The work done during combustion of `9 xx 10^(-2)` kg of ethane, `C_(2)H_(6)(g)` at 300 K is (Given R=8.314 J `deg^(-1) mol^(-1)`, atomic mass C = 12, H=1)

Options

A. 6.236 J
B. 6.236 kJ
C. 18.71 kJ
D. -18.71 kJ

Answer

C

Explanation

Work done in chemical reaction is
`W=- Delta n_(g) RT`
`IC_(2)H_(6(g))+(7)/(2)O_(2(g)) rarr 2CO_(2(g)) +3H_(2)O_((l))`
`Delta n =2-4.5 =-2.5`
`W=+2.5xx8.314xx300=6.2355 kJ`
For 30 g=1 mole =6.2355 kJ
`therefore` For 90 g=3 moles =18.71 kJ