1. Tardigrade
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  3. Chemistry
  4. The pH of blood stream is maintained by a proper balance of H2CO3 and NaHCO3 concentrations. What volume of 5 M NaHCO3 solution should be mixed with a 10 mL sample of blood which is 2 M in H2CO3, in order to maintain a pH of 7.4? ( Ka for H2CO3 in blood is 738 × 10-7)

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Q. The pH of blood stream is maintained by a proper balance of $ H_2CO_3 $ and $NaHCO_3$ concentrations. What volume of $5 \,M \,NaHCO_3$ solution should be mixed with a $10 \,mL$ sample of blood which is $2 \,M$ in $ H_2CO_3$, in order to maintain a pH of $7.4$? ( $K_a$ for $H_2CO_3$ in blood is $ 738 \times 10^{-7})$

IIT JEEIIT JEE 1993Equilibrium

Solution:

Mixing $ H_2CO_3 $ with $ NaHCO_3 $ results in buffer solution.
$pH= pK_ a + log \frac{ [ NaHCO_3 ]}{ [ H_2CO_3 ]} = pK_a + log \frac{ n \, ( NaHCO_3) }{ n \, ( H_2CO_3 ) } $
$\Rightarrow 7.4 = - log (7.8 \times 10^{ - 7 } ) + log \, \frac{ x }{ 20} $
$\Rightarrow x = 400 \,mmol $
$ NaHCO_3 = 5 \times V \Rightarrow V = 80\, mL$