Question

A hydrate sample of magnesium chloride is analyzed and found to contain $53.18$% water.
How many water molecules are found in the formula for this hydrate?

• A. Two
• B. Four
• C. Six
• D. Eight

Answer 1

The correct option is A Two

$\begin{array}{c}\text{Let, the hydrated sample contains}x\text{molecules of}{H}_{2}O\text{.}\\ \text{so, given sample becomes}{MgCl}_2\cdot x{H}_{2}O\text{.}\\ \text{Now, it is given that}53.18\%\text{of the formula is}{H}_{2}O\text{.}\end{array}$

$\begin{array}{c}\text{Thus,}\frac{x\times 18}{(18x+95)}=\frac{53.18}{100.}\Rightarrow x=6\\ \text{Hence, there are six water molecules are found in this hydrate.}\end{array}$