Rates Of Reaction

Question 1

Rate of reaction

Answer 1

Change in concentration of a reactant(or product) per unit time

Question 2

Average rate

Answer 2

The amount of product/ period of time

Question 3

Activation energy

Answer 3

Minimum energy colliding particles must have in order to react

Question 4

Catalyst

Answer 4

A substance that alters the rate of a chemical reaction but is not used up at the end of the reaction

Question 5

Factors affecting rate of reaction

Answer 5

1. Temperature
2. Concentration
3. particle size
4. nature of reactants

Question 6

Temperatures affect on reaction rate

Answer 6

Th higher the Temperature the larger the proportion of particles that have activation energy

Question 7

Particle size affect on reaction rate

Answer 7

The smaller the particles- the faster the rate of reaction due to larger surface area.

Question 8

Nature of reactants

Answer 8

Ionic compounds react very quickly/ covalent compounds react slowly

Question 9

Auto catalyst

Answer 9

One of the products of the reaction catalyses the reaction

Question 10

Why does the rate of chemical reaction generally decrease with time?

Answer 10

Concentration decreases and reactants are used up

Question 11

Give three conditions necessary for a dust explosion to occur

Answer 11

Dryness
Above certain concentration
Enclosed space

Question 12

Effective Collision

Answer 12

Reaches activation energy and results in product formation

Question 13

Homogenous catalyst

Answer 13

Catalyst and reactants are in Same phase

Question 14

Heterogeneous catalysts

Answer 14

Catalyst and reactants in different phases

Question 15

Surface absorption

Answer 15

Reactants are absorbed onto the surface of the catalyst and the products released when formed thus freeing active site again

Question 16

Intermediate compound formation

Answer 16

Catalyst forms unstable intermediate with reactants and decomposes readily releasing the products

Question 17

Explain how the type of bonding in the reactants influences the rate of a chemical reaction in aqueous solutions

Answer 17

Ionic compounds react quickly in solution as dissociated ions only need to collide

Question 18

How could you reduce the rate of reaction that takes place in solution?

Answer 18

Lowering the temperature or lowering the concentration

Question 19

two observations of the oxidation of methanol using platinum wire

Answer 19

Wire glows/ odour of methanol

Question 20

Absorption

Answer 20

The attachment of liquid or gaseous molecules to a solid surface

Question 21

Explain how absorption affects the rate of oxidation

Answer 21

Bonds weekend and lower activation energy/ more effective collisions

Question 22

Explain how a catalyst poison like sulfur interferes with a catalyst

Answer 22

Active site occupied/blocked by poison

Question 23

How does temperature speed up reaction?

Answer 23

The higher the temperature the larger the proportion of particles that have activation energy.

Question 24

How does concentration speed up a rate of a reaction?

Answer 24

Closer molecules means more collisions per unit time

Question 25

How does a catalyst speed up a rate of reaction?

Answer 25

Lowers activation energy/more effective collisions / forms activated complex

Question 26

Name two of the metals used as catalysts in catalytic converters

Answer 26

Platinum

Rhodium

Question 27

Name a substance that could poison the catalysts of the catalytic converter.

Answer 27

Sulfur compounds/ lead compounds

Question 28

Two products in oxidation of methanol using platinum wire as a catalyst

Answer 28

Methanol and hydrogen gas

Question 29

Heat of reaction formula

Answer 29

Heat/no. Of moles