Question

$0.76g$ of silver salt of dibasic organic acid on ignition left $0.463g$of metallic silver. The equivalent mass of acid is:
Option:
A $70$
B $108$
C $60$
D $50$

Answer 1

Hint: Equivalent mass is the common term in chemistry which is defined as molar mass of an element divided by n-factor. Equivalent mass has got unit of mass. This was determined by experiments before but now by using molar masses we can find out equivalent masses.

Complete answer:
Firstly, we need to calculate equivalent mass of silver salt of organic acid
To find that we can use the basic information which is given in the question that is mass of silver salt and mass of silver residue.
Now, we all know that the chemical equivalent for silver is $108$.
So, the equivalent mass of silver salt of organic acid
$ = \dfrac{{Mass{\text{ of silver salt}}}}{
  Mass{\text{ of silver residue}} \\
  {\text{ = }}\dfrac{{0.76}}{{0.463}} \times 108 \\
   = 177g \\
 } \times 108$
Now, equivalent mass of acid$ = $
Equivalent mass of silver salt $ - $equivalent mass of silver $ + $equivalent mass of hydrogen
$
   = 177 - 108 + 1 \\
   = 70 \\
 $
 Hence, the equivalent mass of acid is equal to $70$

So, The correct option is A.

Note:
Equivalent mass and atomic mass are two different things. Atomic mass is the sum of number of protons and neutrons present in an atom of an element whereas equivalent mass is the mass of given substance which then gets combined with quantity of another substance which has fox value.