(Chapter 4.2) Using Chemistry: Rate of Reactions

Question 1

Define reaction rate

Answer 1

How fast a reaction occurs

Question 2

What would occur if respiration occurred at the same rate as combustion?

Answer 2

The cell receiving the glucose would be burnt beyond functionality

Question 3

Define collision theory

Answer 3

A theory that states particples (atoms, ions, and molecules) must collide in the correct orientation and with enough energy (activation energy)

Question 4

Define (reaction) intermediate

Answer 4

A short-lived molecular entity that is formed from the reactants and reacts further to give the directly observed products of a chemical reaction. Note, the textbook calls it intermediate complex so you probably should remember that too

Question 5

Given the chemical equation, how can one tell if a chemical reaction is reversible?

Answer 5

The sign between the reactants and products will be written with a ‘double head’

Question 6

Define reversible reaction

Answer 6

A reaction that have the reactants and products switched

Question 7

Name the factors that affect the rate of reaction

Answer 7

Concentration, surface area, temperature, pressure (gas), stirring and mixing, and using a catalyst

Question 8

How does the concentration affect the rate of reaction?

Answer 8

Concentration affects the rate of reaction as in more concentrated solution, the participles are closer and collide more

Question 9

How does surface area affect the rate of reaction?

Answer 9

Surface area affects the rate of reaction as if the participles have a larger surface area, there is a larger area to collide with

Question 10

How does temperature affect the rate of reaction?

Answer 10

Temperature affects the rate of reaction as hotter substances have more kinetic energy, which in turn causes the substance to collide more and with more energy

Question 11

How does pressure affect the rate of reaction?

Answer 11

Pressure affects the rate of reaction as to adjust the pressure on gases, you adjust the temperature or concentration

Question 12

How does stirring and mixing affect the rate of reaction?

Answer 12

Stirring and mixing affects the rate of reaction as stirring and mixing moves the products, that already formed, out of the way of the various reactants

Question 13

How does using a catalyst affect the rate of reaction?

Answer 13

Catalysts affect the rate of reaction as a catalyst is any substance that speeds up a chemical reaction but is not used up in the reaction

Question 14

How does the use of catalysts increase the rate of reaction?

Answer 14

Catalysts provide a surface, which the particles of reactants adsorb (stick) onto, to react and form the products. The products are then released and this process repeats itself

Question 15

What substance is nicknamed ‘biological catalysts’ and why?

Answer 15

Enzymes and this nickname is given as they are made from protein molecules and they speed up reactions in cells

Question 16

What is the lock-and-key model?

Answer 16

A model that explains the action of enzymes. The model states enzymes (the lock) have a specific shape, which only specific reactants can fit in (the key). The enzyme brings the reactants in the correct orientation and when products are formed, the products are released as they have a different ‘key’ and the process repeats itself

Question 17

Explain why most food is kept

refrigerated.

Answer 17

The lower temperatures of a refrigerator reduces the rate of reaction

Question 18

Identify the specific term for activation energy in combustion

Answer 18

Ignition