GCSE AQA Chemistry Reactions of Alkenes & Alcohols: This question is about hydrocarb

Question

This question is about hydrocarbons.

Most of the hydrocarbons in crude oil are alkanes.

Large alkane molecules can be cracked to produce more useful molecules.

The equation shows the cracking of dodecane.

$$C_{12}H_{26} \rightarrow C_{4}H_{10} + C_{6}H_{12} + C_{2}H_{4}$$

Give two conditions used to crack large alkane molecules.

1.
2.

The products hexene and ethene are alkenes.

Complete the sentence.

When alkenes react with bromine water the colour changes from orange to _____________.

Butane ($C_{4}H_{10}$) is an alkane.

Complete the displayed structure of butane.

$$
      H   H
      |   |
H - C - C - H
      |   |
      H   H
$$

A group of students investigated the energy released by the combustion of four hydrocarbon fuels.

Figure 3 shows the apparatus used.

After two minutes

Mass of fuel used in g | Temperature increase of water in °C | Energy released by fuel in kJ | Energy released by 1.0 g of fuel in kJ | Relative amount of smoke in the flame
--- | --- | --- | --- | ---
Hexane, $C_{6}H_{14}$ | 0.81 | 40 | 16.80 | 20.74 | very little smoke
Octane, $C_{8}H_{18}$ | 1.10 | 54 | 22.68 | 20.64 | some smoke
Decane, $C_{10}H_{22}$ | 1.20 | 58 | 24.36 | 20.30 | smoky
Dodecane, $C_{12}H_{26}$ | 1.40 | 80 | 32.30 | 22.79 | very smoky

Calculate the energy released by 1.0 g of decane in kJ.

Energy released = ____________ kJ

Suggest one improvement to the apparatus, or the use of the apparatus, that would make the temperature increase of the water for each fuel more accurate.

Give a reason why this is an improvement.

The students noticed that the bottom of the beaker became covered in a black substance when burning these fuels.

Name this black substance.

Suggest why it is produced.

A student concluded that hexane is the best of the four fuels.

Give two reasons why the results in Table 1 support this conclusion.

In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.

Most car engines use petrol as a fuel.

Petrol is produced from the fractional distillation of crude oil.

Crude oil is a mixture of hydrocarbons.

Sulfur is an impurity in crude oil.

Car engines could be developed to burn hydrogen as a fuel.

Hydrogen is produced from natural gas.

Natural gas is mainly methane.

Describe the advantages and disadvantages of using hydrogen instead of petrol in car engines.

Use the information given and your knowledge and understanding to answer this question.

This question is about hydrocarbons - AQA - GCSE Chemistry - Question 2 - 2016 - Paper 1

Worked Solution & Example Answer:This question is about hydrocarbons - AQA - GCSE Chemistry - Question 2 - 2016 - Paper 1