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ChemistryKS4 Rates of Reaction

Homework Booklet

Name: _________________________________________Class: _________________________________________Teacher: _______________________________________

Read the Ra01 sections on your knowledge organisers before you begin.

Comprehension Task

When a piece of Magnesium is added to Sulphuric Acid, Hydrogen gas is produced.

a) Use the “insert – shapes” function in Word to draw a curve on the axes below, showing how the volume of hydrogen gas changes over time. of 28

Homework Task Due Date

Teacher Signature

Ra01 Rate of ReactionRa02 Collision Theory and Surface AreaRa03 The Effect of TemperatureRa04 The effect of Concentration and PressureRa05 The effect of CatalystsRa06 Rates RP 1 – Observing Changes in AppearanceRa07 Rates RP 2 – Measuring Volume of Gas ProducedRa08 Reversible ReactionsRa09 Dynamic EquilibriumRa10 Altering Conditions

Ra 01

Rate of Reaction – I should know… R A G

What is meant by the rate of a chemical reaction How to collect data on the rate of a chemical reaction How to calculate mean rate of reaction [H] How to calculate the rate of a reaction using a tangent

Ra01 Reaction Rates Exam Question Practise

Q1. (a) A reaction produced 0.32 g of sulfur in 64 seconds.

Calculate the rate of the reaction using the equation below. Show your working.

Rate of reaction = __________________ grams per second(2)

(b) A solution containing 0.18 g of sodium thiosulfate reacts with dilute hydrochloric acid in 2 minutes.

Comprehension Task

When a piece of Magnesium is added to Sulphuric Acid, Hydrogen gas is produced.

a) Use the “insert – shapes” function in Word to draw a curve on the axes below, showing how the volume of hydrogen gas changes over time.

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Calculate the mean rate of reaction in g / s.

Give your answer in standard form. Show your working.

Mean rate of reaction = ____________________ g / s(3)

Q2.A student investigated how concentration affects the rate of reaction between magnesium and hydrochloric acid.

Figure 1 shows results of the experiment.

Figure 1

(a) Calculate the mean rate of reaction between 0 and 50 seconds.

Use Figure 1 and the equation below. Show your working.

Mean rate of reaction = ______________________ cm3/s(2)

(b) Describe how the rate of reaction changes between 0 and 160 seconds.

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Use Figure 1. (3)

Q3.

(a) A student investigated the rate of reaction by measuring a change in mass.

Figure 2 shows the graph plotted from this student’s results.

Figure 2

Use Figure 2 to calculate the mean rate of the reaction up to the time the reaction is complete.

Give your answer to three significant figures. Show your working.

Mean rate of reaction = ______________________ g / s(4)

(b) Use Figure 2 to determine the rate of reaction at 150 seconds.

Show your working on Figure 2. (Click on the graph and then “insert” a line)

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Give your answer in standard form.

Rate of reaction at 150 s = ______________________ g / s(4)

Ra02

Collision Theory and Surface Area – I should know… R A G

What factors affect the rate of a chemical reaction How rates of reactions can be explained in terms of collisions and

activation energy

How collision theory is used to explain the effect of surface area on reaction rate

Ra03

The Effect of Temperature – I should know…

How increasing temperature affects the rate of reactions How collision theory is used to explain the effect of temperature on

reaction rate Ra04 The Effect of Concentration and Pressure – I should know… R A G

How and why increasing the concentration of reactants in solutions affects reaction rate

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How and why increasing the pressure of reacting gases affects reaction rate

Ra02, Ra03 and Ra04 Collision Theory Exam Question Practise

Q1.(a) The figure below represents the reaction of sulfur dioxide with oxygen.

Oxygen

Sulfur dioxide Sulfur trioxide

The reactants are gases.

When the pressure of the gases is increased, the reaction gets faster.

Complete the sentence.

Comprehension Task

In science, we use models to explain concepts. A model is a way of imagining things we can’t see by representing them as things we can see – for example, we could represent particles as marbles.

Describe how you could use a tray and some marbles to explain reaction rates to a young child. In your description you should include:

How the marbles show particles reacting How you can represent increasing or decreasing the concentration How you can represent increasing the temperature How you can represent changing the surface area

Read the Ra02, Ra03 and Ra04 sections on your knowledge organisers before you begin.

