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Worksheetsgibb free energy❤️
Total questions: 19
Worksheet time: 49mins
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 high positive enthalpy.
A low negative enthalpy.
A low positive enthalpy.
What are the best conditions to lead towards a spontaneous reaction?
high negative enthalpy, high temp, high negative entropy
high positive enthalpy, high temp, high negative entropy
high negative enthalpy, low temp, high positive entropy
high negative enthalpy, high temp, high positive entropy.
Entropy increases from solid, liquid to gas. Why?
Molecules are more energetic
Molecular randomness decreases
Molecular disorder increases
Molecules are more reactive
Which sample has the lowest entropy?
1 mole of KNO3(l)
1 mole of H2O(l)
1 mole of KNO3(s)
1 mole of H2O(g)
Which phase change represents a decrease in entropy?
gas to liquid
solid to liquid
liquid to gas
solid to gas
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?
-18.3 kJ, not spontaneous
+85.6 kJ, not spontaneous
-85.6 kJ, spontaneous
+18.3 kJ, spontaneous
Predict the signs of ΔH , ΔS and ΔG for the reaction:
Mg(s) --> Mg(g)
Δ H = + , Δ S = + and Δ G = - (At high temperature)
Δ H = + , Δ S = + and Δ G = - (At all temperature)
Δ H = - , Δ S = + and Δ G = - (all temperature)
Δ
Δ H = + , Δ S = + and Δ G = - (At low temperature)
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
Which reaction has the greatest increase in entropy of the system?
A. HCl (g) + NH3 (g) → NH4Cl (s)
B. (NH4)2Cr2O7 (s) → Cr2O3 (s) + N2 (g) + 4H2O (g)
C. CaCO3 (s) → CaO (s) + CO2 (g)
D. I2 (g) → I2 (s)
A
B
C
D
Choose the correct correlation between Gibbs free energy and feasibility.
a reaction to be feasible, ΔG has to be negative.
a r
a reaction to be feasible, ΔG has to be zero
a reaction to be feasible, ΔG has to be positive.
o
no correlation between ΔG and feasibility
At what temperature would a given reaction become spontaneous if ΔH =+119kJ and ΔS=+263J/K.mol
382 K
2210 K
452 K
363 K
1. Calculate the standard entropy change for the following reaction: Cu(s)+1/2 O2(g) → CuO(s). Given that
S0 (Cu(s)) = 33.15 J/K*mol
S0 (O2(g)) = 205.14 J/K*mol
S0 (CuO(s)) = 42.5 J/K*mol
195.66 J/K.mol
-93.09 J/K.mol
93.09 J/K.mol
+195.66 J/K.mol
Given the following information, calculate ΔG0 for the reaction below at 250C:
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
If a process is exothermic and not spontaneous, then what must be true?
ΔH > 0
ΔS > 0
ΔG = 0
ΔS < 0
In which of the following reactions do you expect to have a decrease in entropy?
2Fe(s) +3/2O2(g)→Fe2O3(s)
Fe(s) →Fe(l)
H2O2(l) →2H2O(l) +O2(g)
HF(l) →HF(g)
At what temperature would a given reaction become spontaneous if ΔH =+119kJ and ΔS=+263J/K.mol
2210 K
382 K
452 K
363 K
What is the standard entropy change for this reaction in K/k/mol
-284
+284
+96
-96
