$KC{l_{\left( s \right)}} + 20{H_2}O \to KCl\,\left( {20\,{H_2}O} \right);\Delta H = + 15.90\,kJ$
$KC{l_{\left( s \right)}} + 200{H_2}O \to KCl\,\left( {200\,{H_2}O} \right);\Delta H = + 18.58\,kJ$
$2CO_{(g)} + O_{2{(g)}}$ $\rightarrow$ $2CO_{2{(g)}}$
$CH _{4}+2 O _{2} \rightarrow CO _{2}+2 H _{2} O (\Delta H =-891 kJ / mol)$