Ba thí dụ về phản ứng tỏa nhiệt \(\left( {\Delta H < 0} \right)\):
\(\eqalign{ & {C_{\left( r \right)}} + {O_{2\left( k \right)}}\,\, \to \,\,C{O_{2\left( k \right)}};\cr&\Delta H = - 393,5\,\,KJ/mol \cr & {\rm{CuS}}{O_{4\,\left( {dd} \right)}} + Z{n_{\left( r \right)}}\,\, \to \,\,ZnS{O_{4\,\,\left( {dd} \right)}} + C{u_{\left( r \right)}};\cr&\Delta H = - 231,04\,\,KJ/mol \cr & H{I_{\left( k \right)\,}}\,\, \to {1 \over 2}{H_{2\,\left( k \right)}} + {1 \over 2}{I_{2\,\left( k \right)}};\cr&\Delta H = - 25,9\,\,KJ/mol \cr} \)
Ba thí dụ về phản ứng thu nhiệt \(\left( {\Delta H > 0} \right):\)
\(\eqalign{ & {C_{\left( r \right)}} + {H_2}{O_k}\,\, \to \,\,C{O_{\left( k \right)}} + {H_{2\,\left( k \right)}};\cr&\Delta H = + 131,25\,\,KJ/mol \cr & {1 \over 2}{H_{2\,\left( k \right)}} + {1 \over 2}{I_{2\,\left( k \right)}}\,\, \to \,\,H{I_{\left( k \right)}};\cr&\Delta H = + 25,9\,\,KJ/mol \cr & CaC{O_{3\,\left( r \right)}}\,\, \to \,\,Ca{O_{\left( r \right)}} + C{O_{2\,\left( k \right)}};\cr&\Delta H = + 177,9\,KJ/mol \cr} \)
