Respuesta :
Answer:
The answer is -791.5 kJ (option c)
Explanation:
You know:
SO₂ (g) → S (s) + O₂ (g) ΔH°rxn = +296.8 kJ
2 SO₂ (g) + O₂ (g) → 2 SO₃ (g) ΔH°rxn = -197.8 kJ
You must add them to obtain the desired equation:
2 S(s) + 3 O₂(g) → 2 SO₃(g) ΔH°rxn = ?
You want to calculate the ∆H (heat of reaction) of the combustion reaction, that is, the heat that accompanies the entire reaction. The calculation is made using Hess's law. This law states: when the reactants are converted to products, the enthalpy change is the same, regardless of whether the reaction is carried out in one step or in a series of steps.
In Hess's law he explains that the enthalpy changes are additive, ΔHneta = ΣΔHr and contains three rules:
- If the chemical equation is inverted, the ΔH symbol is inverted as well.
- If the coefficients are multiplied, multiply ΔH by the same factor.
- If the coefficients are divided, divide ΔH by the same divisor.
The sum of the fitted equations should give the problem equation. In this case:
2*( S(s) + O₂(g) → SO₂ ) To obtain the desired reaction, this equation must be inverted, so the enthalpy value is also inverted. It must also be multiplied by 2, then the whole equation is multiplied, both reactants and products and the value of the enthalpy. So ΔH°rxn = (-296.8 kJ)*2= -593.6 kJ
2 SO₂(g) + O₂(g) → 2 SO₃ (g) ΔH°rxn = -197.8 kJ
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2 S(s) + 3 O₂(g) → 2 SO₃(g) ΔH°rxn = -791.4 kJ ( Enthalpies are added algebraically)
The answer is -791.5 kJ (option c)
The value of ΔH°rxn for the 2S(s) + 3O₂(g) → 2SO₃(g) is -791.4 kJ.
What is enthalpy?
Enthalpy of the reaction tells about the amount of heat released or absorbed during any chemical reaction.
Given that,
2SO₂(g) + O₂(g) → 2SO₃(g) ΔH°rxn = -197.8 kJ
SO₂(g) → S(s) + O₂(g) ΔH°rxn = 296.8 kJ
To obtain the required reaction first we have to invert the second equation and multiply that by 2 and then add with the left hand side as well as the right hand side of the reaction, we get:
2S(s) + 3O₂(g) → 2SO₃(g)
ΔH°rxn of the reaction will be calculated as-
ΔH°rxn = -2(296.8 kJ) + (-197.8 kJ)
ΔH°rxn = -791.4 kJ
Hence, option (C) is correct i.e. -791.4 kJ.
To know more about enthalpy of reaction, visit the below link:
https://brainly.com/question/27072962
