Question

100 mL of a solution contains 2 g of acetic acid and 3 g of sodium acetate providing $K_a=1.8\times {10}^{-5}$. Choose the correct option.

• A. This solution is basic in nature
• B. This solution is acidic in nature
• C. This solution is amphoteric in nature
• D. This solution is neutral in nature

Answer 1

Answer: (B)

This solution is acidic in nature

Ka of acetic acid $=1.8\times {10}^{-5}$

$pKa=-log(1.8\times {10}^{-5})=4.74$

According to Henderson Hasselbalch equation,

$pH=-log{K}_a+log\frac{\left[Salt\right]}{\left[Base\right]}$

$\left[Salt\right]=\frac{3\times 1000}{82\times 100}mol{L}^{-1}$

$\left[Acid\right]\frac{2\times 1000}{60\times 100}mol{L}^{-1}$

$pH=-log1.8\times {10}^{-5}+log\frac{\frac{3\times 1000}{82\times 100}}{\frac{2\times 1000}{60\times 100}}$

$pH=4.7851$

Therefore, this solution is acidic in nature.