Question

7. A mass of 2.50 g of blue, hydrated copper sulfate (CuSO4.xH2O). After heating, 1.59 g of white anhydrous copper sulfate(CuSO4) remains. What is the formula for the hydrate? Name the hydrate.

Answer 1

Answer:

The formula for the hydrate is CuSO₄.5H₂O and the name of the hydrate is Copper(II) Sulfate Pentahydrate.

Explanation:

Step 1 :

Calculate the mass of water ;

Mass of water = mass of hydrate - mass of anhydrous copper sulfate

                        = 2.50 g - 1.59 g

                        = 0.91 g

Step 2 :

Calculate the mass of water that combines with 1 mole of CuSO₄ ;

We know that the molar mass of CuSO₄ is 159.61 g/mole,

∴ Mass of water = 159.61 g CuSO₄ × 0.91 g H₂O ÷ 1.59 g CuSO₄

                           = 91.34 g H₂O

Step 3:

Calculate the moles of H₂O ;

Moles of water = 91.34 g H₂O × 1 mole H₂O ÷ 18.02 g H₂O  (∵ 1 mole water = 18.02 g H₂O )

                         ≅ 5 mole H₂O

∴ The formula for the hydrate is CuSO₄.5H₂O .