C8 Rates & Equilibrium

Question 1

What is the rate of a chemical reaction?

Answer 1

• How fast the reactants are changed into products

Question 2

What are some examples of slow reactions?

Answer 2

• Rusting of iron
• Chemical weathering e.g. acid rain damage to limestone buildings

Question 3

What are some example of moderate reactions?

Answer 3

• The metal, magnesium, reacting w/ acid to produce a gentle stream of bubbles

Question 4

What are some examples of fast reactions?

Answer 4

• Burning
• But explosions are even faster & release a lot of gas
• Explosive reactions are all over in a fraction of a second

Question 5

How do you find the speed of a reaction?

Answer 5

• Record the amount of product formed
• Or find the amount of reactant used up over time

Question 6

How do you read the graph on the rate of reaction?

Answer 6

• The steeper the line on the graph, the faster the rate of reaction
• Over time the line becomes less steep as the reactants are used up
• The quickest reactions have the steepest lines & become flat in the least time

Question 7

What does the rate of chemical reaction depend on (collision theory) ?

Answer 7

1) The collision frequency of reacting particles (how often they collide). The more collisions there are the faster the reaction is. E.g. doubling the frequency of collisions doubles the rate
2) The energy transferred during a collision. Particles have to collide with enough energy for the collision to be successful

Question 8

What is a successful collision?

Answer 8

• A collision that ends in the particles reacting to form products

Question 9

What is the activation energy?

Answer 9

• Minimum amount of energy particles need to react
• Particles need this amount of energy to break the bonds in the reactants & start the reaction

Question 10

What will increase the rate of a reaction?

Answer 10

• Factors that increase the number of collisions (so that a greater proportion of reacting particles collide)
• Or the amount of energy particles collide with

Question 11

What four things does the rate of reaction depend on?

Answer 11

• Tempurature
• The concentration of a solution or the pressure of gas
• Surface area - this changes depending on the size of the lumps of a solid
• The presence of a catalyst

Question 12

What is tempurature in terms of increasing the number of successful collisions between the reacting particles?

Answer 12

1) When the tempurature is increased, the particles all move faster
2) If they’re moving faster, they’re going to collide more frequently
3) Also the faster they move the more energy that have, so more of the collisions will have enough energy to make the reaction happen

Question 13

What is concentration/pressure in terms of increasing the number of successful collisions between the reacting particles?

Answer 13

1) If a solution is made more concentrated, it means there are more