Copper(II) Sulfate Pentahydrate: CuSO4•5H2O
Molar Mass: 63.55g/mol + 32.07g/mol + 4(16.00)g/mol + 10(1.01)g/mol + 5(16.00)g/mol = 249.72g/mol
Mass of Water Molecules: 10(1.01)g/mol + 5(16.00)g/mol = 90.10g/mol
Percent Water: 90.10g/mol / 249.72g/mol • 100 = 36.08%
Manganese(II) Chloride Tetrahyrate: MnCl2•4H2O
Molar Mass: 54.94g/mol + 2(35.45)g/mol + 8(1.01)g/mol + 4(16.00)g/mol = 197.92g/mol
Mass of Water: 8(1.01)g/mol + 4(16.00)g/mol = 72.08g/mol
Percent Water: 72.08g/mol / 197.92g/mol •100 = 36.42%
Zinc Sulfate Heptahydrate: ZnSO4•7H2O
Molar Mass: 65.38g/mol +32.07g/mol + 4(16.00)g/mol + 14(1.01)g/mol + 7(16.00)g/mol = 285.59g/mol
Mass of Water: 14(1.01)g/mol + 7(16.00)g/mol = 126.14g/mol
Percent Water: 126.14g/mol / 285.59g/mol •100 = 44.17%
Percent Error Equation:
\(\%\ Error\ =\ \frac{\left|Approx-Exact\right|}{Exact}\cdot100\)
\(\%\ Error\ =\ \frac{\left|28\%-36.08\%\right|}{36.08\%}\cdot100\)
\(\%\ Error\ =\ \frac{8.08}{36.08}\ \cdot100\)
\(\%\ Error\ =22.3\%\ \sim22\%\)