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WorksheetsGibbs Free Energy
Total questions: 16
Worksheet time: 16mins
What does Gibbs Free Energy tell us?
How much energy is given off by a reaction.
The tendency of a reaction to become "random"
How spontaneous a reaction is.
What information do we need to perform a calculation of Gibbs Free Energy?
Enthalpy of the reaction.
Entropy of the reaction.
The temperature of the reaction in Kelvin.
All of the above are needed.
Which of the following would most likely lead to a spontaneous reaction.
A high negative enthalpy.
A low negative enthalpy.
A high positive enthalpy.
A low positive enthalpy.
Your enthalpy is +20 and your entropy is +5. Which temperature will give a spontaneous reaction?
0
4
8
Your enthalpy is high and negative but your entropy is also negative. What type of temperature would you want to get a spontaneous reaction?
low
high
Your enthalpy is positive and your entropy is positive. What type of temperature would you want to ensure a spontaneous reaction.
very high
very low
Which combination of ΔH and ΔS NEVER has a spontaneous reaction?
+ΔH and +ΔS
+ΔH and -ΔS
-ΔH and -ΔS
-ΔH and +ΔS
Your enthalpy is -20 and your entropy is -8. Which temperature will give you a spontaneous reaction?
1
3
5
6. The formation ½ A2 + 2 B2 + C --> CAB4 has an enthalpy of formation of -104 kJ and a change in entropy of -60.8 J/K at 30 °C. What is the free energy and spontaneity of the reaction?
-85.6 kJ, spontaneous
-18.3 kJ, not spontaneous
+18.3 kJ, spontaneous
+85.6 kJ, not spontaneous
For the process at 250C : I2(g) →I2(s). What are the signs for ΔG, ΔH and ΔS?
ΔG + ΔH - ΔS -
ΔG - ΔH - ΔS -
ΔG - ΔH + ΔS +
ΔG - ΔH + ΔS +
Predict the signs of ΔH , ΔS and ΔG for the reaction:
Mg(s) --> Mg(g)
Δ H = - , Δ S = + and Δ G = - (all temperature)
Δ H = + , Δ S = + and Δ G = - (At all temperature)
Δ H = + , Δ S = + and Δ G = - (At low temperature)
Δ H = + , Δ S = + and Δ G = - (At high temperature)
At what temperature would a given reaction become spontaneous if ΔH =+119kJ and ΔS=+263J/K.mol
452 K
2210 K
382 K
363 K
1. Given the following information, calculate ΔG0 for the reaction below at 250C: (K = 0C + 273)
SnCl4(l) + 2 H20(l) → SnO2(S) + 4HCl(g),
ΔH0=133.0 kJ and ΔS0 =401.5 J/K
-252.6 kJ
-13.4 kJ
13.4 kJ
252.6 kJ
