Some Basic Principles Of Organic Chemistry Question 138
Question: If 0.228 g of silver salt of dibasic acid gave a residue of 0.162g of silver on ignition then molecular weight of the acid is [AIIMS 2000]
Options:
A) 70
B) 80
C) 90
D) 100
Show Answer
Answer:
Correct Answer: C
Solution:
Mass of silver salt taken = 0.228 gm Mass of silver left = 0.162 gm Basicity of acid = 2 Step 1- To calculate the equivalent mass of the silver salt $ \frac{Eq\text{.}massofsilversalt}{Eq\text{.}massofsilver}=\frac{MassofAcidtaken}{Massofsilverleft} $
$ =\frac{E}{108}=\frac{0.228}{0.162} $
$ =E=\frac{0.228}{0.162}\times 108=152,(Eq\text{.}massofsilver\text{salt)} $ Step 2 - To calculate the eq.
mass of acid.
Eq.
mass of acid = Eq.
mass of silver salt - Eq.
mass of Ag + Basicity = 152 - 108 + 1 = 152 - 109 = 43 (Eq.
mass of acid) Step 3- To determine the molecular mass of acid.
Mol.
mass of the acid = Eq.
mass of acid ´ basicity = 45 ´ 2 = 90.
