Answer:
DH = +90kJ
The reaction is endothermic.
Explanation:
Hess law states that regardless of the multiple steps a reaction takes, the total enthalpy of the reaction is the sum of all the multiple steps taken.
C(s) + 2H2O(g) → CO2(g) + 2H2(g) ΔH= ?
CO2(g) → C(s) +O2(g) ΔH = -393.5 KJ 2H2O(g) → 2H2(g) + O2(g) ΔH = -483.6 KJ
DH = DHproduct- DHreactant
= -393.5kJ -(-483.6kJ)
= 90.1kJ
Overall reaction equation:
C(s) + O2(g) + 2H2O(g) --> CO2(g) + 2H2(g) + O2(g)
The reaction is endothermic because the value of the total enthalpy is positive therefore no heat is lost to the surroundings.
Attached below is the hess law chart drawn for better understanding.
Answer:
The heat of formation is 90.1 KJ and the reaction is endothermic.
Explanation:
Chemical equations can be treated as algebraic equations and their enthalpy of reaction can be added or subtracted according to the operation applied. In the given problem, we have to determine the heat of formation of hydrogen gas using the given two equations. which are
CO₂(g) → C(s) +O₂(g) ΔH₁ = 393.5 KJ --------------------------------------- (1)
2H₂O(g) → 2H₂(g) + O₂(g) ΔH₂ = 483.6 KJ --------------------------------------- (2)
It can be seen from the above equation that by inversing the first equation (its enthalpy of reaction becomes negative) and adding equation 2 with it we obtain the desired equation, this is shown below
C(s) + O₂(g) → CO₂(g) ΔH₃ = -393.5 KJ ------------------------------------ (3)
2H₂O(g) → 2H₂(g) + O₂(g) ΔH₂ = 483.6 KJ --------------------------------------(2)
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C(s) + 2H₂O(g) → CO₂(g) + 2H₂(g)
The heat of formation of this equation can be calculated from equation 3 and 2, mathematically expressed as,
ΔH = ΔH₃ + ΔH₂
ΔH = -393.5 KJ + 483.6 KJ
ΔH = 90.1 KJ
The heat of formation is positive, hence the reaction is endothermic.
