Calculate enthalpy of the reaction ethene+hydrogen gives ethane are -1410KJ,-286kJ and -1560KJ respectively at 25°c
dH rxn = (n*dHo products) - (n*dHo reactants).
To calculate the enthalpy of the reaction "ethene + hydrogen gives ethane," we need to apply the Hess's Law of Constant Heat Summation. According to Hess's Law, the enthalpy change of a reaction is independent of the reaction pathway and depends only on the initial and final states of the reaction.
Step 1: Write out the balanced chemical equation for the reaction:
C2H4 + H2 → C2H6
Step 2: Assign enthalpy values to the reactions given:
ΔH1 = -1410 kJ (enthalpy of the reaction: C2H4 → C2H6)
ΔH2 = -286 kJ (enthalpy of the reaction: H2 → H2)
ΔH3 = -1560 kJ (enthalpy of the reaction: C2H4 + H2 → C2H6)
Note: The enthalpy values are given for the specific reactions, so we don't need to convert them.
Step 3: Apply the Hess's Law equation:
ΔH3 = ΔH1 + ΔH2
Step 4: Substitute the given values into the equation:
-1560 kJ = -1410 kJ + ΔH2
Step 5: Solve for ΔH2:
ΔH2 = -1560 kJ - (-1410 kJ)
ΔH2 = -1560 kJ + 1410 kJ
ΔH2 = -150 kJ
Therefore, the enthalpy change for the reaction "ethene + hydrogen gives ethane" is -150 kJ at 25°C.