Smithycroft Secondary

National 4 Chemistry Unit 2

Nature’s Chemistry

Question Booklet

Fuels

1. What is meant by the word ‘fuel’?

2. Give three ways in which the formation of coal and oil are similar.

3. We describe fossil fuels as being ‘finite resources’. What do we mean by this?

4. The questions which follow are based on the table below.

C N2 H2

He O2 CO2

a) These 2 gases make up more than 98% of the air.

b) All fuels need this gas to allow them to burn.

c) This gas turns lime water milky.

d) This gas relights a glowing splint.

e) This is a solid fuel.

f) This is a gaseous fuel.

5. Complete the word equation for the complete combustion of methane.

methane + …….………….. ………………………… + …………………………..

6. Draw and describe the fire triangle.

7. A liquid X is made of only 2 elements. It burns to produce 2 products. One is a colourless

liquid which freezes at 0 oC and boils at 100 oC; the second turns limewater a milky colour.

a) Name the 2 products.

b) Name the 2 elements present in element X.

c) What type of substance is liquid X?

8. A hydrocarbon is burnt is a limited amount of oxygen.

a) Which harmful gas is produced?

b) How does this gas harm the body?

9. When fossil fuels burn, they produce carbon dioxide.

a) Name and describe the environmental issue linked to carbon dioxide in the

atmosphere.

b) Describe a method of reducing the amount of carbon dioxide emitted into the

atmosphere.

10. When coal is burned, the acidic gas sulphur dioxide is produced.

a) What element must be present in the coal?

b) What environmental problem is caused by sulphur dioxide being released into the

atmosphere?

11. Read the following information about biofuels and then answer the questions below.

Biofuels are fuels made from any kind of plant or animal material. Even waste material, such as used oil from fast-food restaurants, can make biofuels.

Ethanol is one example of a biofuel. Ethanol is made from grain crops, such as corn. Like most biofuels, it is used to replace gasoline and diesel fuels.

Biofuels may contribute less to global warming than other fuels. Both biofuels and fossil fuels release carbon dioxide when burned. However, crops grown for biofuels also remove carbon dioxide from the air as they grow.

a) What raw materials can be used to make biofuels?

b) Why are biofuel crops a renewable energy resource?

c) How does the use of biofuels affect the cost of food?

d) List two possible sources of biofuels.

e) What is the primary use of biofuels?

12. Hydrogen gas can be used as an alternative fuel.

a) Give one advantage of using hydrogen as a fuel for cars over petrol.

b) Give one disadvantage of using hydrogen as a fuel.

13. The diagram represents the carbon cycle.

a) Name the processes X and Y in the carbon cycle.

b) Name another process which releases carbon dioxide into the atmosphere.

14. Copy out the sentences below and fill in the missing word(s). The answers are shown

jumbled up in brackets at the end of the question.

a) Nuclear power stations use a metal called _____________________ . (manuriu)

b) Uranium is dangerous because it can cause illnesses like _____________________ . (ccaenr)

c) Renewable energy sources will _____________________ run out. (eenvr)

d) Solar cells turn energy from the Sun directly into _____________________ . (eelcitycrit)

e) A _____________________ can be powered by a solar cell. (torulacalc)

f) Solar panels can be used to provide _____________________ _____________________ to

homes. (oht wrate)

g) A biomass fuel is one made from _____________________ and _____________________

and their waste. (stnpla, slaanim)

h) Wood is an example of a _____________________ fuel. (miaboss)

15. Which of the following energy sources which do not rely on the Sun:

coal nuclear power hydroelectric power tidal power

biomass oil geothermal

Hydrocarbons

1. What is meant by a ‘hydrocarbon’?

2. Crude oil is a mixture of chemical compounds. Before the compounds can be used, the crude oil must be

separated into fractions. Use the diagram opposite to describe how crude oil is separated into its fractions.

3. Give the meaning of the following words.

a) flammable

b) viscous

c) fractional distillation

4. The following questions refer to properties of fractions, collected over the temperature

ranges shown:

Fraction Temperature range (0C)

1

2

3

4

5

<40

40-75

150-240

220-250

250-350

Decide whether each of the following statements about the fractions is TRUE or FALSE.

a) Fraction 3 is more viscous than fraction 5

b) Fraction 2 changes to a gas more readily than 4

c) Fraction 3 is less flammable than fraction 4.

d) Fraction 1 has a higher boiling point than fraction 5.

e) Fraction 2 burns more easily than fraction 5

5. Crude oil contains a mixture of chemicals. The table compares the composition of a sample of crude oil from the North sea with one from an oil field in the Middle East.

