3.1.5, 3.3.1, 3.3.2 past paper questions

Question 1

What is the meaning of fraction in fractional distillation?

Answer 1

• Mixture of compounds w/ similar boiling points.

Question 2

Why do carbon dioxide and methane absorb infrared radiation?

Answer 2

• C=O bonds vibrate at IR frequency.

Question 3

Why do straight alkanes have a higher bp than branched?

Answer 3

• Stronger VDW forces between molecules.
• Straight molecules are packed closer together.

Question 4

Give the IUPAC name of chain isomer of but-1-ene?

Answer 4

• Methylpropene.

Question 5

Why do maxwell-boltzmann curves start at the origin?

Answer 5

• There are no molecules with no energy.

Question 6

What effect does lowering the pressure/ amount of molecules have on rate of reaction?

Answer 6

• Particles further apart.
• Fewer frequent successful collisions between gas particles per unit time.

Question 7

What statement is not correct about SO2?
A - It can be removed from car exhaust gases by a catalytic converter.
B - It can be removed from power station flue gases by reaction w/ CaO.
C - It can cause respiratory problems.
D - It can cause acid rain.

Answer 7

• A.

Question 8

SO2 is produced when some fossil fuels are burned. Which of the following statements is true?
A - SO2 can be removed from waste gases in a power station by an acid-base reaction w/ CaO.
B - SO2 is insoluble in water.
C - SO2 is a basic oxide.
D - SO2 is an ionic compound.

Answer 8

• A.

Question 9

Give an equation for a reaction that removes NO in a catalytic converter.

Answer 9

• 2CO + 2NO –> N2 + 2CO2.

Question 10

Which statement is true about the fractional distillation of crude oil?
A - A zeolite catalyst is used.
B - Each fraction is a mixture of HCs.
C - Gaseous fractions are formed by breaking covalent bonds.
D - The fractionating column is hottest at the top.

Answer 10

• B.

Question 11

What is likely to decrease the accuracy of the experiment (disappearing cross)?
A - Rinsing the flask w/ acid before each new experiment.
B - Stirring the solution throughout the experiment.
C - Using the same piece of paper throughout the experiment.
D - Using different measuring cylinders to measure the volumes of acid + sodium thiosulfate.

Answer 11

• A.

Question 12

Will size of conical flask affect rate of reaction?

Answer 12

• Yes, larger conical flasks will increase the time taken.

Question 13

Which statement about molecules in a sample of gas is true?
A - At given temp they all move same speed.
B - At given temp their average kinetic energy is constant.
C - Temp increases there is more molecules w/ most probable energy.
D - Temp decreases there are fewer molecules w mean energy.

Answer 13

• B.

Question 14

What type of alkanes liquefy more easily?

Answer 14

• Longer chain because they have a higher boiling point.

Question 15

Why do CaO and CaCO3 react with SO2 in flue gas desulfurisation?

Answer 15

• Because they neutralise SO2.

Question 16

Why do longer chain alkanes have higher melting points than shorter chain alkanes?

Answer 16

• Because they are larger molecules.
• Stronger VDW’s forces of attraction.

Question 17

Why should sulphur compounds in crude oil be removed before they are used as fuel?

Answer 17

• Because sulphur will react with oxygen to produce SO2
• Which causes acid rain.

Question 18

What are 3 general features of a homologous series of compounds?

Answer 18

• Similar chemical properties.
• Same functional group.
• Same general formula.

Question 19

What are 2 uses of ethene?

Answer 19

• Ripening fruit.
• Making plastics.