Question

Which of the following has highest equivalent weight? Given: At.wt \(H=1,\ C=12,\ O=16,\ S=32,\ Na=23,\ Ca=40\)

• A. Sulphuric acid
• B. Sodium carbonate
• C. Sodium sulphate
• D. Calcium carbonate

Hint:

Compare equivalent weights by calculating \(\frac{\text{molecular weight}}{n\text{-factor}}\) for each compound.

Answer 1

The Correct Option is C

Concept: Equivalent weight is: \[ \text{Equivalent weight}=\frac{\text{Molecular weight}}{n\text{-factor}} \]

Step 1: For sulphuric acid: \[ H_2SO_4 \] Molecular weight: \[ 2+32+64=98 \] \(n=2\), so: \[ \text{Eq. wt.}=\frac{98}{2}=49 \]

Step 2: For sodium carbonate: \[ Na_2CO_3 \] Molecular weight: \[ 46+12+48=106 \] \(n=2\), so: \[ \text{Eq. wt.}=\frac{106}{2}=53 \]

Step 3: For sodium sulphate: \[ Na_2SO_4 \] Molecular weight: \[ 46+32+64=142 \] \(n=2\), so: \[ \text{Eq. wt.}=\frac{142}{2}=71 \]

Step 4: For calcium carbonate: \[ CaCO_3 \] Molecular weight: \[ 40+12+48=100 \] \(n=2\), so: \[ \text{Eq. wt.}=\frac{100}{2}=50 \]

Step 5: Highest equivalent weight is: \[ 71 \] Therefore, \[ \boxed{\text{Sodium sulphate}} \]