Delta H reaction for the following reaction: C(s)+H2O(g)=>CO(g)+H2(g)
To find the ΔH reaction (also known as the enthalpy change of the reaction) for the given reaction, you can use Hess's Law or the bond energy approach.
Hess's Law states that the overall enthalpy change in a chemical reaction is the same regardless of the reaction's steps. You can use this law to calculate the enthalpy change of a reaction by adding or subtracting the enthalpy changes of other known reactions.
Alternatively, you can use the bond energy approach, which involves summing up the bond energies of the reactants and subtracting the bond energies of the products. The difference in bond energy will give you the enthalpy change of the reaction.
To use Hess's Law, you need to find known reactions with enthalpy changes that can be combined to obtain the desired reaction. Let's break down the given reaction into smaller steps:
1. C(s) + O2(g) → CO2(g) ΔH1
2. H2(g) + 1/2 O2(g) → H2O(g) ΔH2
Notice that these two reactions, when combined, give the desired reaction:
C(s) + H2O(g) → CO(g) + H2(g)
Now, you can find the ΔH reaction by combining the enthalpy changes of these two reactions:
ΔH reaction = ΔH1 + ΔH2
To find the enthalpy changes (ΔH1 and ΔH2), you can refer to the standard enthalpy of formation (∆Hf°) values of each compound involved. The ∆Hf° values represent the enthalpy change when one mole of a compound is formed from its elements under standard conditions.
Here are the standard enthalpy of formation values (in kJ/mol):
∆Hf°(CO2) = -393.5 kJ/mol
∆Hf°(H2O) = -241.8 kJ/mol
∆Hf°(CO) = -110.5 kJ/mol
∆Hf°(H2) = 0 kJ/mol
Using these values, you can calculate the enthalpy changes for each step:
ΔH1 = ∆Hf°(CO2) - ∆Hf°(C) - ∆Hf°(O2)
ΔH2 = ∆Hf°(H2O) - ∆Hf°(H2) - 1/2 * ∆Hf°(O2)
Once you have the values of ΔH1 and ΔH2, you can add them together to find ΔH reaction.
Keep in mind that the units of ∆Hf° and ΔH reaction will be in kJ/mol.
If you want delta Hf it is
DHfrxn = (DHfproducts) - (DHfreactants)
Look up the values for delta Hf in your text or notes.