€¦ · web viewq1.carbon dioxide is produced when metal carbonates are heated. (a) (i) draw a...

BBG Academy

Q1.Carbon dioxide is produced when metal carbonates are heated.

(a) (i) Draw a ring around the correct answer to complete the word equation.

(1)

(ii) Draw a ring around the correct answer to complete the sentence.

combustion.

The reaction to produce carbon dioxide from magnesium carbonate is decomposition.

fermentation.

(1)

(b) A student investigated what happens when metal carbonates are heated.

The student:

• used the apparatus to investigate heating four metal carbonates

• started the stop clock at the same time as he began to heat the metal carbonate

BBG Academy

• stopped the stop clock when carbon dioxide was produced.

The student’s results are shown in the table.

Metal carbonate Time taken for the production of carbondioxide to start in seconds

Calcium carbonate 163

Copper carbonate 24

Magnesium carbonate 92

Zinc carbonate 67

(i) Tick ( ) the type of graph the student should draw from these results.

Type of graph Tick ( )

Bar chart

Line graph

Scatter graph

(1)

(ii) Use the Chemistry Data Sheet to help you to answer this question.

Draw a ring around the correct answer to complete the sentence.

less

The more reactive the metal in the carbonate the

more time is taken for the

same

production of carbon dioxide to start.(1)

(iii) How did the student know that carbon dioxide was produced?

Use the diagram of the apparatus to help you to answer this question.

...............................................................................................................

...............................................................................................................

BBG Academy

...............................................................................................................

...............................................................................................................(2)

(Total 6 marks)

Q2. Limestone contains calcium carbonate.

(a) Calcium carbonate has the formula CaCO3.

Complete the sentence by writing in the correct numbers.

The formula of calcium carbonate is made up of 1 calcium atom, ............ carbon atom(s)

and ............ oxygen atom(s).(2)

(b) When limestone is heated it forms two other compounds.

(i) State one safety precaution that you should take when heating limestone.

...........................................................................................................................(1)

(ii) Name the white solid produced.

...........................................................................................................................(1)

(iii) Why does a piece of limestone lose mass as it is heated?

...........................................................................................................................

...........................................................................................................................

BBG Academy

(1)

(d) A company wants to quarry limestone. There are some houses near the quarry.

Residents in the houses say that they do not want a quarry next to them.

(i) Suggest two reasons why they do not want the quarry next to them.

1 ........................................................................................................................

...........................................................................................................................

2 ........................................................................................................................

...........................................................................................................................(2)

(ii) Suggest one possible benefit to the residents of having a quarry near their houses.

...........................................................................................................................

...........................................................................................................................(1)

(Total 8 marks)

Q3. In the UK, railway sleepers are often made from concrete.

BBG Academy

A scientist was asked to find the best concrete mixture to use so that railway sleepers would not break easily.

The scientist made:

• a mould to make small models of concrete sleepers

• concrete mixtures using crushed rock, sand, cement and water

• the equipment shown to add 0.1 kg masses until the model sleeper broke.

The scientist’s results are shown in the table.

Concrete mixturein % by volume

Total mass added to break the model sleeperin kg

Cement Sand Crushedrock Test 1 Test 2 Test 3 Mean

10 70 20 1.1 1.3 1.2 1.2

20 60 20 2.6 2.5 2.4

30 50 20 3.3 3.3 3.3 3.3

40 40 20 3.8 4.0 3.3 3.9

50 30 20 4.5 4.2 4.3 4.3

(a) (i) Calculate the mean total mass added to break the model sleeper that has 20% cement by volume.

...............................................................................................................

BBG Academy

Mean = ........................... kg(1)

(ii) Choose one result in the table that the scientist should check and test again.

Result: % cement by volume ....................... Test number .......................

Explain why you chose this result.

...............................................................................................................

...............................................................................................................(2)

(iii) What is the relationship between the total mass to break the model sleeper and the percentage (%) of cement by volume in the concrete mixture?

