Question

A hydrate of CoCl2 with a mass of 6.00g is heated strongly. After cooling, the mass of the anhydrate is 3.27g. What is the formula of the CoCl2 hydrate?

Answer 1

Hope this helps. I used this for mine and it worked for me!

Answer 2

Answer : The formula for the $CoCl_2$ hydrate is $CoCl_2.6H_2O$

Explanation : Given,

Mass of hydrate of $CoCl_2$ = 6.00 g

Mass of $CoCl_2$ = 3.27 g

First we have to calculate the mass of water.

Mass of water = Mass of hydrate of $CoCl_2$ - Mass of $CoCl_2$

Mass of water = 6.00 - 3.27 = 2.73 g

Now we have to calculate the moles of $CoCl_2\text{ and }H_2O$

Molar mass of $CoCl_2$ = 129.8 g/mole

Molar mass of $H_2O$ = 18 g/mole

$\text{ Moles of }CoCl_2=\frac{\text{ Mass of }CoCl_2}{\text{ Molar mass of }CoCl_2}=\frac{3.27g}{129.8g/mole}=0.0252moles$

and,

$\text{ Moles of }H_2O=\frac{\text{ Mass of }H_2O}{\text{ Molar mass of }H_2O}=\frac{2.73g}{18g/mole}=0.152moles$

Now we have to calculate the mole ratio of the given molecules.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.0252 moles.

For $CoCl_2$ = $\frac{0.0252}{0.0252}=1$

For $H_2O$ = $\frac{0.152}{0.0252}=6.03\approx 6$

The ratio of $CoCl_2:H_2O=1:6$

Hence, the formula for the $CoCl_2$ hydrate is $CoCl_2.6H_2O$