Chemistry - Mole Concept Question with Solution | TestHub

ChemistryMole ConceptAtomic mass/Average Atomic Mass/Average Molecular MassMedium2 minQB

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Passage / Comprehension

For a hypothetical chemical reaction represented by $3 A (g) ⟶ C (g) + D (g)$ , the following informations are known. Information

(i) At $t = 0$ , only 1 mole of A is present, and the gas has V.D. = 60.

(ii) At $t = 30$ min, the gaseous mixture consists of all three gases and has a vapor density = 75.

(iii) The molecular mass of C = 200.

Calculate:

The ratio of molar masses of A and D is

Answer:

Solution:

Initial V.D. = 60 $\Rightarrow$ Molar mass of A = $2 \times 60 = 120 g m o l^{- 1}$ .

Using conservation of mass: $3 A \to C + D$ , so $3 M_{A} = M_{C} + M_{D}$ .

Given $M_{C} = 200 g m o l^{- 1}$ and $M_{A} = 120 g m o l^{- 1}$ .

Therefore, $3 (120) = 200 + M_{D} \Rightarrow M_{D} = 160 g m o l^{- 1}$ .

Hence, $M_{A} : M_{D} = 120 : 160 = 3 : 4$ .

Stream:JEESubject:ChemistryTopic:Mole ConceptSubtopic:Atomic mass/Average Atomic Mass/Average Molecular Mass

⏱ 2mℹ️ Source: QB

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