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# The percentage of water of crystallization in ZnSO4. 7H2O is...

### Question

The percentage of water of crystallization in ZnSO4. 7H2O is

A) 33%

B) 44%

C) 55%

D) 87%

## Discussion (4)

• Molecular mass of ZnSo4.7H2O = 65 + 32 + 16 × 4 + 7(1 × 2 + 16)
= 97 + 64 + 126
= 287 grams.

Mass of Water of crystallization inZnSo4.7H2O (7H2O) = 7 × 18
= 126 grams.
Using the Formula,

% of Water of Crystallization
= (Mass of Water of Crystallization/Mass ofZnSo4.7H2O) × 100
= (126/287) × 100
= 43.91%.

Thus, the % of Water of Crystallization inZnSo4.7H2O is 43.91%.

• Zn= 65, S=32, O= 16
The molar mass of water is:
7(2)+7(16)= 126g/mol
The molar mass of the compound is:
65+32+4(16)+7(2)+7(16)= 287g/mol
Then the percentage of water is:
126/287×100 =43.9%~44%

• Fasina Nathaniel

m.m of ZnSO4.7H20= 287
mm of 7H20=126
126/287*100= 43.9
Approximately=44%

• Mm of Zn≈65
7(H₂O) = 126
Mm of ZnSO₄ ≈ 161
% of Water of crystallization;
= 126
------------- • 100
(126)+(161)
≈44%