Chem Exam 3

Which of the following bases is the strongest? The base is followed by its Kb.

(CH3CH2)2NH, 8.6 × 10^-4

Determine the [OH⁻] concentration in a 0.169 M Ca(OH)2 solution.

.338 M

A 100.0 mL sample of 0.18 M HClO4 is titrated with 0.27 M LiOH. Determine the pH of the solution before the addition of any LiOH.

0.74

What is the concentration of hydroxide ions in pure water at 30.0∘C, if Kw at this temperature is 1.47 × 10^-14

1.21 × 10^-7 M

Determine the molar solubility of PbSO4 in pure water. Ksp (PbSO4) = 1.82 × 10^-8.

1.35 × 10^-4 M

Calculate the concentration of H3O⁺ in a solution that contains 6.25 × 10-9 M OH⁻ at 25°C. Identify the solution as acidic, basic, or neutral.

1.60 × 10^-6 M, acidic

Determine the molar solubility of BaF2 in pure water. Ksp for BaF2 = 2.45 × 10^-5.

1.83 × 10^-2 M

Calculate the hydroxide ion concentration in an aqueous solution with a pH of 4.33 at 25°C.

2.1 × 10^-10 M

Determine the pH of a 0.00598 M HClO4 solution

2.223

Determine the pH of a 0.461 M C6H5CO2H M solution if the Ka of C6H5CO2H is 6.5 × 10-5.

2.26

A container of orange juice at 25°C has a hydronium concentration of 1.78 × 10-3M. What is the pH of the juice?

2.75

Determine the molar solubility of AgBr in a solution containing 0.150 M NaBr. Ksp (AgBr) = 7.7 × 10^-13

5.1 × 10^-12 M

What is the Kw of pure water at 50.0°C, if the pH is 6.630?

5.50 × 10^-14

Calculate the pOH in an aqueous solution with a pH of 7.85 at 25°C.

6.15

Determine the molar solubility for Pb3(PO4)2 in pure water. Ksp for Pb3(PO4)2 is 1.0 × 10^-54.

6.2 × 10^-12 M

Calculate the pOH of a solution that contains 2.4 × 10^-8 M H3O⁺ at 25°C.

6.38

A 100.0 mL sample of 0.10 M Ca(OH)2 is titrated with 0.10 M HBr. Determine the pH of the solution after the addition of 200.0 mL HBr.

7.00

Calculate the hydronium ion concentration in an aqueous solution with a pOH of 9.85 at 25°C.

7.1 × 10^-5 M

What is the hydronium ion concentration of a 0.150 M hypochlorous acid solution with The equation for the dissociation of hypochlorous acid is:

7.2 × 10^-5 M

Calculate the pH of a solution formed by mixing 100.0 mL of 0.20 M HClO with 200.0 mL of 0.30 M KClO. The Ka for HClO is 2.9 × 10^-8.

8.01

Determine the Ka of an acid whose 0.294 M solution has a pH of 2.80.

8.5 × 10^-6

Determine the [H3O⁺] in a 0.265 M HClO solution. The Ka of HClO is 2.9 × 10^-8.

8.8 × 10^-5 M

Calculate the pH of a solution formed by mixing 250.0 mL of 0.15 M NH4Cl with 100.0 mL of 0.20 M NH3. The Kb for NH3 is 1.8 × 10^-5.

8.98

Calculate the pH of a buffer that is 0.200 M H3BO3 and 0.122 M KH2BO3. The Ka for H3BO3 is 5.8 × 10^-10.

9.02

If a chemist wishes to prepare a buffer that will be effective at a pH of 3.00 at 25°C, the best choice would be an acid component with a Ka equal to

9.10 × 10^-4.

Which of the following is TRUE?

A buffer is most resistant to pH change when [acid] = [conjugate base]

Which of the following is TRUE?

An acidic solution has [H3O⁺] > [OH⁻]

Define buffer capacity.

