WAEC - Chemistry (2013 - No. 21)
The percentage by mass of calcium in Ca(OCI)2 is [Ca = 40.0; CI = 35.5; O = 16.0]
28.0%
31.6%
43.8%
44.5%
Explanation
Molar mass of \(Ca(OCl)_2\) = 40 + (16 + 35.5)x2 = 143
% by mass of calcium in the compound =\(\frac{mass of calcuim}{molar mass of compound}\) x 100%
% calcium = \(\frac{40}{143} \times100\)
= 27.98% = 28%
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