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What is the empirical formula of a compound containing 40.00% carbon, 6.67% hydrogen, and 53.33%...

Chemistry
JAMB 2023

What is the empirical formula of a compound containing 40.00% carbon, 6.67% hydrogen, and 53.33% oxygen by mass?

  • A. C\(_4\)H\(_8\)O\(_4\)
  • B. CH\(_2\)O
  • C. C\(_2\)H\(_4\)O\(_2\)
  • D. C\(_3\)H\(_6\)O\(_3\)
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Correct Answer: Option B
Explanation

To determine the empirical formula, we first need to convert the percentages to moles by assuming a convenient mass for the sample. Let's assume we have 100 grams of the compound.

Mass of carbon = 40.00 grams
Mass of hydrogen = 6.67 grams
Mass of oxygen = 53.33 grams

Now, we calculate the moles of each element:
Moles of carbon = 40.00 g / molar mass of carbon = 40.00 g / 12.01 g/mol ≈ 3.33 mol
Moles of hydrogen = 6.67 g / molar mass of hydrogen = 6.67 g / 1.01 g/mol ≈ 6.60 mol
Moles of oxygen = 53.33 g / molar mass of oxygen = 53.33 g / 16.00 g/mol ≈ 3.33 mol

Now, we find the smallest whole-number ratio of the moles:
C ≈ 3.33 / 3.33 ≈ 1
H ≈ 6.60 / 3.33 ≈ 2
O ≈ 3.33 / 3.33 ≈ 1

Thus, the empirical formula is CH2O.

There is an explanation video available below.


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Explanation Video

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