Chemistry GCSE: C6 The Rate and Extent of Chemical Change Flashcards Preview

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Flashcards in Chemistry GCSE: C6 The Rate and Extent of Chemical Change Deck (32)
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1

What do we call the substances that are used in a chemical reaction?

Reactants

2

What do we call the substances that are made in a chemical reaction?

Products

3

What are the four factors that affect the rate of a chemical reaction?

1. The temperature of the reactants

2. The concentrations of the reactants (or the pressure of a gas)

3. The surface area of the reactants

4. Catalysts

4

What is a catalyst?

A substance that speed up a chemical reaction

Without being used up

5

How do catalysts increase the rate of reaction?

They decrease the activation energy (the amount of energy needed for a collision to be successful).

 

So there are more successful collisions.

6

Ellie reacts 1.0M hydrochloric acid with magnesium.

 

What will happen to the rate of reaction if she tries 2.0M hydrochloric acid?

 

Explain why this happens.

 

The rate of reaction will increase.

 

  • There will be more acid particles.
  • Therefore there will be more collisons with magnesium particles.
  • So there will be more successful collisons.

 

7

Charlie reacts sulfuric acid with calcium carbonate at room temperature (20oC).

 

What would happen to the rate of reaction if he repeated the reaction at 25oC?

 

Explain why this happens.

The rate of reaction will increase.

 

  • At higher temperatures the particles have more energy.
  • So they collide more.
  • And the collisions are more energetic.
  • So there are more successful collisions.

8

Milly reacts nitric acid with calcium carbonate chips (small pieces).

 

What would happen to the rate of reaction if Milly used calcium carbonate powder instead of chips?

 

Explain your answer.

The rate of reaction will increase.

 

  • Powder has a larger surface area (to volume ratio).
  • So there are more collisions.
  • And more successful collisions.

9

James is reacting chlorine with magnesium. 

 

What would happen to the rate of reaction if he added a catalyst?

 

Explain why this would happen.

The rate of reaction would increase.

 

  • Catalysts decrease the activation energy.
  • So there are more successful collisions.

10

Micah is reacting oxygen gas with magnesium.

 

What would happen to the rate of reaction if Micah increased the (gas) pressure of the oxygen?

 

Explain why this would happen.

The rate of reaction would increase.

 

  • There would be more oxygen particles.
  • So there would be more collisions.
  • And more successful collisions.

11

In the graph below which line shows the fastest rate of reaction?

 

How can you tell?

The red line.

 

Because it's steeper.

12

Look at the graph below showing how time affects the amount of product made.

 

The red line eventually starts to flatten. What does this mean? Why does it happen?

It means that the reaction has stopped (no more product is formed).

 

Because the rectants have all been used.

13

The graph below shows the carbon dioxide formed when hydrochloric acid reacts with calcium carbonate.

 

  1. Why does the line eventually flatten out? 
  2. How would the line look different if a catalyst was added?

 

  1. Because the reactants (hydrochloric acid and calcium carbonate) have been used up.
  2. The first part of the graph would be steeper (faster rate of reaction). SEE GRAPH BELOW

14

The graph below shows the carbon dioxide formed when hydrochloric acid reacts with calcium carbonate.

 

  1. How would the graph look different if the temperature was increased?
  2. How would the graph look different if smaller pieces of calcium carbonate were used?

 

  1. The first part of the graph would be steeper (faster rate of reaction). SEE GRAPH BELOW
  2. The first part of the graph would be steeper (faster rate of reaction). SEE GRAPH BELOW

15

The graph below shows the carbon dioxide formed when hydrochloric acid reacts with calcium carbonate.

 

How would the graph look different if the concentration of hydrochloric acid was increased?

 

The first part of the graph would be steeper (faster rate of reaction) and the line would flatten out at a higher level (more product formed). SEE GRAPH BELOW

16

How do you calculate rate of reaction?

rate of reaction (g/s or cm3/s) =

reactant used or product formed (g or cm3)

                           Time (s)

17

Give three ways (methods) for measuring rate of reaction.

If a gas is given off you can

1. Measure change in mass

2.  volume of gas given off

 

If a precipitate (insoluble substance) is formed 

3. You can measure how long it takes for the solution to go cloudy/change colour.

18

If you are using the volume of gas produced to measure the rate of a reaction.

 

  1. How would you do this (what equipment would you use)?
  2. Once you had your results, how would you calculate rate of reaction?
  3. What units would you use for rate of reaction?

 

  1. You would carry out the reaction in a flask and use a gas syringe to catch the gas and measure how much is given off.
  2. volume of gas produced divided by time taken.
  3. You would measure the rate of reaction in cm3/s

19

If you are using change of mass to measure the rate of a reaction.

 

  1. How would you do this (what equipment would you use)?
  2. Once you had your results, how would you calculate rate of reaction?
  3. What units would you use for rate of reaction?

 

  1. You would carry out the reaction in a flask and measure the mass of the flas using a mass balance (sensitive scales).
  2. Change in mass divided by time taken.
  3. You would measure the rate of reaction in g/s

20

If you are using precipitate formation or colour change to measure rate of reaction.

 

  1. How would you do this (what equipment would you use)?
  2. What is the problem with this method?

 

  1. You would carry out the reaction in a flask and time how long it takes the colour to change or how long it takes for the solution to go so cloudy you can no longer see through it.
  2. The problem with this method is that it is subjective. Different people will have different opinions about when the solution has changed colour/gone cloudy.

21

How do you calculate mean rate of reaction using a graph?

You divide the total amount of product formed by the time taken (in seconds) to make it.

If you are doing higher tier visit the websites below:

  1. https://www.youtube.com/watch?v=6LV63WtuvJg
  2. https://www.bbc.com/bitesize/guides/z3nbqhv/revision/2

22

1. What is meant by a reversible reaction?

 

2. What symbol do we use to show that a reaction is reversible?

1. A reaction where the products can turn back into the reactants.

 

2. The symbol is shown below

 

 

23

HIGHER TIER: What does it mean when a reversible reaction is at equilibrium?

The reactants are turning into the products at the same speed that the products are turning into the reactants. 

Altough the reactions are still happening, there is no overall change in the concentration of products and reactants.

This does NOT mean that the conentration of reactants and products is the same.

24

Higher tier:

If the equilibrium of a reaction lies to the right, is there a greater concentration of products or reactants?

Products

25

Higher tier:

If the equilibrium of a reaction lies to the left, is there a greater concentration of products or reactants?

Reactants

26

What three factors affect the equilibrium of a reversible reaction?

Temperature

Pressure (of gases)

Concentration

27

Higher Tier

|f a reversible reaction gives out energy (is exothermic) in one direction, what will happen in the opposire direction?

It will take in energy (it is endothermic).

28

Higher tier

What is La Chatelier's principle?

If you change the conditions (temperature, pressure, concentration) of a reversible reaction that is at equilibrium, it will try to couteract the change.

29

Higher tier

Nitogen and hydrogen react to give ammonia. This is a reversible reaction.

The forward reaction (ammonia production) is exothermic.

The reverse reaction (nitrogen and hydrogen formation) is endothermic.

What would happen if I increased the temperature of the reaction?

 

The reverse reaction would increase: More nitrogen and hydrogen would be made

The equilibrium would shift to the left.

The reaction is trying to take in energy (endothermic) to counteract the change (an increase in temperature).

 

30

Higher tier

Nitogen and hydrogen react to give ammonia. This is a reversible reaction. 

What would happen if I increased the concentration of ammonia?

 

The reverse reaction would increase: More nitrogen and hydrogen would be made

The equilibrium would shift to the left.