Question

A 1.547 g sample of blue copper(II) sulfate pentahydrate, ‍ , is heated carefully to drive off the water. The white crystals of that are left behind have a mass of g. How many moles of ‍ were in the original sample? Show that the relative molar amounts of and ‍ agree with the formula of the hydrate.

Answer 1

`=6.2x10^(-3)mol CuSO_4`

Step-by-step explanation:

Hello,

By developing the following stoichiometric relationship, the required amount could be found as follows:

- Moles of
`CuSO_4`:

`1.547gCuSO_4.5H_2O *(1molCuSO_4.5H_2O)/(249.5gCuSO_4.5H_2O) *(1mol CuSO_4)/(1mol CuSO_4.5H_2O) =6.2x10^(-3)mol CuSO_4`

- Grams of
`CuSO_4`

`1.547gCuSO_4.5H_2O *(1molCuSO_4.5H_2O)/(249.5gCuSO_4.5H_2O) *(1mol CuSO_4)/(1mol CuSO_4.5H_2O)*(159.5g CuSO_4)/(1mol CuSO_4) =0.989 g CuSO_4`

- Moles of water:

`1.547gCuSO_4.5H_2O *(1molCuSO_4.5H_2O)/(249.5gCuSO_4.5H_2O) *(5mol H_2O)/(1mol CuSO_4.5H_2O)=0.031mol H_2O`

Finally, one could see that the mass of the anhydrous compound is less than the pentahydrated compound since it is waterless.

Best regards.