Use Hess's Law to find ΔH for the following reactions: Express your answers in kJ/mol of the first reactant on the left in each equation
1. NH3(g) + O2(g) = N2(g) + H2O(g)
2.NO(g) + O2(g) = NO2(g)
3. H2SO4(I) = SO2(g) + H2O(g) + O2(g)
4. Mg(s) + CO2(g) = MgO(s) + C(s)
5. F2(g) + H2O(I) = HF(g) + O2(g)
6. C6H6(l) + O2(g) = CO2(g) + H2O(g)
7. NH3(g) + O2(g) = NO2(g)+H2O(g)
8. CH4(g) + O2(g) = CO2(g) + H2O(l)
9. H2S(g) + O2(g) = H2O(l) + SO2(g)
10 CaO(s) + H2O(l) = Ca (OH)2(s)
To find ΔH for each reaction using Hess's Law, we need to find a series of reactions whose sum is equal to the desired reaction. We can manipulate the given reactions to achieve this.
1. NH3(g) + O2(g) = N2(g) + H2O(g)
Given reaction.
2. NO(g) + O2(g) = NO2(g)
Given reaction.
3. H2SO4(I) = SO2(g) + H2O(g) + O2(g)
We can rearrange this equation to match the desired reaction by multiplying it by a factor of 2:
2H2SO4(I) = 2SO2(g) + 2H2O(g) + O2(g)
4. Mg(s) + CO2(g) = MgO(s) + C(s)
Given reaction.
5. F2(g) + H2O(I) = HF(g) + O2(g)
We can multiply the given reaction by 2 to obtain the desired reaction:
2F2(g) + 2H2O(I) = 2HF(g) + O2(g)
6. C6H6(l) + O2(g) = CO2(g) + H2O(g)
Given reaction.
7. NH3(g) + O2(g) = NO2(g)+H2O(g)
Given reaction.
8. CH4(g) + O2(g) = CO2(g) + H2O(l)
We need to modify this equation to match the desired reaction by changing the state of water:
CH4(g) + 2O2(g) = CO2(g) + 2H2O(g)
9. H2S(g) + O2(g) = H2O(l) + SO2(g)
We can change this equation to match the desired reaction by doubling it:
2H2S(g) + 4O2(g) = 2H2O(l) + 2SO2(g)
10. CaO(s) + H2O(l) = Ca (OH)2(s)
Given reaction.
Now, we can combine the equations to find ΔH for each reaction:
1. NH3(g) + O2(g) = N2(g) + H2O(g)
ΔH = -ΔH3 + ΔH2 + ΔH1
2. NO(g) + O2(g) = NO2(g)
ΔH = ΔH2
3. H2SO4(I) = SO2(g) + H2O(g) + O2(g)
ΔH = 0.5(ΔH3)
4. Mg(s) + CO2(g) = MgO(s) + C(s)
ΔH = ΔH4
5. F2(g) + H2O(I) = HF(g) + O2(g)
ΔH = 2(ΔH5)
6. C6H6(l) + O2(g) = CO2(g) + H2O(g)
ΔH = ΔH6
7. NH3(g) + O2(g) = NO2(g)+H2O(g)
ΔH = ΔH7
8. CH4(g) + O2(g) = CO2(g) + H2O(l)
ΔH = ΔH8
9. H2S(g) + O2(g) = H2O(l) + SO2(g)
ΔH = 2(ΔH9)
10 CaO(s) + H2O(l) = Ca (OH)2(s)
ΔH = ΔH10
To find ΔH using Hess's Law, it is necessary to use known enthalpy changes for other reactions and manipulate them to obtain the desired reaction.
Hess's Law states that the overall enthalpy change of a reaction is equal to the sum of the enthalpy changes of individual reactions, as long as the reactants and products are the same.
Here's how you can use Hess's Law to find ΔH for each given reaction:
1. NH3(g) + O2(g) = N2(g) + H2O(g):
- Since the reaction is already balanced, no manipulation is required.
- Look for known reaction enthalpies for the given species involved in the reaction from a reliable source or data table.
- Use the corresponding enthalpies to balance the equation, ensuring that the reactants and products match the given reaction.
- Determine ΔH for the reaction by summing up the enthalpies of the manipulated reactions.
2. NO(g) + O2(g) = NO2(g):
- Observe that the desired equation involves the reactants and products of the given equation.
- Reverse the given equation (multiply by -1) to match the desired equation.
- Note the change in sign for the enthalpy value.
- Determine ΔH for the reaction by summing up the enthalpies of the manipulated reactions.
Repeat steps 1-2 for the remaining equations, applying the appropriate manipulations and sign changes as required.
Remember, it is essential to find reliable and accurate values for the enthalpies of the individual reactions involved in the manipulation process. Consult reputable sources or data tables to obtain these values.
To find ΔH for these reactions using Hess's Law, you need to break down each reaction into intermediate steps with known ΔH values. Then you can use the law of conservation of energy to add or subtract the ΔH values to find the overall ΔH for the reaction. Here are the steps for each reaction:
1. NH3(g) + O2(g) = N2(g) + H2O(g)
- Given reaction
2. NO(g) + O2(g) = NO2(g)
- Given reaction
3. H2SO4(I) = SO2(g) + H2O(g) + O2(g)
- Given reaction
4. Mg(s) + CO2(g) = MgO(s) + C(s)
- Given reaction
5. F2(g) + H2O(I) = HF(g) + O2(g)
- Given reaction
6. C6H6(l) + O2(g) = CO2(g) + H2O(g)
- Given reaction
7. NH3(g) + O2(g) = NO2(g) + H2O(g)
- Given reaction
8. CH4(g) + O2(g) = CO2(g) + H2O(l)
- Given reaction
9. H2S(g) + O2(g) = H2O(l) + SO2(g)
- Given reaction
10. CaO(s) + H2O(l) = Ca (OH)2(s)
- Given reaction
Unfortunately, I cannot provide the specific stepwise calculations for each reaction as the provided reactions do not have known ΔH values for intermediate steps. You will need to refer to a reliable source or database for the ΔH values of individual reactions to solve these problems using Hess's Law.