Question

For hydrated copper (II) sulfate calculate the mass percentage of water in your hydrated crystals.

Answer 1

56.44 %

Step-by-step explanation:

The formula of copper(II) sulfate pentahydrate is
`CuSO_4\cdot 5H_2O`.

In order to calculate the mass percentage of water in it, we may assume that we have 1 mol of copper(II) sulfate pentahydrate. In general, the mass percentage is a ratio between the mass of a component and the total mass of the compound expressed in percent:

`\omega = (m_c)/(m_t)\cdot 100 \%`

Since we're taking 1 mole of a substance here, we may state that the mass percentage of water will be calculating using molar masses instead:

`\omega_(H_2O) = (5M_(H_2O))/(M_(CuSO_4\cdot 5 H_2O))\cdot 100 \%`

Notice that we take 5 molar masses of water, as 1 mole of copper(II) sulfate pentahydrate contains 5 moles of water molecules, then:

`\omega_(H_2O) = (5\cdot 18.016 g/mol)/(159.609 g/mol)\cdot 100 \% = 56.44 \%`