CH 16

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This deck includes 28 flashcards covering thermochemical equation, enthalpy change, entropy change, and related concepts. Use it to review key Chemistry ideas, focus on weak cards, and prepare for your exam with StudyLess.

• 01

  CH 16 Study Guide 2

  CH 16.2 · Thermodynamics: Entropy and Gibbs Free Energy

• 02

  CH 16.1 Study Guide 1

  CH 16.1 · Basic Concepts of Thermochemistry

1. 01

   What do coefficients in a balanced thermochemical equation represent?

   Numbers of moles of reactants and products, and they can be fractions.

2. 02

   Why must the physical state be included in a thermochemical equation?

   It is an important factor.

3. 03

   How is the change in enthalpy related to the number of moles in a thermochemical equation?

   Directly proportional to the number of moles of substances undergoing a change.

4. 04

   How does changing temperature influence the value of the enthalpy change (∆H)?

   Usually not significantly influenced by changing temperature.

5. 05

   What is Heat?

   Energy transferred between samples of matter because of a difference in temperature.

6. 06

   What is Hess's Law?

   The overall enthalpy change in a reaction is equal to the sum of enthalpy changes for individual steps.

7. 07

   What is Molar Enthalpy of Formation (∆H_f)?

   Enthalpy change when one mole of compound forms from its elements in standard state.

8. 08

   What is Enthalpy of Reaction?

   Quantity of energy transferred as heat during a chemical reaction.

9. 09

   What is Enthalpy Change?

   Amount of energy absorbed by a system as heat during a process at constant pressure.

10. 10

    What is Enthalpy of Combustion (∆H_c)?

    Enthalpy change during the combustion of one mole of a substance in presence of oxygen.

11. 11

    What is Temperature?

    Measure of average kinetic energy of the particles in a sample of matter.

12. 12

    What is Specific Heat?

    Amount of energy required to raise the temperature of 1g of substance by 1°C.

13. 13

    What is the Formula for Energy Lost or Gained?

    q = Cp * m * ΔT

14. 14

    What is an Exothermic Reaction?

    A reaction that releases heat.

15. 15

    What is an Endothermic Reaction?

    A reaction that absorbs heat.

16. 16

    What is a Thermochemical Equation?

    An equation that includes the amount of energy released or absorbed as heat.

17. 17

    What processes increase entropy?

    Decomposition, dissolving, melting, combustion, boiling/vaporization, sublimation.

18. 18

    What is the formula for Entropy Change (ΔS)?

    ΔS = ΣS products - ΣS reactants.

19. 19

    What results from ΔS > 0?

    Entropy increased.

20. 20

    What results from ΔS < 0?

    Entropy decreased.

21. 21

    What is the formula for Gibbs Free Energy Change (ΔG)?

    ΔG = ΔH – TΔS.

22. 22

    What condition of ΔG indicates a spontaneous reaction?

    If ΔG < 0, the reaction is spontaneous.

23. 23

    When ΔH > 0 and ΔS < 0, what is the spontaneity of the reaction?

    ΔG > 0 (reaction is never spontaneous).

24. 24

    When ΔH < 0 and ΔS > 0, what is the spontaneity of the reaction?

    ΔG < 0 (reaction is spontaneous).

25. 25

    When ΔH < 0 and ΔS < 0, what is the spontaneity of the reaction?

    Depends—ΔG < 0 at low temperature.

26. 26

    When ΔH > 0 and ΔS > 0, what is the spontaneity of the reaction?

    Depends—ΔG < 0 at high temperature.

27. 27

    What is Enthropy?

    Measure of degree of randomness of particles.

28. 28

    What is Entropy Change (ΔS)?

    The difference in entropy of a system during a reaction or state change.