...............................................................................................................

...............................................................................................................(1)

(iv) Suggest one other variable that the scientist should have recorded in the table of results.

...............................................................................................................(1)

(b) The scientist thought that full-size railway sleepers should be made from 30% cement, 50% sand and 20% crushed rock.

What other information about these three materials is needed before the scientist recommends using this mixture to make a full-size railway sleeper?

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................(2)

(Total 7 marks)

BBG Academy

Q4. (a) Limestone is a hard rock that is used as a building material.Limestone was used by the Egyptians to make plaster.

Reaction 1 – calcium carbonate, CaCO3, was decomposed by heating limestone

CaCO3 → CaO + CO2

Reaction 2 – water was added to the solid produced to make slaked lime

CaO + H2O → Ca(OH)2

Reaction 3 – a mixture of slaked lime and water was used as plaster. After the plaster had set it became even harder with age

Ca(OH)2 + CO2 → CaCO3 + H2O

(i) Name the solid formed when calcium carbonate decomposed.

...........................................................................................................................(1)

(ii) Use the reactions to explain how the plaster became even harder with age.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(3)

(b) A gardener wanted to make a step up to his greenhouse door. He decided to use a mixture of cement and sand to make mortar.

He experimented using mixtures with different cement to sand ratios.

BBG Academy

• The mortar mixtures were put in the same sized mould.

• Each mortar mixture was allowed to set hard.

• He then dropped a metal ball from increasing heights until the set mortar cracked.

• He recorded his results in a table.

Volume of sandin cm3

Volume of cementin cm3

Height the metal ball dropped to crack the set mortar in cm

800 100 17

700 100 24

600 100 30

500 100 36

400 100 37

300 100 48

200 100 54

(i) What is the relationship between the volume of sand and the strength of the mortar?

...........................................................................................................................

...........................................................................................................................(1)

(ii) The gardener was not sure about some of his results.

Use the results to explain why.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................(2)

(Total 7 marks)

BBG Academy

Q5. Limestone contains calcium carbonate, CaCO3

(a) The flow chart shows the stages in the limestone cycle.

Write the name of the correct calcium compound in each empty box to complete the flow chart.

(3)

(b) Limestone is heated with clay to make cement.Cement is mixed with sand to make mortar.

A student investigated the strength of six mortar mixtures. Each mortar mixture contained 100cm3 cement but each contained a different volume of sand.

BBG Academy

To do the investigation the student:

• added and stirred water into each mortar mixture

• put each mixture into the same sized moulds

• left each mixture to set hard

• dropped a metal ball from increasing heights until the mortar cracked

• recorded the results in a table.

Volume of sand in cm3 Volume of cement in cm3

Height the metal ball was dropped from to crack the

mortar in cm

700 100 24

600 100 30

500 100 36

400 100 37

300 100 48

200 100 54

(i) What happens to the strength of the mortar as the volume of sand increases?

...............................................................................................................(1)

BBG Academy

(ii) The student was worried about an anomalous result.

Which result was anomalous?

Volume of sand = ................. cm3

Explain why you have chosen this result.

...............................................................................................................

...............................................................................................................

...............................................................................................................

...............................................................................................................(2)

(c) The student repeated the investigation but used six concrete mixtures.

From the results the student concluded correctly that concrete was stronger than mortar.

Suggest one reason why concrete is stronger than mortar.

........................................................................................................................

