Using the following information and the fact that the average c―h bond enthalpy is 414 kj/mol, estimate the standard enthalpy of formation of methane (ch4). c(s) → c(g) δh o rxn = 716 kj/mol 2h2(g) → 4h(g) δh o rxn = 872.8 kj/mol

The standard enthalpy of formation of methane is -67.2 kJ/mol.

Explanation:

...[1]

...[2]

...[3]

Since, the bond formation is taking place energy will release that id reaction will be an exothermic reaction

...[4]

Using Hess's law:

[4] = [1] + [2] + [3]

The standard enthalpy of formation of methane is -67.2 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