Chemicals % of chemicals in two samples of oil

North sea crude Middle East crude

Gases

Petrol

Kerosene and diesel

Residue

7

20

30

43

6

14

25

55

a) Use the information in the table to suggest one reason why North Sea crude oil might be more useful than Middle East crude oil for modern day needs.

b) Name the process used to separate the different chemicals in crude oil.

c) Draw one bar chart to represent all the information shown above.

6. Distillation of crude oil produces several fractions.

A B C

kerosene petrol gases

D E F

diesel lubricating oil tar (residue)

Use the box letters only to answer the following questions.

a) Identify the fraction which is used as a fuel for jet aircraft.

b) Identify the fraction with the lowest boiling point

c) Identify the fraction which is in most demand.

d) Identify the fraction which has the highest viscosity.

e) Identify the fraction which is the most flammable liquid.

7. A student carried out an experiment to investigate the viscosity of different oils.

He timed how long it took for a marble to fall through 100cm3 of each oil fraction.

His results are shown in the table.

Put the oils in order of viscosity, starting with the least viscous first.

8. How many carbon atoms are in the following chemicals?

a) octane b) pentane c) propane d) heptane

9. Name the alkane that contains

a) 1 carbon atom b) 4 carbon atoms c) 6 carbon atoms d) 2 carbon atoms

10. Write the general formula for the alkanes.

11. Write the molecular formula for each of the following chemicals

a) butane b) methane c) octane

12. Draw the full structural formula for the compounds in question 11.

13. Alkenes are ‘unsaturated’ hydrocarbons.

a) What is meant by an ‘unsaturated’ hydrocarbon?

b) Describe the test for unsaturation, and the positive result.

14. Write the general formula for the alkenes.

15. Name the alkene that contains

a) 3 carbon atoms b) 5 carbon atoms c) 7 carbon atoms

16. Write the molecular formula for

a) ethene b) hexane c) octene

17. Draw the full structural formula the compounds in question 16.

18. Explain why methene cannot exist.

19. The names of some hydrocarbons are shown.

a) Identify the hydrocarbon which is the first member of the alkene family.

b) Identify the hydrocarbon with six carbon atoms in each molecule.

c) Identify the hydrocarbon with a boiling point of 30oC.

You may wish to use the data booklet to help you.

A B C

D E F

d) Identify the hydrocarbon with the molecular formula C5H12.

20. Write the names for

a) CH2=CH2 b) CH3 CH= CH CH3

c) CH3 CH2 CH= CH CH2 CH3 d) CH3 CH2 CH2 CH= CH2

A

ethene

B

propene

C

pentane

D

butane

E

hexene

F

pentene

A B C

D E F

A B C

D E F

A B C

D E F

21. Butene has the structural formula shown below.

Butene reacts with hydrogen gas.

Draw the molecular formula for the product of the reaction.

22. Different hydrocarbons have the following formulae.

A

CH4

B

C2H4

C

C6H14

D

C5H12

E

C3H8

F

C4H8

a) Identify the molecular formula for pentane.

b) Identify the two molecular formulae which represent alkenes.

A B C

D E F

A B C

D E F

23. a) Describe what is meant by ‘cracking’.

b) Explain why cracking is important.

c) Complete the equation to show what happens when decane is cracked.

C10H22 C6H14 + ……………………………..

24. Silanes are a series of silicon compounds. They are similar to alkanes. In the table:-

a) write the name of the silane with the formula Si2H6.

b) write the formula for tetrasilane.

Formula Name Structural Formula

SiH4 monosilane

Si2H6 (a)

Si3H8 trisilane

(b) tetrasilane

H

H Si H

H H

H Si Si H

H H H

H Si Si Si H

H H H H

H Si Si Si Si H

Everyday Consumer Products

1. Which elements are present in carbohydrates?

2. Give the names of four carbohydrates.

3. Name the carbohydrate produced during photosynthesis.

4. Write a word equation for photosynthesis.

5. What is the chemical formula for glucose?

6. A student made some statements about glucose.

Identify the two correct statements.

