Rates of Reaction and collision Theory

Question 1

The speed of a reaction depends of 4 factors:

Answer 1

. temperature
. concentration of the reactants (or pressure if the reactants are
gases)
. the presence of a catalyst
. if one of the reactants is a solid, the surface area

Question 2

when the graph is levelled out, what has happened to the reaction

Answer 2

there are no more reactant particles reacting, the reaction has stopped (speed = 0).

Question 3

what’s Rate of Reaction

Answer 3

the speed at which a reaction takes place

Question 4

what are the three main methods of measuring the Rate of Reactions ( describe them ).

Answer 4

CHANGE IN MASS - recording the loss of mass divided by time gives an accurate rate measurement .

VOLUME OF GAS FORMED ( gas syringe ) - recording the volume of gas divided by time gives and accurate rate measurement.

FORMATION OF A PRECIPITATE - recording decrease of light intensity divided time gives an accurate rate measurement.

Question 5

what is a gas syringe used for ?

Answer 5

a gas syringe is used to collect the gas as it is produced during the reaction.

Question 6

what must reaction particles do for reaction to take place ?

Answer 6

they must collide

Question 7

A successful collision happens when the reacting particles have ________ ________

Answer 7

sufficient energy

Question 8

what is ‘Activation Energy’ ?

Answer 8

Activation energy is the minimum energy reacting particles must have when they collide for the reaction to take place.

Question 9

what happens when you increase the Rate of Reaction ?

Answer 9

increasing the Rate of Reaction increases the chance / frequency of successful collisions

Question 10

There are 4 ways of changing the rate of reaction

Answer 10

• temperature
• concentration
• surface area
• catalyst

Question 11

increasing the temperature makes the particles move FASTER or SLOWER / gives MORE or LESS kinetic energy .

Answer 11

MORE KINETIC ENERGY => FASTER

Question 12

Do you have a faster Rate of Reaction if you increase the chance of successful collision

Answer 12

Yes

Question 13

Increasing the concentration increases the number of ________ _________

Answer 13

Reacting particles in one area

Question 14

At a higher pressure, is there MORE or LESS reacting particles in the same space

Answer 14

MORE

Question 15

Breaking a solid into smaller pieces increases what

Answer 15

surface area

Question 16

having a larger surface area provides more space for the reacting particles to collide =>

Answer 16

this INCREASES THE CHANCE of successful collisions - so a FASTER RATE OF REACTION

Question 17

adding a catalyst to the reaction does what ?

Answer 17

lowers the activation energy of the reaction

Question 18

when reactant particles collide, what do they form?

Answer 18

products

Question 19

a catalyst is a substance that SPEEDS UP or SLOWS DOWN a reaction

Answer 19

SPEEDS UP

Question 20

does a catalyst get used up ( consumed ) when added to a reaction

Answer 20

No ( remains unchanged after reaction )

Question 21

By lowering the activation energy ( adding catalyst ) does it have a FASTER or SLOWER Rate of Reaction, that increases the chance of successful collisions

Answer 21

FASTER

Question 22

key point that FASTER REACTION(s) might have then others.

Answer 22

• higher temp
• higher concentration
• larger surface area
• might have catalyst

Question 23

key point that SLOWER REACTION(s) might have then others.

Answer 23

• lower temp
• lower concentration
• smaller surface area
• might not have catalyst

Question 24

A reaction can be followed by measuring the amount of _______formed or by measuring the amount of reactant used up.

Answer 24

products

Question 25

rate can be defined as -

Answer 25

rate of reaction =amount of reactant used or product formed
_____________________________________________
time