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When the pressure of the gases is increased,

the frequency of the collisions ___________________________________ (1)

(b) The particles need energy to react.

Complete the sentence.

The minimum amount of energy that particles need to react is called

the ___________________________________ energy.(1)

(c) Give one way of increasing the rate of the reaction other than changing the pressure. (1)

(d) Give two reasons why the rate of the reaction increases as the temperature increases.

Tick (✔) two boxes.

The particles move faster.

The particles collide less often.

All the particles have the same energy.

The particles collide with more energy.

The number of particles increases.

(2)

(e) The student concludes that the rate of reaction is greater when the concentration of hydrochloric acid is higher.

Why is the rate of reaction greater when the concentration of hydrochloric acid is higher?

Tick two boxes.

The particles are moving faster

The particles have more energy

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The surface area of magnesium is smaller

There are more particle collisions each second

There are more particles in the same volume

(2)

Q2.A student investigated the rate of reaction of magnesium and hydrochloric acid.

Mg(s) + 2HCl(aq) MgCl2(aq) + H2(g)

The student studied the effect of changing the concentration of the hydrochloric acid.

She measured the time for the magnesium to stop reacting.

Concentration of hydrochloric acid in moles per dm3

0.5 1.0 1.5 2.0

(a) The rate of reaction increased as the concentration of hydrochloric acid increased. Explain why.

(2)

(b) Explain why increasing the temperature would increase the rate of reaction.(3)

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Q3.Marble chips are mainly calcium carbonate (CaCO3).

A student investigated the rate of reaction between marble chips and hydrochloric acid (HCl).

Figure 3 shows the apparatus the student used.

Figure 3

Figure 4 shows the graph plotted from this student’s results.

Figure 4

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(a) Sketch a line on the grid in Figure 4 to show the results you would expect if the experiment was repeated using 20 g of smaller marble chips.

Label this line A.(2)

(b) Explain, in terms of collision theory, how and why the rate of reaction changes when smaller marble chips are used

(3)

Ra05 The Effect of Catalysts – I should know…

What a catalyst is, including examples in chemistry and

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biology How catalysts increase the rate of chemical reactions Why catalysts are important in industry

Ra05 Rates and Catalysts Exam Question Practise


Comprehension Task

The reaction profile below shows 3 curves, A, B and C. Curve A is a chemical reaction that takes place as part of an industrial process. Match curves B and C to one of the following:

Same reactants, but different products made Same reactants, same products, but a catalyst is used.

In each case, justify your answer.

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Q1.

(a) How does a catalyst speed up a reaction?

Tick ( ) one box.

The catalyst lowers the activation energy.

The catalyst gives the reactants extra energy.

The catalyst increases the pressure in the reactor.

(1)

(b) The graph shows a reaction profile diagram for a reaction without a catalyst.

On the graph:

• draw and label an arrow to show the activation energy for the reaction without a catalyst.

• draw the reaction profile diagram for a catalysed reaction(2)

Use the “insert” function to draw this as a “freeform scribble” under “shapes”

Q2.A company manufactures ethanol (C2H5OH).

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The reaction for the process is:

C2H4(g) + H2O(g) C2H5OH(g)

(a) A catalyst is added to increase the rate of the reaction.

Explain how adding a catalyst increases the rate of a chemical reaction. (2)

(b) Suggest why a catalyst is used in this industrial process.

Do not give answers in terms of increasing the rate of reaction. (1)

Ra06 Rates RP 1 – Observing Changes in Appearance – I should know… R A G

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How to measure the rate of a reaction using the change in colour or appearance as an end point.

Ra07

Rates RP 2 – Measuring Volume of Gas Produced – I should know… R A G

How to measure the rate of a reaction by measuring the volume of gas collected over time.

Ra06 and Ra07 Rates RP Exam Question Practise

Read the methods for the rates of reaction RPs before you begin.

Comprehension Task

Rates RP 1 – Observing a Change in Appearance

Write out “CIDER” for the RP measuring the rate of a reaction by observing a change in appearance, using the equipment pictured.

