Question

A compound having empirical formula X2Y is made of two elements X and Y. Find it’s molecular formula if the atomic weight of X is 10 and that of Y is 5 and the compound has a vapour density 25.

August 5, 2024

Answer

The empirical formula is X₂Y

Empirical formula weight = 2(10) + 5 = 25

Vapour density (V.D.) = 25

Molecular weight = 2 × V.D. = 2 × 25 = 50

$Molecular\ weight\over Empirical\ formula\ weight$

$50\over 25 = 2$

∴ Molecular formula = [X₂Y]₂ = X₄Y₂

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