Free Printable Entropy, Enthalpy and Gibbs Free Energy

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Entropy, Enthalpy and Gibbs Free Energy

Total questions: 20

Worksheet time: 28mins

Name

Class

Date

Which phase of matter has the greatest motion and least orderly arrangement?

solid

liquid

gas

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

Which one of the following is always positive when a spontaneous process occurs?

ΔH univ

ΔH surr

ΔS surr

ΔS univ

ΔS sys

ΔS will be positive for the reaction

2H2 (g) + O2 (g) -> 2H2O (g)

2NO2 (g) -> N2O4 (g)

BaF2 (s) ->Ba2+ (aq) + 2F- (aq)

2Hg (l) + O2 (g) ->2HgO (s)

A reaction that is not spontaneous at low temperature can become spontaneous at high temperature if ΔH is __________ and ΔS is __________.

+, +

-, -

+, -

-, +

+, 0

Which of these have a DECREASE in entropy?

CaCO₃(s) → CaO(s) + CO₂(g)

2NO₂(g) → N₂O₄(g)

2NH₃(g) → 3H₂(g) + N₂(g)

C₆H₆(l) → C₆H₆(g)

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

Given the change of phase:

CO₂(g) —> CO₂(s)

As CO₂(g) changes to CO₂(s), the entropy of the system

decreases

increases

remains the same

Entropy increases from solid, liquid to gas. Why?

Molecular disorder increases

Molecular randomness decreases

Molecules are more energetic

Molecules are more reactive

10.

Reactions tend to be spontaneous if they are exothermic.

True

False

11.

1. 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

12.

For which of these processes is the value of ΔH expected to be negative?

1. The temperature increases when calcium chloride dissolves in water.

2. Steam condenses to liquid water

3. Water boils

4. Dry ice sublimates

1 and 2 only

3 and 4 only

2 and 3 only

1 only

13.

The equation that relates enthalpy, temperature and entropy is

Hess's Law

Second Law of Thermodynamics

Gibbs Free Energy

Calorimetry

14.

Solid magnesium dissolves in a solution of hydrochloric acid, releasing hydrogen gas and heat from a solution of magnesium chloride. What is the sign on ΔG for this reaction?

Negative because it is spontaneous

Negative because it is nonspontaneous

Positive because it is spontaneous

Positive because it is nonspontaneous

15.

ΔH value in an endothermic reaction is a positive number.

True

False

16.

Temperature is a measure of average _________ energy of individual atoms.

heat

potential

mechanical

kinetic

17.

The __________ law of thermodynamics states that entropy is always increasing.

first

second

third

zeroth

18.

Which of the following conditions leads to a reaction that is always spontaneous?

ΔH > 0 , ΔS >0

ΔH < 0 , ΔS > 0

ΔH < 0 , ΔS < 0

ΔH > 0 , ΔS < 0

19.

Spontaneous reactions may be extremely slow.

True

False

20.

Entropy is a measure of the number of possible ways that the energy of a system can be distributed.

true

false

100 %

Entropy, Enthalpy and Gibbs Free Energy

Total questions: 20

Worksheet time: 28mins

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