Introduction to Chemistry formative exercise answers about molecular compounds

Chemical Reactions: Energy Changes, Reaction Rates, Equilibrium, LeChatelier's Principle

These questions are a quick overview of the topics in this lesson. You are not expected to know this material before hand. The questions are intended to help you focus on material in the lesson. After you have studied the lesson you should be able to answer these and even more complicated questions.

1. T
Energy is needed to break covalent bonds.

2. T
Energy is released when a covalent bond is formed.

3. F
All covalent bonds are the same strength.

4. T
Compounds with weak bonds react quickly.

5. F
The heat of reaction is always positive for an exothermic reaction.

6. T
The Law of Conservation of energy says the energy in the universe is constant.

7. F
A spontaneous reaction is one that produces an explosion

8. T
Entropy, S, increases when disorder increases.

9. T
Free energy is the energy available from a reaction that can be used for other purposes.

10. T
Activation energies are high for slow reactions.

11. F
Reactions occur more slowly if the temperature is raised.

12. F
A reaction with an activation energy of 350,000 calories is fast.

13. T
The reaction is most likely exothermic CHCH + H₂ ---> CH₃CH₃

14. T
Entropy is always increasing. It is not governed by a conservation law.

15. T
Reaction rates increase when the concentration of reactants increases

16. T
Catalysts increase reaction rates and are not consumed in the reaction.

17. T
Reactions at equilibrium have a constant ratio of reactants to products.

18. T
An equlibrium system can be altered by changing the temperature of the system.

19. T
The equilibrium expression for the equation C₂H₂ + 2 H₂ --> CH₃CH₃has H₂ in the bottom.

20. T
The rate of a reaction depends on the way molecules contact one another in collisions.

21. T
Enthapy change is the fancy word for energy transfer under constant pressure.

22. T
The Greek symbol delta, D , is used to represent "change".

23. F
The equilibrium constant for a reaction indicates the speed of the reaction.

24. F
When K = 4500 the equilibrium mixture is richer in reactants than products

25. T
Reaction rates are always increased when the temperature is raised.

1. T	Energy is needed to break covalent bonds.
2. T	Energy is released when a covalent bond is formed.
3. F	All covalent bonds are the same strength.
4. T	Compounds with weak bonds react quickly.
5. F	The heat of reaction is always positive for an exothermic reaction.
6. T	The Law of Conservation of energy says the energy in the universe is constant.
7. F	A spontaneous reaction is one that produces an explosion
8. T	Entropy, S, increases when disorder increases.
9. T	Free energy is the energy available from a reaction that can be used for other purposes.
10. T	Activation energies are high for slow reactions.
11. F	Reactions occur more slowly if the temperature is raised.
12. F	A reaction with an activation energy of 350,000 calories is fast.
13. T	The reaction is most likely exothermic CHCH + H₂ ---> CH₃CH₃
14. T	Entropy is always increasing. It is not governed by a conservation law.
15. T	Reaction rates increase when the concentration of reactants increases
16. T	Catalysts increase reaction rates and are not consumed in the reaction.
17. T	Reactions at equilibrium have a constant ratio of reactants to products.
18. T	An equlibrium system can be altered by changing the temperature of the system.
19. T	The equilibrium expression for the equation C₂H₂ + 2 H₂ --> CH₃CH₃has H₂ in the bottom.
20. T	The rate of a reaction depends on the way molecules contact one another in collisions.
21. T	Enthapy change is the fancy word for energy transfer under constant pressure.
22. T	The Greek symbol delta, D , is used to represent "change".
23. F	The equilibrium constant for a reaction indicates the speed of the reaction.
24. F	When K = 4500 the equilibrium mixture is richer in reactants than products
25. T	Reaction rates are always increased when the temperature is raised.