chemistry gcse question - thermal decomposition of metal carbonate

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19272917291
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#1
Report Thread starter 7 months ago
#1
idk how to do this question. pls help
Some students investigated the thermal decomposition of metal carbonates. The word equation for the reaction is:
metal carbonate → metal oxide + carbon dioxide
The students made the following hypothesis:
‘When heated the same mass of any metal carbonate produces the same mass of carbon dioxide.’
The students heated a test tube containing copper carbonate. Table 1 shows their results.
Table 1
Time the test tube containing copper carbonate was heated in mins
Mass of test tube and contents in g
0246 17.7 17.1 17.0 17.0
Plan a method the students could use to test their hypothesis.
You should show how the students use their results to test the hypothesis. You do not need to write about safety precautions.
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charco
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#2
Report 7 months ago
#2
(Original post by 19272917291)
idk how to do this question. pls help
Some students investigated the thermal decomposition of metal carbonates. The word equation for the reaction is:
metal carbonate → metal oxide + carbon dioxide
The students made the following hypothesis:
‘When heated the same mass of any metal carbonate produces the same mass of carbon dioxide.’
The students heated a test tube containing copper carbonate. Table 1 shows their results.
Table 1
Time the test tube containing copper carbonate was heated in mins
Mass of test tube and contents in g
0246 17.7 17.1 17.0 17.0
Plan a method the students could use to test their hypothesis.
You should show how the students use their results to test the hypothesis. You do not need to write about safety precautions.
Do you have any ideas?
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VOnlyConnect
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#3
Report 7 months ago
#3
Firstly, start by describing the apparatus- as you are carrying out thermal decomposition, this is usually done using a crucible, clay triangle, gauze and bunsen burner.
Next, think about how you are going to collect the carbon dioxide, this can include using a gas syringe, or collecting by displacing water in an inverted measuring cylinder
Then, talk about the practical details e.g. heat the copper carbonate until there is no further change in mass- heat to constant mass, use tongs to hold the crucible.
Then repeat the experiment for different metal carbonates e.g. calcium carbonate, magnesium carbonate and collect the results
Repeat 3 times for each metal carbonate and calculate a mean, after eliminating anomalies.
In order to use the results to test the hypothesis you need to use the equation to calculate the mass of CO2 produced for each thermal decomposition
The equation for group 2 metal carbonate thermal decomposition is
MCO3 -> MO + CO2 hence the metal carbonate and CO2 react in a 1:1 molar ratio. Therefore calculate the number of moles of the metal carbonate and then multiply it by the Mr of CO2 (44) to calculate the mass of CO2 for each. Then compare to test the hypothesis.
These are some of my initial ideas for how to address this question
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