Topic 6 - The rate and extent of chemical change

Question 1

What is collision theory?

Answer 1

For a chemical reaction to occur, the reacting particles must collide, and have enough energy to break bonds and start the reaction.

Question 2

What does the rate of a chemical reaction depend on?

Answer 2

1. Collison frequency
2. Energy transferred during collision.

Question 3

What 4 things affect the rate on rate of reaction?

Answer 3

1. Temperature
2. Concentration of a solution of pressure of gas
3. Surface area
4. Catalyst

Question 4

What does equilibrium mean?

Answer 4

At equilibrium the forward and reverse reactions are happenening at the same rate, so the concentration of reactants and products have become balanced.

Question 5

What is Le Chatelier’s principle?

Answer 5

If you change the conditions of a reversible reaction at equilibrium, the system will try to counteract it.

Question 6

What happens when you change the amount of pressure around a reversible reaction?

Answer 6

1. If you increase it the equilibrium reduces it by moving in the direction where there are fewer gas particles
2. If you decrease it, it’s the other way round.

Question 7

What 3 things cause a change to the equilibrium of a reversible reaction?

Answer 7

1. Temperature
2. Pressure
3. Concentration

Question 8

What is the equation to find rate of reaction?

Answer 8

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

Question 9

What are the 3 ways you can measure the rate of a reaction?

Answer 9

1. precipitation and colour change
2. Change in mass
3. Volume of gas given off

Question 10

how can you measure the rate of reaction using precipitaion/colour change?

Answer 10

1. when the initial solution is transparent, and the product is a precipitate which makes the solution is opaque, this method can be used
2. You time how long it takes for a black cross at the bottom of a beaker to disappear

Question 11

What are the cons of the precipitation/colour change method?

Answer 11

1. when the cross appears/disappears is subjective
2. you can’t plot a rate of reaction graph from the results

Question 12

how can you measure the rate of reaction using the cahnge in mass method?

Answer 12

1. place a beaker with a reaction in it on a balance
2. as the gas escapes, the mass shown on the balance will drop
3. take measurements at regular intervals from the balance to create a rate of reaction graph

Question 13

How can you measure the rate of reaction using the volume of gas given off method?

Answer 13

1. attach a gas syring to a beaker with a reaction in it
2. take measurements from the gas syringe at regualar intervals to create a rate of reaction graph

Question 14

What do magnesium and HCl react to release?

Answer 14

hydrogen gas

Question 15

What does sodium thiosulfate and HCl react to produce?

Answer 15

cloudy precipitate

Question 16

Is the forward/reverse reactions of hydrated copper sulfate and anhydrous copper sulfate + water endothermic or exothermic?

Answer 16

1. the forward is endothermic
2. the reverse is exothermic