Chemical reactions study guide

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Chemical reactions study guide

UNIT 4: CHEMICAL REACTIONS: Study Guide ANSWES
1. A substance that undergoes a change in a chemical reaction is a _reactant_.

2. What happens in a chemical reaction? The reactant particles are rearranged to form products by breaking and making bonds.

3. In an exothermic reaction, energy is transferred from the ___system_________ to the __surroundings_______.

4. Making bonds __releases_____________ energy. Breaking bonds ___requires__________ energy.

5. A synthesis reaction is a reaction between at least two compounds in which __one product is formed_______.

6. When methane reacts with abundant amounts of oxygen, the products are __carbon dioxide and water_______.

7. A chemical equation is balanced by changing or adding ____coefficients_________.

8. A balanced chemical equation shows the proportions of reactants and products necessary for ___the mass to be conserved__________________________.

9. In a balanced chemical reaction, the total mass of the products always equals the _mass of the reactants__________________.

10. List the factors that affect rate of reaction.
Particle size: smaller particles – faster reaction
Temperature – higher temperature – faster reaction
Concentration – higher concentration – faster reaction
Agitation – stirring/shaking brings fresh reactant together
Catalyst – increases rate of reaction by providing an alternate energy pathway with lower activation energy.
Inhibitor – decreases rate of reaction by providing an alternate energy pathway with higher activation energy.

11. An enzyme is a special kind of catalyst that works to ___increase the rate of a biological reaction_____________________.

12. When a chemical reaction and its reverse are occurring at the same time and at the same rate, the reaction has achieved ____equilibrium_____________________.

13. What is the relationship between chemical equilibrium and the rates of forward and reverse reaction? ____the rate of forward reaction = the rate of reverse reaction_____________________.

14. In general, if the temperature of a chemical reaction is increased, reaction rate ______increases__________________.

15. Write the balanced equation for the synthesis of sodium bromide from sodium and bromine.
2Na + Br2 à 2NaBr

16. Numbers that precede symbols and formulas in a chemical equation are __coefficients_________.

17. Substances that prevent chemical reactions are called____inhibitors_____________.

18. According to the law of conservation of mass, how does the mass of the products in a chemical reaction compare to the mass of the reactants? The masses must be equal

19. The breaking down of a compound into simpler substances is __decomposition___.

20. A term that means “putting together” is _synthesis____.

21. When one element replaces another element in a compound, the reaction is a _single replacement____ reaction.

22. Explain why energy is necessary to chemical reactions, and describe some common sources of energy. Energy is required to break bonds and energy is released when making bonds. Whichever process is greater determines the overall energy for the reaction. Some common sources of energy in reactions are electricity and thermal energy.

23. Why is it incorrect to balance a chemical equation by changing the subscripts? Explain.
You cannot change the subscripts because by changing the subscripts you change the composition of the substance. For example : H2O is water, H2O2 is hydrogen peroxide

24. Explain how a catalyst affects the rate of reaction and what changes that makes to a reaction coordinate diagram.
A catalyst decreases the time a reaction takes. It increases the reaction rate by lowering the activation energy, which is the energy needed to start a reaction.

25. Explain how each of the five factors that affect reaction rate change the rate of reaction.

See #10
30. __3__NaOH + _____FeCl3 --> ___3__NaCl + _____Fe(OH)3 type:______double replacemnt___________

31. __2__KClO3 --> ___2__KCl + ___3__O2 type:____decomposition________

32. _____S8 + ___12__O2 --> __8___SO3 type:________synthesis_____

33. _____C6H12O6 +___6__O2 --> __6___CO2 + __6___H2O type:___combustion_____

34. _____Fe2O3 + ___3__H2 --> __2___Fe + ___3__H2O type:____single replacement_________

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