Midterm exam-4

Which of the following pairs of compounds dissolved together in aqueous solution would NOT make a good buffer solution?

• HNO₃/NaNO₃

• H₃PO₄/NaH₂PO₄

• H₂CO₃/KHCO₃

• HCN/KCN

A solution is prepared which is 1.0 M acetic acid. What would happen to the pH of this solution if potassium acetate were added to the solution?

• pH would go up

• pH would go down

• would not affect the pH

A buffer solution is prepared by the addition of 5.0 grams of HF and 22.0 grams of NaF to enough water to make 1.000 L of solution. The K_a of HF is 7.2 x 10^-4. What is the pH of this solution?

• 7.00

• 3.46

• 3.87

• 2.09

A buffer solution is 0.10 M HAc (acetic acid) and 0.10 M NaAc (sodium acetate) and we have 1.000 Liter of it. What is the pH after 0.010 moles of HCl are added to this solution? Ka = 1.8 x 10^-5

• 4.74

• 3.22

• 4.65

• 4.82

What ratio of NH₄Cl / NH₃ should be used to give a buffer with pH = 8.50? K_b of NH₃ = 1.8 x 10^-5.

• 1.3

• 4.67

• 5.90

• 5.7

Which salt would produce a solution with a pH significantly greater than 7.0?

• NH₄Cl

• NaOCl

• KCl

• NaI

Which of the following anions is the strongest base?

• ClO^-

• I^-

• Cl^-

• ClO₄^-

Which one of the following salts produces neutral solutions when it is dissolved in water?

• NaCN

• NaOCl

• NaF

• NaBr

When a strong acid is titrated with a weak base, the pH at the equivalence point is ALWAYS __________.

• 7

• <7

• >7

• >4

Calculate the pH of a solution when 20.0 mL of a 0.100 M NaOH is added to 25.0 mL of 0.100 M HCl.

• 1.67

• 9.0

• 4.32

• 1.95