Biochem Quiz 1's

IIf 2.0 mL of a solution, having a pH of 1, is diluted to a volume of 100 mL, the pH of the new solution is ___

Which solution would be expected to have the highest pH?
A) 0.1 M NH4Cl
B) 1 M HCl
C) 0.1 M HOAc
D) 0.1 M NaOAc
H20

A solution of sodium bicarbonate would be expected to have a pH > 7 because ___. (NOTE: Sodium benzoate is the sodium salt of benzoic acid - pKa = 4.6.)

Which ion would be expected to have the largest hydrolysis constant (K@h)? (NOTE: propionic acid (HPro) - Ka = 3.2 x 10^-5, benzoic acid (HOBZ) - Ka = 1.5 x 10^-5, acetic acid (HOAc) - Ka - 1.8 x 10^-5, formic acid (HForm) - Ka = 1.8 x 10^-4)
A) OBz-
B) OAc-
C0 Cl-
D) Form-
E) Pro-

Estimate the pH of a solution prepared by adding 100 mL of H2O to 100 ml of an acetic acid/sodium acetate buffer which has an initial (HOAc) = 0.2 M and an initial (OAc-) = 0.2 M. NOTE: See Q#4 for the Ka value for the proton donor in this case.
(H+)buffer=Ka x [(OAc-)/(HOAc)]

Which of the following solutions would have a pH which is more acidic than a solution having a pH of 8.27
A) pH = 8.4
B) pH = 12.1
C) pH = 9.2
D) pH = 7.4
E) pH = 9.8

If one dilutes 10 ml of a solution of HCl, with an initial pH of 2, to a total volume of 1 liter (1000 ml), what is the pH of the system after dilutions?

Which of the following acids is the 'weakest'?
A) HB (pKa = 3)
B) HC Ka = 6 x 10^-5)
C) HA (Ka = 1 x 10^-4)
D) HG (2.5 x 10^-4)
E) HD (pKa = 6)

Which of the following reactions takes place to a significant extend when NH4Cl is dissolved in water?
A) NH3 + H2O --> NH4+ + OH-
B) NH4OH --> NH4+ + OH-
C) NH3 --> NH2- + H+
D) NH4+ + H2O --> NH3 + H30+
E) Cl- + H2O --> HCl

The Henderson0Hasselbach equation used to calculate the pH of a buffer for which the proton donor is H2A and the proton acceptor os HA- would look like: pH = ___

A system having a pH of 4.7 will have a hydrogen ion concentration equal to ___.

Complete the reaction: NH3 {g} + H2O --> ___{ag} + OH-{ag}

Estimate the pKa for the weak acid HA, if a 0.01 M solution of the acid has a pH of 4.

Which of the following 'salt' solutions will have the lowest pH?
A) NH4Cl
B) Na2CO3
C) KClO4
D) NaHCO3
E) NaC2H3o2 (sodium acetate)

The addition of 1 ml of 6 M HCl to a solution containing 50 moles of acetic acid and 50 moles of sodium acetate will cause the pH of the solution to ___.

A strong base dissociates 100% to yield ___.

If a 0.1 M solution of the acid HA, has a pH of 2.5, and a 0.1 M solution weak acid HB has a pH of 3.5, then HA is the ___ acid because it dissociates to a ___.

A salt which is classified as 'acidic' is formed by a reaction between a ___.

Which of the following represents the expression for the Kh associated with NH4Cl?

Calculate the pH of a buffer solution for which (HC7H5O2) - 0.12 M and (C7H5O2-) - 0.19 M. NOTE: pKa for (HC7H5O2) is 4.5.

Which of the following species will always result from the dissociation of a strong base?
A) H3O+
B) H-
C) H2O
D) H+
E) OH-

If a solution has a pH of 3, then the (OH-) for that solution will equal ___.

An 'acidic salt' is formed from the reaction between a ___ and a ___.

If solution 'A' has a (H+) = 1 x 10^-3 M, and 10 ml of 'A' is diluted to 100 ml to prepare solution 'B', and 10 ml of 'B' is diluted to 100 ml to prepare solution 'C', what is the pH of solution 'C'?

If a weal acid, HA, has a Ka = 2 x 10^-5, then the hydrolysis constant, Kh, for the salt NaA is ___.

Which of the following substances is the weakest acid?
A) HX (Ka = 2 x 10^-7)
B) HD (Ka = 5 x 10^-6)
C) HB (Ka = 1 x 10^-5)
D) HA (Ka = 1 x 10^-3)
E) HC (Ka = 1 x 10^-9)

If a solution XX has a pH of 4.6 and solution YY has a pH of 4, then the (H+) in solution XX is ___ the (H+) in solution YY.

Flask A contains a 0.1 M solution of a strong acid. 10 ml of the solution from flask A are diluted to 100 ml and placed in flask B. 25 ml of the solution from flask B are diluted to 100 ml and place in flask C. What is the pH of the solution in flask C?

A 'salt' derived from the reaction between a strong base and a weak acid (e.g. NaC2H3O2) has a pH ___ 7 because, in solution, the anion behaves as though it were a ___.

If a buffer is prepared by dissolving one mole of a weak acid, and one mole of conjugate base in a liter of water, the pH of the buffer will be equal to the ___.