Use the standard enthalpies of formation for the reactants and products to solve for the ΔHrxn for the following reaction. (The ΔHf of C2H4 is 52.26 kJ/mol, CO2 is -393.509 kJ/mol, and H2O is -241.818 kJ.)
C2H4 (g) + 3O2(g) 2CO2 (g) + 2H2O(g)
ΔHrxn =
The reaction is .
To solve for the ΔHrxn (standard enthalpy change for the reaction), you need to use the enthalpies of formation for the reactants and products. The enthalpy of formation represents the change in enthalpy when one mole of a substance is formed from its elements in their standard states.
1. Identify the standard enthalpies of formation for each compound involved in the reaction:
- ΔHf of C2H4 (ethene) = 52.26 kJ/mol
- ΔHf of CO2 (carbon dioxide) = -393.509 kJ/mol
- ΔHf of H2O (water) = -241.818 kJ/mol
2. Write down the balanced chemical equation for the reaction:
C2H4 (g) + 3O2 (g) -> 2CO2 (g) + 2H2O (g)
3. Calculate the ΔHrxn using the formula:
ΔHrxn = Σ(ΔHf of products) - Σ(ΔHf of reactants)
- Σ(ΔHf of products) = 2 * (ΔHf of CO2) + 2 * (ΔHf of H2O)
- Σ(ΔHf of reactants) = (ΔHf of C2H4) + 3 * (ΔHf of O2)
Substitute the values:
ΔHrxn = 2 * (-393.509 kJ/mol) + 2 * (-241.818 kJ/mol) - (52.26 kJ/mol) - 3 * 0 kJ/mol
4. Perform the calculations:
ΔHrxn = -787.018 kJ/mol - 484.936 kJ/mol - 52.26 kJ/mol
ΔHrxn = -1324.214 kJ/mol
Therefore, the ΔHrxn for the given reaction is -1324.214 kJ/mol.
To solve for the ΔHrxn for the given reaction, we need to use the standard enthalpies of formation for each compound involved in the reaction.
The standard enthalpy of formation (ΔHf) is the change in enthalpy when one mole of a compound is formed from its elements in their standard states.
Using the standard enthalpies of formation given, we can calculate ΔHrxn by following these steps:
Step 1: Identify the compounds involved in the reaction and their stoichiometric coefficients.
- C2H4 (g) has a coefficient of 1
- O2 (g) has a coefficient of 3
- CO2 (g) has a coefficient of 2
- H2O (g) has a coefficient of 2
Step 2: Determine the change in enthalpy for each compound using the standard enthalpies of formation.
ΔHrxn = (2 * ΔHf(CO2)) + (2 * ΔHf(H2O)) - (ΔHf(C2H4)) - (3 * ΔHf(O2))
Step 3: Substitute the given values into the formula.
ΔHrxn = (2 * -393.509 kJ/mol) + (2 * -241.818 kJ/mol) - (52.26 kJ/mol) - (3 * 0 kJ/mol)
Step 4: Simplify the equation.
ΔHrxn = -787.018 kJ/mol + (-483.636 kJ/mol) - 52.26 kJ/mol
ΔHrxn = -1322.914 kJ/mol
Therefore, the ΔHrxn for the given reaction is -1322.914 kJ/mol.