Two elements A and B which form 0.15 moles of A2B and AB3 type compounds. If both A2B and AB3 weigh equally, then the atomic weight of A is _____________ times of atomic weight of B.
Answer (integer)
2
Solution
<p>Let atomic weight of A = x</p>
<p>and atomic weight of B = y</p>
<p>$\therefore$ Molar mass of A<sub>2</sub>B = 2x + y</p>
<p>and molar mass of AB<sub>3</sub> = x + 3y</p>
<p>Now, weight of 0.15 moles of A<sub>2</sub>B = (2x + y) 0.15</p>
<p>and weight of 0.15 moles of AB<sub>3</sub> = (x + 3y) 0.15</p>
<p>Given, weight of 0.15 moles of A<sub>2</sub>B and AB<sub>3</sub> are equal.</p>
<p>$\therefore$ (2x + y)0.15 = (x + 3y)0.15</p>
<p>$\Rightarrow$ x = 2y</p>
<p>$\Rightarrow {x \over y} = 2$</p>
<p>$\therefore$ Atomic weight of A is 2 times of atomic weight of B.</p>
About this question
Subject: Chemistry · Chapter: Some Basic Concepts of Chemistry · Topic: Mole Concept
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