This is the most common question on exam papers, although the number of marks for each question may vary.
At its simplest, this type of question will ask you to remember a simple fact that you have been taught. This type of question is likely to be worth one mark, and will often start with 'Give', 'State' or 'Name'. In some cases, a question may ask you to state two things, rather than just one, and will be worth two-marks.
Other structured questions may be worth two or more marks. These will often start with a command word such as 'Describe' or 'Explain', and will require a more detailed answer:
More complex structured questions will be worth three or four marks. They include questions with complex descriptions and explanations, questions in which you need to compare and contrast two different things, or calculations with several stages.
The mark schemes given here may show answers as bullet points. This is to show clearly how a mark can be obtained. However, it is important that your answer is written in a logical, linked way. Examiners will not credit a key word if it is used out of context, or if your answer contradicts itself.
Questions courtesy of Eduqas.
State two factors other than concentration which could affect the rate of the reaction between hydrochloric acid and magnesium. [2 marks]
The following graph shows the effects of temperature and pressure on the yield of ammonia during the Haber process.
Describe how the yield of ammonia varies with temperature and pressure. [2 marks]
The manufacture of ammonia by the Haber process takes place at 400-450°C, 200 atmospheres pressure and using an iron catalyst.
The reaction is exothermic and is shown by the equation:
N2(s) + 3H2(g)⇌ 2NH3(g)
a) Using atmospheric pressure would be safer and cheaper. Explain the effect on yield of using atmospheric pressure in the process. [3 marks]
b) Increasing the temperature would increase the rate of reaction. Explain why a catalyst is used to increase the rate rather than using a higher temperature. [3 marks]
The contact process is used to produce sulfuric acid. One step in this process is the production of sulfur trioxide, shown in the following equation:
2SO2 + O2 → 2SO3
A catalyst of vanadium pentoxide is used in this step.
State the purpose of the catalyst and explain how it is effective in this reaction. [2 marks]