The standard enthalpies of formation of C O 2 ( g ) , H 2 O l and glucose (s) at 2 5 o C are - 400 kJ / mol , - 300 kJ / mol and - 1300 kJ / mol , respectively. The standard enthalpy combustion per gram of glucose at 2 5 o C is ( Δ H f 0 = − 1300   k J   m o l −   f o r   glucose )

Step-by-step solution

Heat of combustion : It is the amount of heat evolved or absorbed (i.e. change in enthalpy) when one mole of the substance is completely burnt in air or oxygen. Standard enthalpy of combustion of glucose reaction is given as ​ C 6 H 1 2 O 6 s + 6 O 2 g → 6 CO 2 g + 6 H 2 O l Δ H C o = Σ Product Δ H f o - Σ Reactant Δ H f o = 6 - 4 0 0 + 6 - 3 0 0 Product - - 1 3 0 0 × 1 + 6 × 0 Reactant = - 2 4 0 0 - 1 8 0 0 + 1 3 0 0 = - 2900 kJ mole -1 Molecular mass of glucose = 7 2 + 1 2