Answer:
A)true
B)false
C)true
D)false
E)false
Explanation:
Step 1: Data given
Volume = 1.00 L
Number of moles HCN = 0.49 moles
Number of moles NaCN = 0.38 moles
Number of moles HCl added = 0.19 moles
Step 2:
This is a buffer system consisting of a weak acid, HCN and the salt of that acid, NaCN.
Upon addition of hydrochloric acid (HCl), HCN is formed and NaCl is used up.
HCl + NaCN ⇔ NaCl + HCN
A. The number of moles of HCN will increase. This is true.
B. The number of moles of CN- will increase.
⇒ false, The number of moles of CN- will decrease b/c it is now part of HCN, a weak acid.
C. The equilibrium concentration of H3O will increase.
⇒ True, The [H3O+] will increase slightly.
D. The pH will increase.
⇒ False, The pH will decrease slightly because acid is being added and being converted to HCN
E. The ratio of [HCN] / [CN-] will remain the same.
⇒ False. It will increase.
