0118 x 10^-8 M

300

Determine the acetic acid concentration, [CH₃CO₂H], in a solution with [CH₃CO₂^-] = 0.075 M and [OH^-] = 2.5 x 10^-6 M at equilibrium. K_a for [CH₃CO₂H] = 1.8 x 10^-5

CH₃CO₂ (aq) + H₂O (l) ⇌ CH₃CO₂H (aq) + OH^- (aq)

1.67 x 10^-5 M

400

What is the pH of the buffer solution prepared from 0.40 mol NH₃, 0.80 mol NH₄NO₃ and just enough water for a 1.00L solution?

NH₃(g) + H₂O(g) ⇌ NH₄⁺(g) + OH^-

K_b = 1.8 x 10^-5

8.96

500

What are [H3O⁺], [HCO₃^-], and [CO₃^2-] in a saturated solution of CO₂ with an initial [H₂CO₃] = 0.025 M?

H₂CO₃(aq) + H₂O(l) ⇌ H₃O⁺ (aq)+ HCO₃⁻ (aq) K_a1=4.3× 10⁻⁷

HCO₃⁻(aq) + H₂O(l) ⇌ H₃O⁺ (aq)+ CO₃²⁻ (aq)    K_a2=4.7 × 10⁻¹¹

[H₃O⁺], [HCO₃^-] = 1.04 x 10^-4 M ; [CO₃^2-] = 4.7 x 10^-11 M