Question

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Q. At 37$°$C, the osmotic pressure of blood is 7.65 atm. How much glucose (Mol. wt. = 180) should be used per litre for an intervenous injection that is to have same osmotic pressure (isotonic) as blood?

Answer 1

Dear Student,

$$\begin{gathered} \mathrm{We}\mathrm{know}\mathrm{that}, \\ \mathrm{\pi V}=\mathrm{nRT} \\ \mathrm{or},\mathrm{n}=\frac{\mathrm{\pi V}}{\mathrm{RT}} \\ \mathrm{or},\mathrm{n}=\frac{(7.65\mathrm{atm})(1\mathrm{L})}{(0.0821{\mathrm{Latmmol}}^{-1}{\mathrm{K}}^{-1})(310\mathrm{K})} \\ =0.301\mathrm{mol} \\ \mathrm{Now},\mathrm{Moles}=\frac{\mathrm{Mass}}{\mathrm{Molecular}\mathrm{mass}} \\ \mathrm{So},\mathrm{Mass}\mathrm{of}\mathrm{glucose}=0.301\mathrm{mol}\times 180{\mathrm{gmol}}^{-1}=54.2\mathrm{g} \end{gathered}$$