Calculate the change in heat for the reaction 2C + H2 > C2H2 given the following chemical equations and their respective enthalpy changes

Question

i) C2H2 + 5/2Og >>>>>2CO2 + H2O enthalpy change = 1299.6kg/mol
ii) 2C + 2O2 >>>>> 2CO2 enthalpy change = -787.0kg/mol
iii) H2 + 1/2 O2 >>>>>>>>> H2O enthalpy change = -285.8kg/mol

Answer 1

The change in heat for the reaction 2C + H2 > C2H2 can be calculated by adding the enthalpy changes of the given chemical equations.

2C + 2O2 > 2CO2: -787.0 kJ/mol
H2 + 1/2 O2 > H2O: -285.8 kJ/mol
C2H2 + 5/2 O2 > 2CO2 + H2O: 1299.6 kJ/mol

Now, we need to rearrange the equations to match the given reaction:

2CO2 + H2O > C2H2 + 5/2 O2: -1299.6 kJ/mol

Since the enthalpy change is for the reaction as written in the given equation, we need to flip the sign for the enthalpy change:

C2H2 + 5/2 O2 > 2CO2 + H2O: -(-1299.6) kJ/mol = 1299.6 kJ/mol

Now, let's sum up the enthalpy changes for the given equations:

-787.0 kJ/mol + (-285.8 kJ/mol) + 1299.6 kJ/mol = 226.8 kJ/mol

Therefore, the change in heat for the reaction 2C + H2 > C2H2 is 226.8 kJ/mol.