To determine the percentage composition of oxygen, we first find the mass of carbon and hydrogen produced from the combustion. Mass of C in CO₂: Molar mass of CO₂ = 12.01 + 2(16.00) = 44.01 g/mol Mass

Question

To determine the percentage composition of oxygen, we first find the mass of carbon and hydrogen produced from the combustion.

Mass of C in CO₂:

Molar mass of CO₂ = 12.01 + 2(16.00) = 44.01 g/mol

Mass of C = $(0.7938 g C O_{2}) \times \frac{12.01 g C}{44.01 g C O _{2}} = 0.2165 g C$

Mass of H in H₂O:

Molar mass of H₂O = 2(1.008) + 16.00 = 18.016 g/mol

Mass of H = $(0.4428 g H_{2} O) \times \frac{2 \times 1.008 g H}{18.016 g H _{2} O} = 0.0495 g H$

Mass of O in the organic compound:

Mass of O = Total mass of compound - Mass of C - Mass of H

Mass of O = $0.492 g - 0.2165 g - 0.0495 g = 0.226 g$

Percentage of O in the compound:

$% O = \frac{M a ss o f O}{T o t a l ma ss o f co m p o u n d} \times 100$

$% O = \frac{0.226 g}{0.492 g} \times 100 = 45.93%$

Rounded to the nearest whole number, the percentage composition of oxygen is 46%.

TestHub · Accepted Answer

0.492 g of C x ​ H y ​ O z ​ Gives 0.7938 g CO 2 ​ = 0.018 moles 0.4428 g H 2 ​ O = 0.0246 moles So moles of C = 0.018 ⇒ 0.216 g Moles of H = 0.049 ⇒ 0.049 g ∴ wt. of Oxygen = 0.492 − 0.216 − 0.049 = 0.227 g % of Oxygen = 0.492 0.227 ​ × 10046 (approx.)

Chemistry - Mole Concept Question with Solution | TestHub

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