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Mole concept and Stoichiometry — Chemistry STD 10 — Question

ICSE BoardEnglish MediumSTD 10ChemistryMole concept and Stoichiometry3 Marks
Question
An organic compound, whose vapour density is $45,$ has the following percentage composition $H =2.22 \%, O =71.19 \%$ and remaining carbon. Calculate,
(a) its empirical formula, and
(b) its molecular formula
✓

Answer

Element $\%$ at. mass atomic ratio simple ratio
$ \text { C } 26.5912 \frac{26.59}{12}=2.21_1$
$\text { H } 2.221 \frac{2.22}{1}=2.22 $
O $71.1916 \frac{71.19}{16}=4.44_2$
(a) its empirical formula $= CHO _2$
(b) empirical formula mass $=45$
Vapour density $=45$
So, molecular mass $=$ V.D $\times 2=90$
so, molecular formula $= C _2 H _2 O _4$

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