........................................................................................................................(1)

(Total 7 marks)

BBG Academy

M1.(a) (i) magnesium oxide1

(ii) decomposition1

(b) (i) bar chart1

(ii) more1

(iii) limewater1

turns cloudy / milkyaccept forms a white precipitate

1[6]

M2. (a) 1 / one1

3 / three1

(b) (i) (wear safety) glasses / masks / glovesaccept do not handle hot objects / usetongs or accept other safety pointssuch as, ‘tie hair back’

1

(ii) calcium oxideaccept quicklime

1

BBG Academy

(iii) carbon dioxide / CO2 is given offaccept a gas is given off

1

(d) (i) any two from:

• dust / atmospheric pollution

• noise

• eyesore

• destroys habitats

• (extra) traffic

• any other named pollution or description of pollution2

(ii) any one from:

• employment

• increases local trade / makes money

• future development of quarry recreation / park / lake / reservoir do not accept cheaper houses / land / new roads

1[8]

M3. (a) (i) 2.5(kg)ignore units

1

(ii) 40% (cement) and Test 3ignore units

1

because it is anomalous or because it is much lower than the othertwo readings

BBG Academy

accept value not used to calculate meanignore outlier

1

(iii) as the percentage of cement increases the mass needed to break thesleeper increases

allow ‘strength’ for ‘mass needed’allow correct relationship using percentage of sand

1

(iv) volume/percentage / amount of wateraccept temperature

1

(b) any two from:

• availability (of the raw materials)

• cost of the raw materials

• purity (of the raw materials)2

[7]

M4. (a) (i) calcium oxide / quicklimeallow calcium monoxidedo not accept calcium dioxideignore chemical formulae

1

(ii) any three from:

• carbon dioxide / CO2

• (carbon dioxide) reacts (with the calcium hydroxide / slakedlime / plaster)allow reaction 3 identifieddo not allow incorrect reactionignore mixes, unless they state the correct product

BBG Academy

• limestone / calcium carbonate / CaCO3 formsallow marble / chalk

• water is lost / evaporatesit = plasterallow moistureignore dries

3

(b) (i) as the amount / volume of sand decreases the strength of themortar increases

accept as sand decreases the mortar is stronger / harder to crackallow as sand decreases the mortar increasesallow converseignore references to height of metal ball

1

(ii) any two from:

• 400 / 5th result is anomalousaccept two results (36 and 37 / 400 and 500 / 4th and 5th) are almost the sameaccept result at 400 should be 42

• the interval between the others is similar or the intervalis about 6/7allow the other results fit a pattern / are on a straight line

• he has only one set of resultsallow he has only done it onceignore reliable

2[7]

M5. (a) calcium oxide1

calcium hydroxide1

calcium carbonate1

substances must be in the order shown

BBG Academy

(b) (i) strength of mortar decreases (as volume of sand increases)1

(ii) 400 (cm3)1

because the height the metal ball dropped from shouldbe 42 cm and not 37 cm

accept because the other results show that the height the metal ball dropped from should have an interval of 6cm

1

(c) contains aggregateallow bonding is stronger

1[7]

BBG Academy

E1.(a) (i) The majority of students achieved the mark for understanding that when magnesium carbonate is heated the products are magnesium oxide and carbon dioxide.

(ii) The majority of students did not know that the reaction to produce magnesium oxide and carbon dioxide from magnesium carbonate is decomposition.

(b) (i) Less than half of the students realised that the graph must be a bar chart because metal carbonate is a categoric variable.

(ii) Only a few students managed to use the data and the reactivity series of metals to conclude that the more reactive the metal in the carbonate the more time is taken for the production of carbon dioxide to start.

(iii) Most students managed to gain the first mark for identifying limewater. Several thought that the formation of bubbles was evidence that carbon dioxide was produced. Many students also gained the second mark, although several just stated that the limewater changed colour and did not mention that it turned cloudy.

E2. The majority of candidates understood the formula CaCO3 in part (a) and almost all could suggest a reasonable safety precaution that should be taken when heating limestone.

Most candidates were able to name quicklime / calcium oxide but found part (b)(iii) more difficult.

E3. (a) (i) A majority of students successfully scored a mark here by calculating that the mean value was 2.5kg.

(ii) It was very pleasing to see so many selecting the correct result and also

BBG Academy

knowing that it was an anomalous result. Many students were careless in giving their answer as 40% and Test 2 instead of Test 3.

