Question

Blood plasma has the following composition (milliequivalents per litre). Calculate its osmotic pressure at ${37}^{\circ }C$.
$N{a}^{+}=138,C{a}^{2+}=5.2,K^{+}=4.5,$
$M{g}^{2+}=2.0,C{l}^{-}=105,HC{O}_3^{-}=25,$
$P{O}_4^{3-}=2.2,S{O}_4^{2-}=0.5,$
Proteins = 16, others = 1.0

• A. $7.47\text{atm}$
• B. $7.30\text{atm}$
• C. $7.29\text{atm}$
• D. $7.40\text{atm}$

Answer 1

The correct option is A $7.47\text{atm}$

Given
$millimoles$ = $\frac{milliequivalents}{charge}$

$N{a}^{+}=\frac{138}{1}=138$

$C{a}^{2+}=\frac{5.2}{2}=2.6$

$K^{+}=\frac{4.5}{1}=4.5$

$M{g}^{2+}=\frac{2}{2}=1$

$C{l}^{-}=\frac{105}{1}=105$

$HC{O}_3^{-}=\frac{25}{1}=25$

$P{O}_4^{3-}=\frac{2.2}{3}=0.73$

$S{O}_4^{2-}=\frac{0.5}{2}=0.25$

Protein= 16
others = 1

Total $minnimoles/litre$ = 294.08
Total $moles/litre$ = 0.29418

$\pi =C\times R\times T$
= $0.294\times 0.0821\times 310$
= 7.48 $atm$