How many total moles of ions are released when each of the following samples dissolves completely in water?

Question

A) .21 mol of NaCl
B) 23.7 g of Ba(OH)2 * 8 H2O
C) 1.63 x 10^20 formula units of LiCl
D) .342 mol of K2HPO4

Answer 1

A) NaCl contains two ions, so 2 * 0.21 moles = 0.42 moles of ions.

B) each FW contains 3 ions, so 23.7 g / 315.5 g/FW = 0.075 FW
3 * 0.075 FW = 0.225 moles of ions.

C) each unit contains 2 ions, so 1.63 X 10^20 * 2 = 3.26 X 10^20 moles of ions

D) K2HPO4 is tricky. It is very soluble in water but:

K2HPO4 --> 2 K+ + (HPO4)-2 only three ions.

0.342 moles * 3 = 1.026 moles of ions.