Question

Calculate the pH of a buffer solution when 32.0 mL of a 0.25 M H2CO3 is mixed with 20.0 mL of a 0.15 M NaHCO3​

Answer 1

pH of buffer solution : 4.32

Further explanation

A buffer solution is a solution that can maintain a good pH value due to the addition of a little acid or a little base or dilution.

The buffer solution can be acidic or basic

Acid buffer solutions consist of weak acids(H₂CO₃) and their salts.(NaHCO₃)

mol H₂CO₃

$\tt 0.032\times 0.25=0.008$

mol NaHCO₃

$\tt 0.02\times 0.15=0.003$

$\tt [H^+]=Ka\dfrac{mole~weak~acid}{mole~salt}\\\\(H^+]=1.8\times 10^{-5}\dfrac{0.008}{0.003}=4.8\times 10^{-5}\\\\pH=5-log~4.8=4.32$