Buffer capacity is the amount of acid or base that can be added to a buffer without destroying its effectiveness

All of the following anions are considered basic EXCEPT

Cl^-

What is the conjugate acid of HCO3

H2CO3

is found in carbonated beverages due to the reaction of carbon dioxide with water.

H2CO3

Identify the weak diprotic acid.

H2SO3

Identify the acid that is in car batteries.

H2SO4

Which of the following is an Arrhenius acid?

H2SO4

Identify the triprotic acid.

H3PO4

Which of the following acids will have the strongest conjugate base?

HCN

Which of the following solutions would have the highest pH? Assume that they are all 0.10 M in acid at 25∘C. The acid is followed by its Ka value.

HCN, 4.9 × 10^-10

The stomach excretes ________ to kill microorganisms and to activate enzymes that break down food.

HCl

Which of the following solutions would have the lowest pH? Assume that they are all 0.10 M in acid at 25∘C. The acid is followed by its Ka value.

HClO2, 1.1 × 10^-2

Identify the weakest acid

HF

Which of the following acids is the weakest? The acid is followed by its Ka value

HIO, 2.3 × 10^-11

What is the conjugate base of H2PO4⁻

HPO4^(2-)

Which of the following species is amphoteric?

HPO4^2-

Describe the information necessary (and why) to chose a good indicator for a weak acid/strong base titration.

In order to choose an appropriate indicator, you must know what the pH should be at the equivalence point of your titration. For a weak acid/strong base, the pH would be basic. The pKa of the indicator chosen should be very close to the pH of the titration's equivalence point.

In a triprotic acid, which Ka has the highest value?

Ka1

An aqueous solution of ammonia is found to be basic. This observation can be explained by the net ionic equation

NH3(aq) + H2O(l) → NH4+(aq) + OH-(aq)

Which of the following is a Brønsted-Lowry acid?

NH4+

Identify the base that is in baking soda.

NaHCO3

Identify the base that is in Drano.

NaOH

Do both protons ionize instantaneously from a diprotic acid such as H2CO3? Explain your answer

No because Polyprotic acids only ionize in a sequence of stages. A small piece of the first protons ionize, then the second ionization. In order to have the second proton loss when a small amount of the acid molecules have already lost their first ionized hydrogen ion.

Give the equation for a saturated solution in comparing Q with Ksp.

Q = Ksp

Which of the following is TRUE?

The equivalence point is where the amount of acid equals the amount of base during any acid-base titration.

If the pKa of HCHO2 is 3.74 and the pH of an HCHO2/NaCHO2 solution is 3.74, which of the following is TRUE?

[HCHO2] = [NaCHO2]

If the pKa of HCHO2 is 3.74 and the pH of an HCHO2/NaCHO2 solution is 3.11, which of the following is TRUE

[HCHO2] > [NaCHO2]

A Lewis Acid

accepts electrons

An important buffer in the blood is a mixture of

carbonic acid and bicarbonate ion.

A lewis base

donates electrons

Give the characteristics of a strong acid.

has a polar bond has a weaker bond to hydrogen ionizes completely in aqueous solutions has equilibrium far to the right >>>>all of the above

Which of the following weak acids has the strongest conjugate base?

hydrocyanic acid, Ka = 4.0 × 10^-10

Sketch the titration curve for a monoprotic weak acid titrated with a strong base. Make sure to indicate the equivalence point (and whether it is acidic, basic or neutral) and the buffer region.

look at your pictures

Sketch the titration curve for a strong acid titrated with a strong base. Make sure to indicate the equivalence point (and whether it is acidic, basic or neutral) and the buffer region.

look at your pictures

When titrating a strong monoprotic acid with KOH at 25°C, the

pH will be equal to 7 at the equivalence point

When titrating a weak monoprotic acid with NaOH at 25°C, the

pH will be greater than 7 at the equivalence point.

When titrating a monoprotic strong acid with a weak base at 25°C, the

pH will be less than 7 at the equivalence point.

Identify a good buffer

significant amounts of both a weak acid and its conjugate base