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
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)
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