Question

How many grams of NaHCO₃ would have to be added to 2.00 L of 0.100 M H₂CO₃ to yield a solution with a pH = 6.00? (K_a = 4.2x10^-7

Answer 1

Solution:

$pH=pK_a+log\dfrac{[HCO_2^-]}{[H_2CO_3]}$

$6=6.38+log\dfrac{[HCO_3^-]}{0.1}$

$[HCO_3^-]=0.042\;M$

$m=0.042\;M*2L*84.01(\frac{g}{mole})=7.06\;g\;of\;NaHCO_3$

Answer:

7.06 grams of NaHCO₃ should be added.