Unit 6 Stoichiometry Study Guide

Name:____________________ Per:______
Unit 9 Outline- Thermodynamics, Reaction Rates, & Chemical Equilibrium
Chapters 17 & 18
Essential Skills/ State Standards:
9-1. Describe how temperature and heat flow in terms of the motion of molecules (or atoms). (CSS: 7a)
9-2. Know that chemical processes & phase changes can either release energy (exothermic) or absorb energy (endothermic). (CSS:
7b, 7c)
9-3. Solve problems involving heat flow and temperature changes, using known values of specific heat (q= m ●c ● Δ T) & latent
heat of phase change (q= m Δ H). (CSS: 7d)
9-4. Know the rate of reaction is the decrease in concentration of reactants or the increase in concentration of products with time &
depends on such factors as: concentration, temperature, and pressure. (CSS: 8a, 8b)
9-5. Know the definition and role of activation energy & catalyst in a chemical reaction. (CSS: 8d*, 8c)
9-6. Know how to use Le Chatelier’s principle to predict the effect of changes in concentration, temperature, and pressure (CSS:
9a)
9-7. Know that equilibrium is established when the forward and reverse reaction rates are equal. (CSS: 9b)
Vocabulary
Condensation
Freezing
Vaporization
Melting
Boiling
Sublimation
Deposition
Heat
Temperature
Thermochemistry
Exothermic
Endothermic
Calorimeter
Heat of reaction
Joule
Le Chatlier’s
Specific heat
principle
q= m ●c ● Δ T
Equilibrium
q= m Δ H Activation Energy
vaporization
q= m Δ H Catalyst
fusion
Book Assignments:
Topic Read Required Problems
1. Heat, Temperature & Specific Heat Section 17-1 p. 511-524 Section 17-p. 524 #2, 5 & 6
Chapter 17 Review p. 548 #16 & 17
3. Chemical Equilibrium & Le Chatelier’s Principle Section 12-3 p. 372-375
Section 18-2 p. 562-568
Chapter 18 Review p. 586 #4, 6 & 7
4. Phase Changes Diagrams & Latent Heat of
Phase Change
Section 12-3 p. 378-382 Section 12-3 p. 382 #4-8
Chapter 12 Review p. 389 #19, 28, 31 & 37
5. Collision Theory & Activation Energy Section 17-3 p. 532-534 Section 17-3 p. 537 #2, 3 & 5
6. Reaction Rates & Catalysts Section 17-4 p. 538-544 Section 17-4 p. 545 #2-4
Study Guide (Use notes, worksheets, and labs in addition to this study guide)
1. According to the collision theory, what 3 things must happen in order for two molecules to react?
2. What is the importance of the activation energy in a chemical reaction?
3. Using the collision theory, explain if the following would increase/ decrease the rate of reaction:
2 HCl(aq) + Mg(s) MgCl 2 (aq) + H 2 (g)
a. Increase temp: b. Increase HCl c. Increase pressure d. Remove MgCl 2 e. Add H 2
4. Identify the following terms with their correct number/letter from the graphs:
* Reactants- * Products-
* Activation energy (number/letter & amount in Joules)-
* Is this reaction exothermic or endothermic?
5. Explain how a catalyst affects the activation energy in a chemical
reaction. (Also, show on the above graph what a catalyst might
do).

6. Explain what is wrong with the following statement: “When chemical equilibrium exists, the concentration
of the reactants and products remain constant and the forward and reverse reactions cease.”
7. According to Le Chatelier’s principle, how does a system at equilibrium respond to stress?
8. Use the Le Chatelier’s principle to predict how the system at equilibrium would shift to relieve stress:
I. CO (g) + 3 H 2 (g) CH 4 (g) + H 2 O (g) + 113 J
Stresses: a. adding CO b. Removing water c. Adding pressure d. Adding heat
II. H 2 O(l) + heat H 2 O(g)
Stresses: a. add pressure b. remove heat c. add H 2 O(l)
9. Determine if the process is endothermic or exothermic in each of the following & why:
a) hot pack (pack’s point of view) b) cold pack (pack’s point of view)
c) H 2 + O 2 H 2 O + 483.6 kJ (heat) d) H 2 O + 483.6 kJ (heat) H 2 + O 2
10. Label: a) the phase change names b) temperatures at which the phase Δ occurs
c) endothermic or exothermic d) Amount of heat required for each phase change
H 2 O (Solid) H 2 O (Liquid) H 2 O (Gas)
11. a) What does temperature measure? b) Why can we use °C in this unit (vs. K)?
12. a) What does heat measure? b) How is heat calculated & with what units?
13. What are the 2 different things an object can do with heat energy when it’s absorbed?
14. How can there be heat added/ removed during a phase change, yet there is no change in temperature?
15. Water has a very high specific heat. What does that tell you about water?
16. You are going to build a slide at a playground and your two option for materials are : Aluminum (specific heat =
0.897 J/ g º C) or Iron (specific heat 0.449 J/ g º C). Based on their specific heat, which would you chose &
why?
17. Identify all the variables in the following equations & when you would use each equation:
a. q= m ●c ● Δ T b. q= m Δ H vaporization c. q= m Δ H fusion
18. Ammonia (∆ H Vap = 1371 J/g) & alcohol (∆ H Vap for alcohol = 841 J/g) are left out in an open container.
Which of these liquids would turn into a gas faster? Why?
19. If it takes 41.72 joules to heat a piece of gold weighing 18.69 g from 10 °C to 27 °C, what is the specific heat
of gold?
20. How many joules of heat are needed to change 30.0 grams of steam at 105 °C down to a liquid at 45 °C?
Make a graph to indicate this change.