Rates RP2 – Measuring Volumes of a Gas

Write out “CIDER” for the RP measuring the rate of a reaction by collecting a gas produced, using the equipment pictured.

Complete “CIDER” here - TYPE INTO BOX

C

I

D

E

R

Complete “CIDER” here - TYPE INTO BOX

C

I

D

E

R

C – Control VariableI – Independent VariableD –

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Q1.A student investigated the rate of reaction between marble chips and hydrochloric acid.

Figure 5 shows the apparatus the student used.

Figure 5

(a) Table 1 shows the student’s results for one investigation.

Table 1

Timein s

Mass lostin g

0 0.0

20 1.6

40 2.6

60 2.9

80 3.7

100 4.0

120 4.0

On Figure 6:• Plot these results on the grid.

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• Draw a line of best fit.

To plot results, click on the graph and then “insert” shapes. The “freeform scribble” shape can be used for the line of best fit.

Figure 6

(3)

(b) Use Figure 6 to complete Table 2.

Table 2

Mass lost after 0.5 minutes ______ g

Time taken to complete the reaction ______ s

(2)

(c) The equation for the reaction is:

2HCl(aq) + CaCO3(s) → CaCl2(aq) + H2O(l) + CO2(g)

Explain why there is a loss in mass in this investigation. (2)

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(d) The student measured the change in mass of the reactants.

Describe another method, other than measuring the change in mass of the reactions, that the student could have used to find the rate of the reaction between marble chips and hydrochloric acid.

(2)

Q2.A student investigates the effect of concentration on the rate of reaction.

The student reacts sodium thiosulfate solution with dilute hydrochloric acid.

This produces a cloudy mixture.

(a) The cloudiness is produced by the formation of solid sulfur.

How should sulfur be written in the chemical equation for this reaction?

Tick (✔) one box.

S(aq) S(g) S(l) S(s)

(1)

The diagram shows some of the apparatus the student uses.

This is the method used.

1. Measure 40 cm 3 sodium thiosulfate solution into a conical flask.

2. Stand the flask on a piece of paper with a cross drawn on it.

3. Add 10 cm 3 of dilute hydrochloric acid to the flask.

4. Time how long it takes the cross to become no longer visible.

5. Repeat steps 1‒4 twice more.

6. Repeat steps 1‒5 with sodium thiosulfate solutions of different concentrations.

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(b) Which apparatus could be used to measure 10 cm3 of dilute hydrochloric acid?

Tick (✔) one box.

Beaker

Boiling tube

Measuring cylinder

Test tube

(1)

(c) Draw one line from each type of variable to the description of the variable.

(2)

(d) The student draws a new cross for each experiment.

Suggest why this might give inaccurate results. (1)

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(e) The table shows the student’s results for sodium thiosulfate solution with a concentration of 12 g / dm3

Time for cross to become no longer visible in s

Trial 1 Trial 2 Trial 3 Mean

43 78 41 X

Calculate value X in the table.

Do not use any anomalous results in your calculation.

X = ____________________ s(2)

(f) The graph shows some of the student’s results.

Draw a smooth curve of best fit on the graph above. Use the “freeform Scribble” shape under “insert”

(1)

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(g) Another student does the same investigation.

Both students have a similar pattern in their results.

Which word describes investigations performed by different students, which give a similar pattern of results?

Tick (✔) one box.

Accurate

Precise

Reproducible

Valid

(1)

(h) The more concentrated the sodium thiosulfate solution, the less time is taken for the cross to become no longer visible.

Give two reasons why.

Tick (✔) two boxes.

Particles are more spread out

Particles collide more frequently

Particles have more energy

Particles move more quickly

There are more particles in a fixed volume

(2)

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Q3.A student investigated the rate of reaction between sodium thiosulfate solution and dilute hydrochloric acid, as shown in Figure 7.

Figure 7

7

The reaction produced a precipitate, which made the mixture turn cloudy.

The student timed how long it took until she could no longer see the cross.

She calculated the rate of the reaction.

(a) The equation for the reaction is:

Na2S2O3(aq) + 2 HCl(aq) 2 NaCl(aq) + S(s) + SO2(g) + H2O(l)

Name the product that made the mixture go cloudy. (1)

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(b) The student investigated the effect of changing the temperature of the sodium thiosulfate solution on the rate of reaction.

