Question

If the concentration of a saturated solution at 0∘C is 12.5 gCuSO4/100 g soln, what mass of CuSO4⋅5H2O would be obtained? [Hint: Note that the solution composition is stated in terms of CuSO4 and that the solid that crystallizes is the hydrate CuSO4⋅5H2O.]

Answer 1

Answer:

Mass of CuSO4.H2O obtained: $m_{total}=19.52 g$

Explanation:

The molecular weight of the salt is: $M=159.5 g/mol$

In the solution: 12.5 g of CuSO4

In moles: $n=\frac{12.5 g}{159.5 g/mol}=0.078 mol$

Mass of water:

5 moles of water per mol of salt: $m=\frac{5mol}{1mol}*0.078mol*\frac{18g}{mol}=7.02 g$

Mass of CuSO4.H2O obtained: $m_{total}=12.5 g + 7.02 g=19.52 g$