Question

What is the equivalent weight of NaCl?
a.) 58.5
b.) 48
c.) 48.5
d.) 16.6

Answer 1

Hint: Equivalent weight is basically the amount of a substance which can combine with or displace a fixed amount of some other substance.

Complete step-by-step answer:
Equivalent weight is obtained by dividing molecular weight by the valence of the element.
Mathematically, \[{\text{Equivalent weight = }}\dfrac{{{\text{molecular mass}}}}{{{\text{valance of the element}}}}\]
Molecular mass of NaCl is – (22.98 amu of Na + 35.45 amu for Cl) = 58.44
Since only one hydrogen atom could bond with NaCl hence the valence is 1.
So equivalent weight of NaCl is \[ = {\text{ }}\dfrac{{58.44}}{1}{\text{ }} \approx {\text{ 58}}{\text{.5}}\]
Hence, option A is correct.

Additional information: The units and dimensions of equivalent weight are the same as that of mass. In case of acid-base reactions, the mass which provides or reacts with one mole of hydrogen cations \[{\text{(}}{{\text{H}}^ + })\] is called as equivalent weight of that particular acid/base. It can also be calculated by dividing the molecular weight by the number of positive or negative ions that are produced as a result of dissolution of the compound. Similarly, in oxidising and reducing agents, equivalent weight is determined by dividing the gram molecular weight by the number electrons lost or gained in a reaction.
Resins which undergo crosslinking reactions, have particular types of functional groups. The value of equivalent weight here, is the mass of a polymer which has one equivalent of reactivity.

Note: Equivalent weight of the substance has importance in gravimetric analysis and volumetric analysis. With change in type of reaction, the equivalent weight of the same substance might change.