Name: Law of Multiple Proportions
Uploaded: 2019-07-19
Duration: 6 min 43 s
Description: The Law of multiple proportions is applicable only when two elements combine to form two or more compounds. Watch this video to know how this law is applicable.

Question

Define equivalent weight. How will you determine the equivalent weight of zinc by hydrogen displacement method?

0.325 g

of a metal when dissolved in

dil . H_{2} {SO}_{4}

liberated

0.01 g

of hydrogen. What is the equivalent weight of the metal?

Accepted Answer

The equivalent mass of an element is a number which expresses how many parts by mass of the element combines with or displaces from compound $1.008$ parts by mass of hydrogen or $8$ parts by mass of oxygen or $35.45$ parts by mass of chlorine.

One equivalent of any substance reacts with one equivalent of the other substance to produce one equivalent of each of the products. Thus, it is evident that all substances combine or appear on the basis of an equivalence. The equivalent mass or equivalent weight expressed in gram is called gram-equivalent mass or gram-equivalent weight.

Many metals such as zinc, magnesium, aluminium etc, react with acid liberating hydrogen gas. Now, one mole of hydrogen gas occupies $22.4$ litres at $NTP$ , and weighs $2.016 g$ . Hence, $11.2$ litres of hydrogen gas at $NTP$ would weigh $1.008 g$ . Therefore, in the displacement method, that mass of the metal in grams which would liberate $11.2$ litres of hydrogen at $NTP$ would be the gram equivalent mass of the metal.

Hydrogen displacement method:

Metals such as zinc, magnesium, aluminium, iron, tin etc, displace hydrogen gas from dilute acids. A known amount of the metal is allowed to react with dilute acid and the volume of evolved hydrogen gas, measured under atmospheric pressure and at room temperature, is converted to the volume at $NTP$ . It has been mentioned earlier that the gram-equivalent mass of a metal is that weight of the metal in grams which would liberate $11.2$ litres of hydrogen gas at $NTP$ .

Given,

Weight of the metal $= 0.325 g$ .

Weight of liberated hydrogen $= 0.01 g$ .

$0.01 g$ of hydrogen is equivalent to $0.325 g$ of the metal.

Therefore, $1.008 g$ of hydrogen will be equivalent to $\frac{0.325}{0.01} \times 1.008 = 32.76 g$ of the metal.

Hence, the equivalent weight of the metal is $32.76 g$ .

Define equivalent weight. How will you determine the equivalent weight of zinc by hydrogen displacement method? $0.325 g$ of a metal when dissolved in $dil . H_{2} {SO}_{4}$ liberated $0.01 g$ of hydrogen. What is the equivalent weight of the metal?

Important Questions on Basic Concepts Atoms & Molecules

Learn and Prepare for any exam you want !

Define equivalent weight. How will you determine the equivalent weight of zinc by hydrogen displacement method? 0.325 g of a metal when dissolved in dil. H2SO4 liberated 0.01 g of hydrogen. What is the equivalent weight of the metal?

Important Questions on Basic Concepts Atoms & Molecules

Learn and Prepare for any exam you want !

Define equivalent weight. How will you determine the equivalent weight of zinc by hydrogen displacement method? $0.325 g$ of a metal when dissolved in $dil . H_{2} {SO}_{4}$ liberated $0.01 g$ of hydrogen. What is the equivalent weight of the metal?