Question

calculate the percentage of sulphur in SO2 and in SO3.

Answer 1

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$molecular \: mass \: of \: so_2 = 32 + 2 \times 16 \\ \\ = 32 + 32 \\ \\ = 64u$

Percentage of Sulphur in SO2
$= ( \frac{mass \: of \: sulphur}{mass \: of \: compound} \times 100)\% \\ \\ = ( \frac{32}{68} \times 100)\% \\ \\ = 50\%$


Next,

$molecular \: mass \: of \: so_3 = 32 + 3 \times 16 \\ \\ = 32 + 48 \\ \\ = 80u$


Percentage of Sulphur in SO3

$= ( \frac{mass \: of \: sulphur}{mass \: of \: compound} \times 100)\% \\ \\ = ( \frac{32}{80} \times 100)\% \\ \\ = 40\%$


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