Reaction Energy and Reaction Rates
PART A - REACTION ENERGY
1) Fill in the blanks on the reaction coordinate
diagram with the appropriate letters.
Not all letters will be used
A.
B.
C.
D.
120
90
reactants
products
energy released
energy absorbed
o L=:=====---=-----=-----=-----=-----=-----=-----=-T=__Reaction
_
progn~ss
Specify whether each reaction is exothermic (EXO) or endothermic (ENDO).
2) ____
The reaction shown in the diagram to the right.
3) ____
The burning of wood to produce a hot flame.
4) ___
4Fe(s) + 302(g) --+ 2Fe203(s) + energy
5) ----
A test tube that feels cold to the touch after two substances have been mixed.
PART
B-
REACTION RATES
6) Using the reaction coordinate diagram above, draw a new curve that shows how a
catalyst would affect the reaction pathway.
Place a checkmark next to the actions that would most likely increase the reaction rate.
7) __
Lowering the temperature of the reactants.
8) __
Dissolving two solids in water before mixing them together.
9) __
Diluting an aqueous solution ofHCI with water before adding a piece of magnesium.
10) __
Grinding a solid into fine particles.
11) __
Adding an enzyme catalyst.
12) Explain why all reactions have an activation energy, using your knowledge of collision theory.
13) Describe how the activation energy of a reaction affects the overall rate of the chemical reaction.
14) A rule of thumb used by organic chemists is that increasing the reaction temperature by ten
degrees Celsius can double the rate of a chemical reaction. Explain this drastic increase in
reaction rate using your knowledge of collision theory.
15) It has been observed that more gas station fires occur on hot days than on cold days. Explain
this phenomenon using your knowledge of collision theory. (Hint: It's not just the temperature
increase that causes this!)
16) It has been observed with one variety of paint that the rate of paint drying can be drastically
increased by adding a small amount of "accelerant". Based on what you know of catalysts, is it
reasonable to think of this accelerant as being a catalyst? Explain.