\( = - 368.2 - ( - 210.8) = - 157.4\)
\(\Delta {H_c}({C_3}{H_8}) - \Delta {H_c}({C_2}{H_6})\)
\( = - 526.2 - ( - 368.4) = - 157.8\)
Thus, average
\(\Delta {H_c}( - C{H_2}) = \frac{{157.4 + 157.8}}{2}\)
\( = - 157.6\,k\,cal\,mo{l^{ - 1}}\)
Then,
\(\Delta {H_c}({C_6}{H_{14}}) = \Delta {H_c}({C_3}{H_8}) + 3\Delta {H_c}( - C{H_2})\)
\( = - 526.2 + 3( - 157.6) = - 999\,k\,cal\,mo{l^{ - 1}}\)