Question

Explain methods for determination of equivalent weight​

Answer 1

$\huge {\orange {\bf {\underline {\underline {AnSwer}}}:-}}$

Methods for determination of the equivalent weight are

⟶ Hydrogen displacement method :-

This method is used for those elements which can evolve hydrogenfrom acids, i.e., active metals.

equivalent weight of metal =

$\sf \frac{weight \:of \: metal }{weight \: of \: h_{2} \: gas \: (displaced)} \times 1.008$

⟶ Oxide formation method :-

A known mass of the element is changed into Chloride directly or indirectly. The mass of Chloride is noted.

Mass of oxygen = (Mass of oxide - Mass of element)

equivalent weight of element =

$\sf \frac{weight \: of \: element}{weight \: of \: oxygen} \times 8$

⟶ Chloride formation method :-

A known mass of the element is changed into chloride directly or indirectly. The mass ofthe chloride is determined

equivalent weight of element =

$\sf \frac{weight \: of \: element}{weight \: of \: chlorine} \times 35.5$

⟶ Metal to metal displacement method

More active metal can displace less active metal from its salt solution. The mass of the displaced metal bear the same ratio as their equivalent weights.

$\sf \frac{ m_{1} }{m_{2}} = \frac{E_{1}}{E_{2}}$

⟶ Double decomposition method :-

This method is based on the following points :-

• The mass of the compound reacted and the mass of product formed are in the ratio of their equivalent masses .
• The equivalent mass of the compound (electrovalent) is the sum of equivalent masses of its radicals.
• The equivalent mass of a radical is equal to the formula mass of the radical divided by its charge.

AB + CD → AD(ppt.) + CB

$\sf \frac{mass \: of \: AB}{mass \: of \: AD} = \frac{equivalent \: mass \: of \: AB}{equivalent \: mass \: of \: AD}$

$= \sf \frac{equivalent \: mass \: of \: A \: + equivalent \: mass \: of \:B}{equivalent \: mass \: of \:A \: + equivalent \: mass \: of \:D}$

⟶ Silver salt method :-

This method is used for finding the equivalent weight of carbonic (organic) acids. A known mass of the RCOOAg is changed into Ag through combustion.

The mass ofAg is determined.

$\sf \frac{equivalent \: weight \: of \: RCOOAg}{equivalent \: weight \: of \: Ag} = \frac{weight \: of \: RCOOAg}{weight \: of \: Ag}$

$\sf equivalent \: weight \: of \: RCOOAg = \frac{weight \: of \: RCOOAg}{weight \: of \: Ag} \times 108$