Determine whether or not the mixing of each pair of solutions results in a buffer. Show all work!

a.) 75.0 mL of 0.10 M HF; 55.0 mL of 0.15 M NaF

b.) 150.0 mL of 0.10 M HF; 135.0 mL of 0.175 M HCl

c.) 165.0 mL of 0.10 M HF; 135.0 mL of 0.050 M KOH

d.) 125.0 mL of 0.15 M CH3NH2; 120.0 mL of 0.25 M CH3NH3Cl

e.) 105.0 mL of 0.15 M CH3NH2; 95.0 mL of 0.10 M HCl

a) Acidic buffer

b) No buffer

c) Acidic buffer

d) Basic buffer

e) Basic buffer

Explanation:

a) 75.0 mL of 0.10 M HF; 55.0 mL of 0.15 M NaF - Acidic buffer

Mixing of 75.0 mL of 0.10 HF and 55.0 mL of 0.15 mL NaF results in acidic buffer. HF/NaF is a buffer of weak acid and its conjugate base. F - is the conjugate base of acid, HF.

b.) 150.0 mL of 0.10 M HF; 135.0 mL of 0.175 M HCl-No buffer

Mixing HF and HCl will not results in a buffer. Both are acids, and no conjugate base is present.

c.) 165.0 mL of 0.10 M HF; 135.0 mL of 0.050 M KOH-Acidic buffer

HF reacts with KOH to form KF. F - is a conjujate base of HF. As volume and concentration of HF is more than KOH, therefore, HF will remain after reaction with KOH. HF/KF will be a buffer of weak acid and its conjugate base.

d.) 125.0 mL of 0.15 M CH3NH2; 120.0 mL of 0.25 M CH3NH3Cl - Basic buffer

CH3NH2/CH3NH3 + is a buffer of weak base and its conjugate acid.

e.) 105.0 mL of 0.15 M CH3NH2; 95.0 mL of 0.10 M HCl-Basic buffer

CH3NH2 is a weak base and HCl is a strong acid. CH3NH2 reacts with HCl to form its conjugate acid CH3NH3+. Volume and concentration of CH3NH2 is more as compared to HCl and hence, will remain in the soution after reactionf with HCl.

CH3NH3+/CH3NH2 is a buffer of weak base and its conjugate acid.