# A chemist wants to extract the gold from 15.0g of gold(II) chloride dihydrate, AuCl_3.2H_20, What...

## Question:

A chemist wants to extract the gold from 15.0g of gold(II) chloride dihydrate, {eq}AuCl_3 \cdot 2H_20 {/eq}, What mass of gold could be obtained from this sample?

## Molar Mass:

During dimensional analysis, we will, more often than not, need to make use of the molar mass of substances. This would be the case especially for problems that concern the number of products in a given reaction. This is because the molar mass is a quantity which relates the total mass of a substance per mole.

Determine the yield in terms of the mass of the gold by extracting from the given hydrate by first finding the number of moles there is in the given amount of substance, then we multiply the ratio of the number of moles of gold there is in the given compound and finally we multiply the molar mass of gold. We proceed with the solution.

{eq}\begin{align} \displaystyle 15.0\ g\ AuCl_3\cdot 2H_2O \times \frac{1}{339.3561}\rm{mol/g}\cdot \frac{1\ mol\ Au}{1\ mol\ AuCl_3\cdot 2H_2O}\cdot 196.96657\ \rm{g/mol} =8.71\ g\ Au \end{align} {/eq}