Chemistry 4.3

Question 1

Explain what happens to rate of reaction when you increase surface area of solid?

Answer 1

Rate increases
More of the solid is accessible
More collisions per unit time
More successful collisions per unit time

Question 2

Explain what happens to rate of reaction when you increase the concentration of the solution

Answer 2

Rate increases
More particles per unit volume
More collisions per unit time
More successful collisions per unit time.

Question 3

Explain what happens to the rate of reaction when you increase the temperature

Answer 3

Rate increases
Particles gain more kinetic energy
More successful collisions per unit time
Higher proportion of collisions are successful
(more particles have energy greater than the activation energy)

Question 4

Explain what happens to the rate of reaction if a catalyst is added

Answer 4

Rate of reaction increases
Catalyst provides an alternative reaction pathway with a lower activation energy.
More particles have the required activation energy
Higher proportion of collisions are successful
More successful collisions per unit time

Question 5

Definition of catalyst

Answer 5

A chemical that speeds up a reaction without being used up

Question 6

Test for oxygen

Answer 6

Relights a glowing splint

Question 7

Example of a catalyst

Answer 7

Manganese (IV) oxide

Question 8

Observations when a metal carbonate is added to acid

Answer 8

Effervescence
Solid disappears

Question 9

Explain how increasing air pressure affects rate of reaction

Answer 9

Rate of reaction increases
More particles per unit volume
More collisions per unit time
More successful collisions per unit time

Question 10

Test for carbon dioxide

Answer 10

Bubble through limewater
Turns cloudy

Question 11

Why can’t sulphuric acid be used for the reaction with marble chips?

Answer 11

Marble chips and sulfuric acid would react to make calcium sulphate which is insoluble and would form a layer on the marble chips, slowing down the reaction

Question 12

Why does rate decrease as time goes on during the reaction of marble chips and hydrochloric acid when marble chips are in excess?

Answer 12

Acid concentration is highest at the start so rate is highest, lots of frequent collisions
Rate decreases as acid becomes more dilute and more particles are used up so less frequent collisions
Rate stops/levels off when all the acid has been used up

Question 13

During the reaction of marble chips and hydrochloric acid, why is cotton wool placed in the neck of the conical flask?

Answer 13

To prevent loss of acid (spray)
or to ensure that only the gas could escape

Question 14

Chemical and word equation for marble chips

Answer 14

CaCO3
Calcium carbonate

Question 15

Apparatus used to measure volume of gas produced

Answer 15

Gas syringe

Question 16

Which collision theories causes proportion of successful collisions to increase?

Answer 16

Increasing temperature and adding a catalyst

Question 17

What is produced that causes the cross to disappear in the reaction between sodium thiosulphate and hydrochloric acid?

Answer 17

Sulfur

Question 18

What is the relationship between concentration and rate

Answer 18

Rate is directly proportional to concentration

Question 19

What does a graph showing direct proportion look like?

Answer 19

A straight line through the origin.

Question 20

What does collision theory state is needed for a reaction to occur?

Answer 20

Particles must collide
Particles must have at least the activation energy

Question 21

The more frequent the collisions the….

Answer 21

faster the reaction rate