A weighed portion of 161 g of Glauber’s salt Na2S04 • YH20 was dissolved in 180 l of water.

A weighed portion of 161 g of Glauber’s salt Na2S04 • YH20 was dissolved in 180 l of water. Calculate the mass fraction of sodium sulfate in the resulting solution. How many ions of each type are in it?

Solution:
1) The mass of the solution after dissolution is 161 + 180000 = 180161 g
2) 322 g of salt – 142 g of Na2S04 (based on M)
161 g salt – x g Na₂
X = 142 * 161/322 = 71 g
3) w (Na₂S0₄) = 71/180161 = 0.00039 = 0.039%
4) n (Na₂S0₄) = 71/142 = 0.5 mol
5) n (Na) = 2n (Na₂S0₄) = 1 mol
6) n (S0₄) = n (Na₂S0₄) = 0.5 mol.
Answer: 0.039%, 1 mol, 0.5 mol