Question

Determine the percentage of water of crystallization in a sample of green vitriol.

• A. $45.32\%$
• B. $31.26\%$
• C. $22.59\%$
• D. $75.45\%$

Answer 1

The correct option is A $45.32\%$

Molecular formula of green vitriol is $FeS{O}_4.7H_{2}O.$

Formula mass = $56+32+(4\times 16)+(7\times (2+16\left)\right)=278\text{amu}$

Mass of water of crystallization $=7\times 18=126\text{amu}$

% of water of crystallization $=\left(126/278\right)\times 100=45.32\%$