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WorksheetsPractice Hess's Law
Total questions: 10
Worksheet time: 20mins
Using the equations below:
C(s) + O2(g) → CO2(g) ∆H = –390 kJ
Mn(s) + O2(g) → MnO2(s) ∆H = –520 kJ
what is ∆H (in kJ) for the following reaction?
MnO2(s) + C(s) → Mn(s) + CO2(g)
910
130
-130
-910
Using the equations below
Cu(s) + 1/2O2(g) → CuO(s) ∆H = –156 kJ
2Cu(s) + O2(g) → Cu2O(s) ∆H = –170 kJ
what is the value of ∆H (in kJ) for the following reaction?
2CuO(s) → Cu2O(s) + 1/2O2(g)
142
15
-15
-142
Consider the following equations.
Mg(s) + O2(g) → MgO(s) ∆H = –602 kJ
H2(g) + O2(g) → H2O(g) ∆H = –242 kJ
What is the ∆H value (in kJ) for the following reaction?
MgO(s) + H2(g) → Mg(s) + H2O(g)
-844
-360
+360
+844
The following equations show the oxidation of carbon and carbon monoxide to carbon dioxide.
C(s) +O2(g) → CO2(g) ΔH = –x kJ mol–1
CO(g) + O2(g) → CO2(g) ΔH = –y kJ mol–1
What is the enthalpy change, in kJ mol–1, for the oxidation of carbon to carbon monoxide?
C(s) + O2(g) → CO(g)
x + y
-x - y
y - x
x - y
Hess' Law makes use of which principle to calculate the enthalpy change of a reaction?
The law of conservation of energy
The law of conservation of matter
The law that you will always find a lost item in the last place you look for it
Murphy's law
For Hess' Law to be used what must be the same for all of the reactions being studied?
The initial conditions of pressure and temperature.
The final conditions of pressure and temperature.
The initial and the final conditions of pressure and temperature.
The initial and the final conditions of pressure and temperature, and the number of moles of reactants.
Which of the following statements are true for the reaction:
SO2(g) + 1/2O2(g) ↔ SO3(g) ΔH = –92 kJ mol-1
Where ↔ indicates that the reaction can proceed in the forward and the reverse direction.
The forward and reverse reaction both produce 92 kJ of energy.
Oxidising 2 moles of SO2 would produce twice as much energy.
The reverse reaction has an enthalpy of +92 kJ mol-1.
Collecting the SO3 produced in the liquid state would not change the measured enthalpy.
In order to find the enthalpy of combustion of C3H8 how must the enthalpy changes be arranged?
ΔH3 = ΔH1 + ΔH2
ΔH2 = ΔH3 - ΔH1
ΔH1 = ΔH2 - ΔH3
0 = ΔH1 + ΔH2 + ΔH3
The standard enthalpy change of formation values of two oxides of phosphorus are:
P4(s) + 3O2(g) → P4O6(s) ΔHf = –1600 kJ mol–1
P4(s) + 5O2(g) → P4O10(s) ΔHf = –3000 kJ mol–1
What is the enthalpy change, in kJ mol–1, for the reaction below?
P4O6(s) + 2O2(g) → P4O10(s)
+4600
+1400
–1400
–4600
Standard conditions are defined as...
298K and 1.00 x 105 kPa
273K and 1.00 x 105 kPa