7. Describe how starch molecules are made from glucose molecules. You may wish to use a diagram to help you.

8. Describe and explain what is seen when a strong beam of light is shone through glucose solution and a starch “solution”.

9. Describe how Benedict’s Solution is used to distinguish between different sugars.

10. Describe how to distinguish between starch and sugars using iodine solution.

11. Explain why starch needs to be broken down into glucose during digestion.

12. Explain the role of enzymes in the digestion process.

A Glucose is a carbohydrate.

B Glucose is insoluble in water.

C Glucose is made during photosynthesis.

D Iodine solution can be used to test for glucose.

E Glucose molecules are too large to pass through the gut wall.

A B C D E

13. Harry set up an experiment to investigate the burning of carbohydrates.

His results are shown below.

a) Which carbohydrate, starch or sucrose, released the most heat energy?

b) Harry used the same volume of water in each experiment.

Suggest another variable which would have to be kept the same to make a fair

comparison.

c) Animals and plants obtain energy by breaking down carbohydrates. Name this process.

14. A pupil set up the apparatus shown to investigate the rate of photosynthesis.

Oxygen gas was produced by the plant was collected in the test tube.

A pupil set up the apparatus shown to investigate the rate of photosynthesis.

Oxygen gas produced by the plant was collected in the test tube.

Distance of lamp from plant/cm

Number of bubbles of oxygen gas produced in one minute

30

40

60

100

24

19

10

4

a) What effect does the distance of the lamp from the plant have on the number of

bubbles of oxygen gas produced?

b) Give one factor that needs to be kept the same to make this experiment fair.

15. Plants make glucose and oxygen gas during photosynthesis.

a) (i) State the test for oxygen gas.

(ii) What are the names of substances X and Y on the diagram below,

b) A student set up an experiment to investigate the rate of photosynthesis in different plants.

The rate of photosynthesis was measured by counting the number of bubbles of oxygen gas produced in 3 minutes.

The results of the investigation are shown in the table.

(i) Draw a bar graph to show the information in the table.

(ii) Suggest one factor that needs to be kept the same to make this investigation fair.

16. Various solutions can be used to identify substances.

A

Iodine solution

B

Lime water

C

Ferroxyl indicator

D

Benedict’s solution

E

Bromine solution

F

pH indicator

a) Identify the solution used to test for glucose.

b) Identify the solution used to test for carbon dioxide.

c) Identify the solution used to test for starch.

17. Explain the importance of respiration and photosynthesis in maintaining the balance of carbon dioxide and oxygen in the air.

18. Explain why the extensive clearing of forests could present dangers to life on earth.

19. Enzymes are biological catalysts. Explain what a catalyst is.

20. What is meant by the phrase a) optimum temperature and b) optimum pH?

21. a) Name the process used to change glucose into alcohol.

b) Write a word equation for this process.

22. Different sources of carbohydrate are used to make different alcoholic drinks. Copy the table and match the source of carbohydrate to the drink(s).

A B C

D E F

A B C

D E F

A B C

D E F

beer, cider, gin, rum, vodka, whisky, wine.

Source Drink

grapes

barley

apples

potatoes

juniper berries

sugar cane

23. How can the concentration of alcohol in an alcoholic beverage be increased?

24. Flowers produce a sweet-tasting liquid called nectar.

Nectar contains a mixture of sugars such as glucose and sucrose.

a) To which family of compounds do glucose and sucrose belong?

b) Glucose can be broken down to produce alcohol.

i) Name this type of chemical reaction.

ii) What is the chemical name for the alcohol produced?

25. Yoghurt is made by fermenting fresh milk. Enzymes help to convert lactose in the milk to lactic acid.

a) What is an enzyme?

b) The diagram shows a molecule of lactic acid.

Write the molecular formula for lactic acid.

c) Sugar can be added to sweeten yoghurt. Suggest why sugar is added after the

fermentation stage and not before.

26. Give three harmful effects of alcohol on health or on society.

Plants to Products

1. Copy and complete the table to show which drugs are derived from which plants and also, what the medicine is used for.

Plant Drug Use

Foxglove Digoxin To treat heart disease

Willow Aspirin Reduce fever/inflammation

Meadowsweet Aspirin Reduce fever/inflammation

Poppies Morphine Painkiller

Chinchona Quina To treat malaria

2. Besides pharmaceuticals (medicines), give two more products that use plant extracts as a

major ingredient.