Ethyne (c2 h2 (g), mc032-1.jpghf = 226.77 kj/mol) undergoes complete combustion in the presence of oxygen to produce carbon dioxide (co2 (g), mc032-2.jpghf = –393.5 kj/mol ) and water (h2 o(g), mc032-3.jpghf = –241.82 kj/mol) according to the equation below.

mc032-4.jpg

what is the enthalpy of combustion (per mole) of c2 h2 (g)?
–2511.2 kj/mol
–1255.6 kj/mol
–862.1 kj/mol
–431.0 kj/mol

when the volume of gas is   changed from   717.73 ml   to 852 ml   the temperature will   change   from 315   c to 452   c

    calculation

this is calculated using the charles law formula

that is,   v1/t1 = v2/t2

          v1=?

        t1 = 315 c   into   kelvin = 315 +273 = 588 k

        v2 = 852   ml

        t2 = 425c + 273 =698 k

make v1   the subject of the formula ( by   multiplying both side by t1)

  v1=( v2 xt1) / t2

v1= (852 ml   x 588 k)/ 698 k= 717.73 ml