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Question 1
The Earth has a layered structure and is surrounded by an atmosphere. The data in the table shows the percentages of gases in the Earth’s atmosphere. |
a) | Plot the data in the table on the grid below.
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b) | Describe the method that can be used to determine the volume of oxygen in air experimentally using iron.
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Question 2
Metals are extracted from ores in the Earth’s crust. Some ores contain metal carbonates. |
a) | Name the type of reaction that occurs when a metal carbonate is heated.
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b) | A chemical reaction happens when calcium carbonate is heated. Write down the symbol equation for this reaction. Include state symbols.
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c) | A student used the apparatus below to investigate what happens when metal carbonates are heated. The student:
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The student's results are shown in the table below. |
c) | What type of graph should the student draw from these results? Explain why.
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d) | How did the student know when to stop the clock? Use the diagram to help you answer the question.
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e) | Complete the following sentences. The more reactive the metal in the carbonate is, the time it takes for the production of carbon dioxide to start. Therefore, the most reactive of the carbonates tested is carbonate. more calcium
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Question 3
A student investigated the thermal decomposition of copper carbonate. The student used the apparatus below to measure how long it took for carbon dioxide to be produced. The student also noted what happened during each minute for three minutes. |
a) | Write the symbol equation for the thermal decomposition of copper carbonate. Include state symbols.
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b) | The student wrote down her observations in the table below. |
b) i) | Suggest the reason for the student’s observations between 0 and 60 seconds.
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b) ii) | Explain the student’s observations between 61 and 120 seconds.
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b) iii) | Explain the student’s observations between 121 and 180 minutes.
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Question 4
Metal carbonates undergo a thermal decomposition reaction when heated. |
a) | Which solid product is formed when magnesium carbonate is heated? A magnesium B magnesium oxide C magnesium nitrate D magnesium sulfide
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A student used the apparatus shown below to investigate the thermal decomposition of four metal carbonates. The student heated each metal carbonate for 5 minutes. |
The table shows the student's results. |
b) | Why do the contents of the test tube lose mass during the investigation?
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c) | Explain the results obtained for potassium carbonate.
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d) | State how you can use the reactivity series to predict which metal carbonate reacts most easily when heated.
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Question 5
The graph below shows how the percentage of carbon dioxide in the atmosphere changed in the last 4500 million years. |
a) | Describe how the percentage of carbon dioxide has changed in the last 4500 million years.
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b) | Give two reasons why the percentage of carbon dioxide has changed.
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c) | The graph below shows how the percentage of carbon dioxide in the atmosphere changed in the last 250 years. |
Is the change in the percentage of carbon dioxide a reason for concern? Answer yes or no, and explain the reason for your answer.
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Question 6
A student uses the reaction between phosphorus and oxygen to find the percentage by volume of oxygen in air. The apparatus used is shown in the image below. The student uses excess phosphorus. |
The student measures the volume of air in the tube every minute. The table shows the student’s results. |
a) | Describe and explain what happens to the volume of air in the tube as the phosphorus reacts with oxygen in the air.
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b) | How do the student's results show that all the oxygen has reacted?
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c) | Use the student's results to calculate the percentage of oxygen in air. Give your answer to one decimal place.
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d) | Suggest one change to this experiment that would make the results more accurate.
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Question 7
A student uses the reaction between iron and oxygen to find the percentage by volume of oxygen in air. The apparatus used is shown in the image below. |
The student followed the method below:
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The diagram shows the readings at the start and at the end of the experiment. |
a) | Complete the table below with the student's results, giving all values to the nearest 0.5 cm3.
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b) | The student uses the results in the table to calculate the percentage by volume of oxygen in air. Her calculated value is lower than the expected value. Suggest why.
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c) | The student repeated the experiment using the same apparatus. The results for the second experiment are shown below.
Use this second set of results to calculate the percentage by volume of oxygen in air.
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Question 8
A student used the apparatus in the image below to burn magnesium in air. A strip of magnesium ribbon was placed in a weighed crucible, which was then reweighed. The crucible was heated strongly for several minutes. During heating, the crucible lid was lifted and replaced several times. |
The magnesium was converted into magnesium oxide. After cooling, the crucible and contents were reweighed. |
a) | Name the element in the air that reacted with the magnesium.
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b) | Write down the balanced symbol equation for this chemical reaction.
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c) | Describe the appearance of:
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d) | Why did the student lift the lid several times during heating?
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e) | The student reweighed the crucible and contents. The student found that the mass of the magnesium oxide was lower than expected. Suggest why.
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Question 9
Hydrogen burns in air at a temperature above 100°C to form water. The boiling point of hydrogen is -253°C and the boiling point of water is 100°C. |
a) | Complete the word equation for the reaction that takes place as hydrogen burns. hydrogen + ➔ water oxygen
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b) | Use the information above to complete a balanced symbol equation for the reaction that takes place as hydrogen burns. Include state symbols in your answer.
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c) | Sulfur also burns in air. The product of this reaction is sulfur dioxide. |
c) i) | Which two of the following statements about sulfur dioxide are correct? A sulfur dioxide is acidic when dissolved in water B the formula for sulfur dioxide is S2O C sulfur dioxide is alkaline when dissolved in water D sulfur dioxide is responsible for the formation of acid rain
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c) ii) | State the colour of the flames produced when:
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Question 10
Petrol contains carbon and some sulfur. When petrol is burned, the products of combustion may be released into the atmosphere. These products include carbon dioxide and sulfur dioxide. Explain why some scientists are concerned about the environmental impacts of releasing carbon dioxide and sulfur dioxide into the atmosphere. You should refer to both carbon dioxide and sulfur dioxide in your answer.
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