Answer :
Sure, let's break down each part of the question step by step:
a. Describe an experiment that would allow the student to collect these results.
To investigate the decomposition of metal carbonates and collect the gas evolved:
1. Set up the apparatus with a test tube containing a known mass of the metal carbonate.
2. Heat the test tube using a Bunsen burner while ensuring the open end is connected to a delivery tube.
3. Allow the gas evolved to pass through the delivery tube into an inverted measuring cylinder or gas syringe placed in a water trough.
4. Measure the volume of gas collected.
b. Name the gas collected.
The gas collected in the decomposition of metal carbonates is carbon dioxide (CO₂).
c. Write an equation for the reaction occurring with lead(II) carbonate.
The thermal decomposition of lead(II) carbonate can be represented by the following equation:
[tex]\[ \text{PbCO}_3 \xrightarrow{\Delta} \text{PbO} + \text{CO}_2 \][/tex]
d. Name the type of reaction occurring with lead(II) carbonate and copper(II) carbonate.
The type of reaction occurring with lead(II) carbonate and copper(II) carbonate is thermal decomposition.
e. Explain what these results indicate about the thermal stability of sodium carbonate compared to the other two substances.
The results indicate that sodium carbonate is more thermally stable than both lead(II) carbonate and copper(II) carbonate. This is evident because no gas (CO₂) is evolved from sodium carbonate when it is heated, whereas both lead(II) carbonate and copper(II) carbonate decompose and release CO₂.
f. Explain why much more gas is given off in the copper(II) carbonate experiment than in the lead(II) carbonate experiment.
Much more gas is given off in the copper(II) carbonate experiment than in the lead(II) carbonate experiment because:
1. Copper(II) carbonate decomposes more completely or more rapidly under the same heating conditions.
2. The stoichiometry of the reactions may also play a role, where a given mass of copper(II) carbonate may produce more CO₂ compared to the same mass of lead(II) carbonate.
g. Use the data from the lead(II) carbonate experiment to calculate the mass of 100 cm³ of the gas.
From the data given:
- Volume of gas collected at room temperature and pressure (rtp) = 89 cm³
- Density of the gas collected = 0.84 g/L
To find the mass of 100 cm³ of the gas:
1. Convert 100 cm³ to liters: [tex]\[ \text{100 cm}^3 = 0.1 \text{ L} \][/tex]
2. Multiply the volume by the density to find the mass: [tex]\[ \text{mass} = 0.1 \text{ L} \times 0.84 \text{ g/L} = 0.084 \text{ g} \][/tex]
So, the mass of 100 cm³ of the gas is 0.084 g.
h. The student repeated the experiment for copper(II) carbonate and only obtained 152 cm³ of gas this time. Explain two things that could have gone wrong with the second experiment to give this result.
Two possible reasons why less gas was obtained in the second experiment for copper(II) carbonate could be:
1. Incomplete Heating: The copper(II) carbonate might not have been heated sufficiently or evenly, resulting in incomplete decomposition, and thus, less CO₂ production.
2. Leakage in the Apparatus: There could have been a leak in the experimental setup (e.g., at the junctions of the delivery tube or where the test tube is sealed), causing some of the gas to escape before being collected.
3. Contamination or Impurities: There might have been impurities in the copper(II) carbonate or contamination in the test setup, which affected the decomposition process and the volume of gas evolved.
These reasons could lead to discrepancies in the observed volume of gas collected.
a. Describe an experiment that would allow the student to collect these results.
To investigate the decomposition of metal carbonates and collect the gas evolved:
1. Set up the apparatus with a test tube containing a known mass of the metal carbonate.
2. Heat the test tube using a Bunsen burner while ensuring the open end is connected to a delivery tube.
3. Allow the gas evolved to pass through the delivery tube into an inverted measuring cylinder or gas syringe placed in a water trough.
4. Measure the volume of gas collected.
b. Name the gas collected.
The gas collected in the decomposition of metal carbonates is carbon dioxide (CO₂).
c. Write an equation for the reaction occurring with lead(II) carbonate.
The thermal decomposition of lead(II) carbonate can be represented by the following equation:
[tex]\[ \text{PbCO}_3 \xrightarrow{\Delta} \text{PbO} + \text{CO}_2 \][/tex]
d. Name the type of reaction occurring with lead(II) carbonate and copper(II) carbonate.
The type of reaction occurring with lead(II) carbonate and copper(II) carbonate is thermal decomposition.
e. Explain what these results indicate about the thermal stability of sodium carbonate compared to the other two substances.
The results indicate that sodium carbonate is more thermally stable than both lead(II) carbonate and copper(II) carbonate. This is evident because no gas (CO₂) is evolved from sodium carbonate when it is heated, whereas both lead(II) carbonate and copper(II) carbonate decompose and release CO₂.
f. Explain why much more gas is given off in the copper(II) carbonate experiment than in the lead(II) carbonate experiment.
Much more gas is given off in the copper(II) carbonate experiment than in the lead(II) carbonate experiment because:
1. Copper(II) carbonate decomposes more completely or more rapidly under the same heating conditions.
2. The stoichiometry of the reactions may also play a role, where a given mass of copper(II) carbonate may produce more CO₂ compared to the same mass of lead(II) carbonate.
g. Use the data from the lead(II) carbonate experiment to calculate the mass of 100 cm³ of the gas.
From the data given:
- Volume of gas collected at room temperature and pressure (rtp) = 89 cm³
- Density of the gas collected = 0.84 g/L
To find the mass of 100 cm³ of the gas:
1. Convert 100 cm³ to liters: [tex]\[ \text{100 cm}^3 = 0.1 \text{ L} \][/tex]
2. Multiply the volume by the density to find the mass: [tex]\[ \text{mass} = 0.1 \text{ L} \times 0.84 \text{ g/L} = 0.084 \text{ g} \][/tex]
So, the mass of 100 cm³ of the gas is 0.084 g.
h. The student repeated the experiment for copper(II) carbonate and only obtained 152 cm³ of gas this time. Explain two things that could have gone wrong with the second experiment to give this result.
Two possible reasons why less gas was obtained in the second experiment for copper(II) carbonate could be:
1. Incomplete Heating: The copper(II) carbonate might not have been heated sufficiently or evenly, resulting in incomplete decomposition, and thus, less CO₂ production.
2. Leakage in the Apparatus: There could have been a leak in the experimental setup (e.g., at the junctions of the delivery tube or where the test tube is sealed), causing some of the gas to escape before being collected.
3. Contamination or Impurities: There might have been impurities in the copper(II) carbonate or contamination in the test setup, which affected the decomposition process and the volume of gas evolved.
These reasons could lead to discrepancies in the observed volume of gas collected.
