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The percentage of water of crystallization in ZnSO\(_4\).7H\(_2\)O is? [Zn = 65, S = 32,...

Chemistry
JAMB 2009

The percentage of water of crystallization in ZnSO\(_4\).7H\(_2\)O is?
[Zn = 65, S = 32, O = 16, H = 1]

  • A. 33%
  • B. 44%
  • C. 55%
  • D. 87%
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Correct Answer: Option B
Explanation

molar mass of water [7H\(_2\)O] = 7[ 2 * 1 + 16] → 7 * 18 = 126g/mol

molar mass of ZnSO\(_4\).7H\(_2\)O = [65 * 1] + [32 * 1] + [16 * 4] + 7[ 2 * 1 + 16] 

→ 65 + 32 + 64 + 126 = 287g/mol

percentage of water of crystallization = \(\frac{mass of water of crystallization}{mass of hydrated compound} * 100%\)

→ \(\frac{126}{287} * 100\) = 43.9

≈ 44%

There is an explanation video available below.


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Explanation Video

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WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
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WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
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