Chem Test acid/base

the gas that is produced when alkali metals react with water

Hydrogen

The hydronium ion concentration [H3O+] of a fruit juice is 2.5 · 10⁻⁵ M. What is the pH of the juice? a. 1.5 b. 5.5 c. 2.5 d. 4.6

-log[H3O+] = pH → -log(2.5e-5) = 4.6 The correct answer is: 4.6

A neutral solution contains more hydroxide ions (OH-) than hydronium ions (H₃O+). True or False

A neutral solution contains an equal concentration of hydroxide ions and hydrogen ions. these are equal when the solution is neutral. False

Calculate the pOH of a 0.410 M Ca(OH)2 solution. a. 13.9 b. 0.178 c. 0.387 d. 0.0862

Ca(OH)2 → Ba2+ + 2 OH- 0.410 M → 0.820 M OH- -log[OH-] = pOH = -log(0.82) = 0.0862 The correct answer is: 0.0862 d. 0.0862

Acid solutions taste bitter and basic solutions taste sour. True or False

False

An acidic solution contains more hydroxide ions (OH-) than hydronium ions (H3O+). True or False

False

An aqueous solution of acid causes litmus paper to turn blue. True or False

False

Calculate pH of an aqueous solution of 8.75 · 10⁻⁷ M HCl. a. 7.85 b. 7.77 c. 8.61 d. 6.06

HCl + H2O → Cl- + H3O+ for strong acids (like HCl), the acid ionizes 100% into hydronium, so you can use the starting concentration of acid to find the hydronium formed pH = -log[H3O+] = -log(8.75e-7) = 6.06 The correct answer is: 6.06

Given the same concentration, a weak acid produces fewer ions than a strong acid. True or False

True

In solution, strong acids and bases ionize completely, but weak acids and bases ionize only partially. True or False

True

acids turn litmus paper red True or False

True

bases turn litmus paper blue True or False

True

the concentration equilibrium constant (Kb) for a weak base has

a nonzero value in its denominator

the concentration equilibrium constant (Ka) for a strong acid has

a zero in its denominator

substances that increase the concentration of hydronium [H₃O⁺]

acids

The relative amounts of hydronium ions (H3O+) and hydroxide ions (OH-) determine whether an aqueous solution is acidic, basic or neutral. True or False

acids increase hydronium ions (H3O+) while bases increase hydroxide ions (OH-) The correct answer is 'True'.

A basic solution contains more _____ than ______ . a. oxygen, hydrogen b. hydroxide, hydronium c. hydronium, hydroxide d. hydrogen, oxygen

b. hydroxide, hydronium

A solution that contains equal concentrations of hydroxide ions (OH-) and hydronium ions (H₃O+) is _____. a. an acid b. neutral c. a base d. ionized

b. neutral

substances that increase the concentration of hydroxide [OH⁻]

bases

if HCl is added to pure water, then pH is

between 0 and 7

if KOH is added to pure water, then pH is

between 7 and 14

Calculate the hydronium ion concentration [H₃O+] of an aqueous solution, given the concentration of hydroxide ions [OH-] = 1 x 10⁻⁵ M, and the ion constant for water (Kw) = 10⁻¹⁴ a. 10⁻⁴ M b. 10⁻¹⁹ M c. 10⁻⁹ M d. 10⁻¹⁴ M

c. 10⁻⁹ M [H3O+][OH-] = Kw = 10-14 [H3O+] = 10-14 / [OH-] = 10-14 / 10-5 = 10-9 M [H3O+] The correct answer is: 10-9 M

What is the pH of 20.00 g of KOH in 350.0 mL of water? a. -0.008 b. 1.02 c. 14.01 d. 0.0000045

c. 14.01 20 g KOH / (56.1 g / mol) = 0.3565 mol KOH / 0.35 L = 1.02 M KOH = [OH-] -log[OH-] = pOH = -log(1.02) = -0.008 pH + pOH = 14 → pH = 14 - (-0.008) = 14.008 The correct answer is: 14.01

How many liters of water would be necessary to make a solution with 1 gram of calcium hydroxide and a pH = 10.45?

convert pH into [OH-] → 14 - pH = 3.55 = pOH = -log[OH-] → 10-pOH = [OH-] → [OH-] = 2.82e-4 M since Ca(OH)2 gives 2 [OH-] for each formula unit, this means 2.82e-4 / 2 = mol Ca(OH)2 needed per liter = 1.41e-4 mol / L 1 g Ca(OH)2 / 74.1 g / mol Ca(OH)2 = 0.0135 mol Ca(OH)2 given in one gram 0.0135 mol / x L = 1.41e-4 mol / L → x = 0.0135 mol / (1.41e-4 mol / L) = 95.77 L The correct answer is: 95.77

An aqueous solution has a pH of 2.7 at 298 K. Calculate the pOH of the aqueous solution. a. 12 b. 9.3 c. 17 d. 11

d. 11 pH + pOH = 14 → pOH = 14 - pH = 14 - 2.7 = 11.3

Which of the following is not a strong acid? a. HClO₄ b. HCl c. HNO₃ d. H₃AsO₄ e. HBr

d. H₃AsO₄ strong acids: HBr, HCl, HI, H2SO4, HNO3, HClO4 The correct answer is: H3AsO4

if an equal amount of KOH and HCl were added to pure water, then pH is

equal to 7

If a solution has a pOH = 9.23, calculate the molar hydronium concentration [H₃O+] a. 9.3 · 10⁻³ M b. 5.9 · 10⁻¹⁰ M c. 4.8 · 10⁻³M d. 2.1 · 10⁻⁷ M e. 1.7 · 10⁻⁵ M

pOH = -log[OH-] → 10-pOH = [OH-] → 10-9.23 = 5.9e-10 M OH- Kw = [H3O+][OH-] = 10-14 → [H3O+] = 10-14 / [OH-] → [H3O+] = 10-14 / (5.9 · 10-10) [H3O+] = 1.7 · 10-5 M The correct answer is: 1.7 · 10-5 M