Question

A gaseous mixture of propane and butane of volume $3$ litre on complete combustion produces $11.0$ litre $C{O}_2$ under standard conditions of temperature and pressure. The ratio of volume of butane to propane is?

• A. $1:2$
• B. $2:1$
• C. $3:2$
• D. $3:1$

Answer 1

The correct option is B $2:1$

Suppose , the volume of propane = $VL$
$\therefore C_3{H}_8\left(g\right)+5O_2\left(g\right)\to 3C{O}_2\left(g\right)+4H_{2}O\left(l\right)$
$V$ $5V$ $3V$
$C_4{H}_{10}\left(g\right)+\frac{13}{2}{O}_2\left(g\right)\to 4C{O}_2\left(g\right)+5H_{2}O\left(l\right)$
$(3-V)$ $\frac{13}{2}(3-V)$ $4(3-V)$
$\because$ Total volume of $C{O}_2$ produced $=10L$;
$\because 3V+4(3-V)=11$ ; $\therefore V=1$
$\therefore$ Volume of butane $=(3-1)=2L$
Thus , the ratio of volume of butane to propane $=2:1$