She plotted her results on a graph, as shown in Figure 8

Figure 8

Describe the trends shown in the student’s results. (2)

(c) The student then investigated the effect of changing the concentration of sodium thiosulfate solution on the rate of the reaction.

Suggest two variables the student would need to control to make sure that her results were valid.

(2)

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Ra08

Reversible Reactions – I should know… R A G

What a reversible reaction is How reversible reactions are represented How the direction of reversible reactions can be changed

Ra09

Dynamic Equilibrium – I should know… R A G

The definition of a closed system How a reversible reaction in a closed system can be at

equilibrium

Read the Ra08 and Ra09 sections on your knowledge organisers before you begin.

Comprehension Task The diagram below shows a reversible reaction. White represents reactants, black represents products:

This reaction is at equilibrium. Explain how this reaction can be at equilibrium even though there are more black squares than white squares.

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Ra08 and Ra09 Reversible Reactions and Equilibrium Exam Question Practise

Q1.. The word equation for a reaction is:

hydrated copper sulfate ⇌ anhydrous copper sulfate + water

(a) What does the symbol ⇌ mean?

Tick one box.

Endothermic

Exothermic

Reversible

Polymerisation

(1)

(b) When water is added to anhydrous copper sulphate, the reaction is exothermic

Name the type of reaction when hydrated copper sulphate reacts to form anhydrous copper sulphate and water.

(1)

Q2.This question is about reversible reactions and chemical equilibrium.

Reversible reactions can reach equilibrium in a closed system.

(a) What is meant by a closed system? (1)

(b) Explain what is meant by equilibrium. (3)

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(c) Explain why, when a reversible reaction reaches equilibrium, the reaction appears to have stopped.

(2)

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Ra10

Altering Conditions (HIGHER ONLY) – I should know… R A G

[H] That the composition of an equilibrium mixture can be altered by changing conditions such as concentration

[H] How changing the pressure affects reversible reactions involving gases

[H] How changing the temperature affects reversible reactions


Comprehension Task 1. Bismuth chloride reacts with water in a reversible reaction:

BiCl3 (aq) + H2O (l) ⇌ BiOCl (s) + 2HCl (aq)

What happens to the position of equilibrium in the following cases:

More HCl added to reaction mixture BiOCl filtered out of the reaction mixture

Explain both of your answers

2. Nitrogen dioxide exists in constant equilibrium with dinitrogen tetroxide:

2NO2 (g) ⇌ N2O4 (g)

The forward reaction is exothermic

What happens to the position of equilibrium if the temperature of the reaction is increased?

Explain your answer

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Ra10 Altering Conditions Exam Question Practise

Q1.In industry ethanol is produced by the reaction of ethene and steam at 300°C and 60 atmospheres pressure using a catalyst.

The equation for the reaction is:

C2H4 (g) + H2O (g) C2H5OH (g)

The figure below shows a flow diagram of the process.

(a) Why does the mixture from the separator contain ethanol and water? (1)

(b) The forward reaction is exothermic.

Use Le Chatelier’s Principle to predict the effect of increasing temperature on the amount of ethanol produced at equilibrium.

Give a reason for your prediction. (2)

(c) Explain how increasing the pressure of the reactants will affect the amount of ethanol produced at equilibrium.

(2)

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Q2.

(a) In the Haber process, the reaction of nitrogen with hydrogen to produce ammonia is reversible.

N2(g) + 3 H2(g) 2 NH3(g)

(i) Name a natural resource from which hydrogen is produced. (1)

(ii) The Haber process uses a catalyst to speed up the reaction.

What is the effect of a catalyst on the position of equilibrium in a reversible reaction

(1)

(iii) What happens to the amount of ammonia produced at equilibrium if the pressure is increased?

Give a reason for your answer.(2)

(b) The decomposition of hydrogen iodide into hydrogen and iodine is reversible.

2HI(g) H2(g) + I2(g)

The forward reaction is endothermic.

Suggest what effect, if any, increasing the temperature will have on the amount of hydrogen iodide at equilibrium.

Give a reason for your answer. (2)

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