2. Rate of Reaction

Question 1

What is activation energy?

Answer 1

Activation energy is:

The MINIMUM amount of ENERGY required to cause a REACTION

Question 2

What are the 4 factors that affect the RATE of a reaction?

Answer 2

The 4 factors that affect the rate of a reaction are:

1. Temperature
2. Concentration
3. Surface Area
4. Catalysts

Question 3

What is Collision Theory?

Answer 3

Collision Theory is when REACTING PARTICLES collide with each other to form a CHEMICAL REACTION

Question 4

What is the job of a catalyst?

Answer 4

A Catalyst SPEEDS UP A REACTION

Question 5

What 2 things need to happen for a chemical reaction to take place?

Answer 5

For a chemical reaction to take place, 2 things need to happen:

• the particles need to COLLIDE
• the particles need to have enough ENERGY to REACT

Question 6

4 things affect the RATE of reaction - TEMPERATURE - CONCENTRATION - SURFACE AREA & CATALYST

Answer 6

TEMPERATURE affects the rate of reaction:

At higher temperatures, PARTICLES move more QUICKLY - they COLLIDE more OFTEN & with GREAT ENERGY

Question 7

4 things that affect the RATE of a reaction - TEMPERATURE, CONCENTRATION, SURFACE AREA & CATALYST

Answer 7

CONCENTRATION affect the rate of a reaction:

• HIGHER the CONCENTRATION - the PARTICLES are CROWDED & they COLLIDE more OFTEN
• INCREASING the PRESSURE of reacting GASES also INCREASES the number of COLLISIONS

Question 8

4 things that affect the RATE of a REACTION: temperature, concentration, surface area & catalys

Answer 8

4 things that affect the RATE of REACTION :

• SURFACE AREA

Smaller pieces of a sold have a HIGHER SURFACE AREA to volume ration than larger pieces - so more particles are exposed & COLLIDE so there is a FASTER REACTION

Question 9

What is the RATE OF A CHEMICAL REACTION determined by?

Answer 9

The RATE OF A CHEMICAL REACTION is determined by the FREQUENCY (number of) SUCCESSFUL COLLISIONS per second

Question 10

Required Practical: how change in concentration affect the rate of REACTION

Answer 10

One of the products is SULFUR - sulfur is a SOLID

SULFUR makes the solution go CLOUDY

The CLOUDINESS if called TURBIDITY

Question 11

What is a problem with the disappearing cross experiment?

Answer 11

A problem with the disappearing cross experiment is that DIFFERENT people have DIFFERENT EYE SIGHTS

So with the same experiment, different people could get different results.

Question 12

Why does increasing the temperature increase the rate of a chemical change?

Answer 12

Increasing the temperature INCREASES the rate of CHEMICAL CHANGE because …

• the particles COLLIDE more OFTEN
• the particles have enough energy to COLLIDE

Question 13

What does Independent Variable mean?

Answer 13

An independent variable is one that is CHANGED on PURPOSE eg the concentration of acid

Question 14

What is a catalyst?

Answer 14

A CATALYST is:

• a substance that INCREASES the rate of a CHEMICAL REACTION … WITHOUT being USED UP in the process

Question 15

What are the benefits of using a CATALYST?

Answer 15

The benefits of using a CATALYST are:

• it REDUCES the amount of ENERGY needed for a successful collision
• it makes COLLISIONS more successful
• it SPEEDS UP reactions
• it provides a SURFACE for the molecules to attach to so it INCREASES their chances of BUMPING into each other

Question 16

Why is it important for companies to use CATALYSTS?

Answer 16

Companies can benefit from using catalysts because:

• They SPEED UP reactions and therefore reduce COSTS