Question

Need help with this buffer question

A 1.00 liter solution contains 0.38 M hydrofluoric acid and 0.49 M sodium fluoride. If 0.120 moles of barium hydroxide are added to this system, indicate whether the following statements are true or false. (Assume that the volume does not change upon the addition of barium hydroxide.) VA. The number of moles of HF will increase. L B. The number of moles of F will increase. C. The equilibrium concentration of H30* will increase. _ D. The pH will decrease. _VE. The ratio of [HF] / [F] will decrease.

Answer 1

A. The number of moles of HF will increase.	False
B. The number of moles of F- will increase.	True
C. The equilibrium concentration of H3O+ will increase.	False
D. The pH will decrease.	False.
E. The ratio of [HF] / [F-] will decrease.	True

A. The number of moles of HF will decrease as with the addition of 0.12 M barium hydroxide(base), some HF will transfered into BaF2 salt.

B. The number of moles of F- will increase as formation of excess salt BaF2 will occured.

C. The equilibrium concentration of H3O+ will decreases as excess base neutralizes some acid.

D. The pH will increases as with the addition of 0.12 M barium hydroxide(base), some HF will transfered into BaF2 salt. As a result, the [H+] will decrease and consequently pH increases.

E. The ratio of [HF] / [F-] will decrease. Because, with the addition of 0.12 M barium hydroxide(base), some HF will transfered into BaF2 salt. Therefore, [HF] will decreases and [F-] increases .