Rates Of Reaction Science

Question 1

What is the energy particles must have to react

Answer 1

Activation energy

Question 2

What does a catayls do in a experiment

Answer 2

A catalyst lowers the activation energy increasing the rate of a reaction without being used up

Question 3

How does a catalyst work

Answer 3

They lower the activation energy e.g. provide a surface are for the reactants to bind to

Question 4

When concentration increase explain why the rate of reaction increases

Answer 4

There are more particles in the same volume so collisons are more frequent

Question 5

What would not speed up the chemical reaction

Answer 5

Increasing the particle size

Question 6

Rate of reaction products formed equation

Answer 6

To do this equation you need to divide quantity of products formed by time taken and your units will be cm3/s for example 180cm3 of hydrogen gas in 2 mins because hydrogen is a product you do 180cm3 divided by 120s=1.5cm3/s

Question 7

Reactans used equation

Answer 7

To do this you will need to do reactants used suchas grams and divide it by time taken for example 3g of magnesuim takes 4 mins to dissapear which means you have to do divide 3g by 240s=0.0125g/s

Question 8

To find out moles

Answer 8

You have to do this for example 0.6 moles in 2 minutes you need to do 2 divide by 0.6 which =0.3mol/min

Question 9

State one change that could be made to give more accurate results

Answer 9

Use a pipet to measure acid

Question 10

What property of hydrogen does this method of gas collection depend

Answer 10

Liquid property

Question 11

State two variables that must be kept constant to make the investagtion fair

Answer 11

Same amount of acid
Amount of magnesuim

Question 12

What is a control variable

Answer 12

A control variable is an experimental condition or element that is kept the same throughout the experiment

Question 13

Dependent

Answer 13

The dependent variable is the measure

Question 14

Independent variable

Answer 14

The variable you change

Question 15

Collision theory

Answer 15

For particles to react they have to colldie with each other with sufficient (activation energy)

Question 16

Recall a definition for rate of reaction.

Answer 16

the speed at which a chemical reaction takes place

Question 17

Explain how there can be different units for measuring
rate of reaction.

Answer 17

Either cm3/s or g/s

Question 18

List some factors that can affect the rate of a chemical
reaction.

Answer 18

temperature.
concentration.
particle size.
use of a catalyst.

Question 19

What happends if the tempreture increases

Answer 19

As the tempretue increases particles gain more energy which means they move faster collide more frequently and more likely to exceed activation energy and has a higher rate of reaction

Question 20

What does concentration/pressure do

Answer 20

Concentration/pressure when either is increasd means there will be more particles per unit of volume make the collisons more frequnet and increases the rate of reaction

Question 21

What does surface area do

Answer 21

A solid block of mg or small chunks powder is best because it has the highest surface area and the frequency would be higher which would increase the rate of reaction

Question 22

Tangents

Answer 22

Draw a straight line just touching the curve and the you have to find out the change in the volume of hydrogen divided by change in time the make your line longer so it hits one of the number on the left then trace the other end of it to another number on the left then bring it down to the bottom numbers find the diffrence by subtracting between the two numbers on the left then find the time on the number at the bottom then divide

Question 23

Use collision theory to explain how changing temperature
alters the rate of reaction.

Answer 23

With an increase in temperature, alters it due to increasing the kinetic energy causing particles to bounce around faster and more succesful collsions

Question 24

Use a graph to calculate the rate of reaction at specific
times in a chemical reaction.

Answer 24

change in concentration/change in time

Question 25

State how collision theory explains the effect of surface
area on the rate of reaction

Answer 25

If the surface area of a reactant is increased: more particles are exposed to the other reactant. there is a greater chance of particles colliding, which leads to more successful collisions per second.

Question 26

Calculate the surface area to volume ratio.

Answer 26

divide the surface area by the volume.

Question 27

Use collision theory to explain how changing the
concentration alters the rate of reaction.

Answer 27

Changing the concentration More collisions mean a faster reaction rate.

Question 28

Use collision theory to explain how changing the pressure
of gaseous reactants alters the rate of reaction.

Answer 28

If the pressure of gaseous reactants is increased, there are more reactant particles.

Question 29

Interpret graphs involving rates

Answer 29

The steeper the faster and curve less steep reaction slower and when its flat the reactions over