Question

A gas occupies 300ml at 27 degree and 730mm of Hg pressure. What would be its volume at STP?

Answer 1

Dear student

The STP conditions are Standard Temperature and Pressure conditions.

Since only the physical conditions are changed and there is no chemical reaction taking place, so the number of moles of the gas will remain the same.

Thus equating the number of gaseous moles at both the conditions, one gets

$$\begin{gathered} \frac{\mathrm{P}1\times \mathrm{V}1}{\mathrm{R}\times \mathrm{T}1}=\frac{\mathrm{P}2\times \mathrm{V}2}{\mathrm{R}\times \mathrm{T}2} \\ \mathrm{Taking}1\mathrm{as}\mathrm{the}\mathrm{given}\mathrm{conditions}\mathrm{and}\mathrm{the}2\mathrm{as}\mathrm{the}\mathrm{STP}\mathrm{conditions}\mathrm{where}\mathrm{T}=273\mathrm{K}\mathrm{and}\mathrm{P}=1\mathrm{atm}=760\mathrm{mm}\mathrm{Hg} \\ \frac{730\mathrm{mm}\mathrm{Hg}\times 300\mathrm{mL}}{300\mathrm{K}}=\frac{760\mathrm{mm}\mathrm{Hg}\times \mathrm{V}}{273\mathrm{K}} \\ \mathrm{V}=262.22\mathrm{mL} \\ \mathrm{Regards} \end{gathered}$$