(iii) More than half of the students managed to state the correct relationship. A few students just quoted the figures and did not go on to give the relationship.

(iv) There were not many correct answers. The question was attempted by most students but few stated the variable that should have been recorded was ‘volume of water’ or ‘temperature’. Many students incorrectly suggested ‘time taken to break’, ‘length or weight of the sleeper’, ‘amount of crushed rock added’ or even ‘total mass used’.

(b) This question was poorly answered. Most students did not give answers that referred to ‘information about the three materials’ that is cement, sand and crushed rock. The main correct answers were ‘cost of the materials’ and ‘availability of the materials’.

E4. Foundation Tier

(a) (i) The first part was not well answered, with a large majority of candidates incorrectly identifying the product for example as calcium hydroxide, slaked lime, plaster, limestone or carbon dioxide.

(ii) The hardening of plaster with age also caused problems. Few candidates had any idea what was happening in these reactions. Most did not focus on Reaction 3, although the question clearly stated that this was where the plaster became even harder with age. Very few candidates were able to identify reaction 3 and then go on to explain how the plaster hardened with age by reacting with carbon dioxide to produce the hard material calcium carbonate. The loss of water from the plaster by evaporation was often stated and creditworthy.

(b) (i) This part was well answered with many candidates correctly describing the connection between the volume of sand and the strength of the mortar. The most common error made by candidates was to describe a relationship between the strength of the mortar and the height from which the ball had been dropped without referring to the strength of the mortar.

(ii) Many candidates recognised that there was an anomalous value in the table. This was usually done by reference to the small gap between the 36cm (500g) and 37cm (400g) or by mentioning the large difference between the 37cm

BBG Academy

(400g) and 48cm (300g) values. Some candidates could see that the difference between the 200 and 300 values was 6cm, but didn’t appreciate that this was also the case with the values at the top of the table, missing the idea of a trend. However, a few candidates correctly identified the normal increment between heights was approximately 6 to 7cm or indicated that only one set of results had been obtained.

Higher Tier

(a) (i) The first part was very well answered with a large majority of candidates correctly identifying the product as calcium oxide or quicklime. Incorrect responses included slaked lime, lime, limestone, plaster, carbon dioxide and water.

(ii) The hardening of plaster with age, however, caused problems. A significant minority did not focus on Reaction 3, although the question clearly stated that this was where the plaster became even harder with age. Many candidates were able to identify reaction 3 as the key to explaining how plaster hardened with age and went on to correctly explain how the reaction of plaster and carbon dioxide produced the hard material calcium carbonate. The loss of water from the plaster by evaporation was also creditworthy and often stated. A significant number of candidates, however, merely listed the reactions without explaining anything about the plaster hardening with age. They appeared not to understand the information within the three chemical equations, and tried to explain all three equations, often running out of space before they got to equation 3 and the important information. Some candidates produced reactions that did not happen, especially a reaction between slaked lime and water.

(b) (i) This part was very well answered with the majority of candidates correctly describing the connection between the volume of sand and the strength of the mortar. The most common error made by candidates was to describe a relationship between the strength of the mortar and the height from which the ball had been dropped without referring to the strength of the mortar.

(ii) Most candidates gained at least one mark in the second part, mostly by recognising that there was an anomalous value in the table. This was usually done by reference to the small gap between the 36cm (500g) and 37cm (400g) or by mentioning the large difference between the 37cm (400g) and 48cm (300g) values. Some candidates could see that the difference between the 200 and 300 values was 6cm, but did not appreciate that this was also the case with the values at the top of the table, missing the idea of a trend. However, many candidates correctly identified the normal increment between heights was approximately 6 to 7cm or indicated that only one set of results had been obtained.

BBG Academy

€¦ · web viewq1.carbon dioxide is produced when metal carbonates are heated. (a) (i) draw a...

Documents