Question

Calculate the dH value for the following chemical reaction:C + 2H2O CO2 + 2H2First equation: C + O2 CO2 dH = -394 kJSecond Equation: 2H2 + O2 2H2O dH = -484 kJ

Answer 1

Answer:

dH = +90kJ

Explanations:

Given the following chemical reactions with their individual enthalpy change expressed as:

$\begin{gathered} C+O_2\rightarrow CO_2\text{ }\triangle H=-394kJ \\ 2H_2+O_2\rightarrow2H_2O\text{ }\triangle H=-484kJ \end{gathered}$

We need the enthalpy change value for the reaction shown:

$2H_2O\rightarrow CO_2+2H_2$

To get the equivalent reaction from the 2chemical reactions above, we will interchange the product and reactant of the formation of water to have:

$\begin{gathered} C+\cancel{O_2}\operatorname{\rightarrow}CO_2\operatorname{\triangle}H=-394kJ \\ 2H_2O\rightarrow2H_2+\cancel{O_2}\triangle H=+484kJ \\ _{--------------------------------------} \\ C+2H_2O\rightarrow CO_2+2H_2\text{ }\triangle H=-396kJ+484kJ=+90kJ \end{gathered}$

Hence the dH value for the following chemical reaction C + 2H2O -> CO2 + 2H2 is +90kJ