A student plans an experiment to investigate the yield of propanoic acid when a sample of propan-1-ol is oxidised - AQA - A-Level Chemistry - Question 6 - 2021 - Paper 3
Question 6
A student plans an experiment to investigate the yield of propanoic acid when a sample of propan-1-ol is oxidised.
Figure 4 shows the apparatus that the student pla... show full transcript
Worked Solution & Example Answer:A student plans an experiment to investigate the yield of propanoic acid when a sample of propan-1-ol is oxidised - AQA - A-Level Chemistry - Question 6 - 2021 - Paper 3
Step 1
Give two reasons why the apparatus shown in Figure 4 is not safe.
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Answer
The round-bottomed flask is not clamped, which can lead to it tipping over and causing spills or breakage.
The apparatus is not a sealed system, allowing vapors to escape, which can pose fire or health risks.
Step 2
Give one additional reagent that is needed to form any propanoic acid.
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Answer
Sulfuric acid is needed as a catalyst for the oxidation reaction.
Step 3
State two more mistakes in the way the apparatus is set up in Figure 4.
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The direction of water flow through the condenser is incorrect, as it should enter from the bottom to ensure efficient cooling.
The thermometer is not required for measuring the temperature of the vapor.
Step 4
State the purpose of the small glass beads in the flask in Figure 4.
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The small glass beads are used to prevent 'bumping', ensuring smooth boiling and consistent heat distribution.
Step 5
State the name of the technique used to separate the propanoic acid from the reaction mixture.
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The technique is fractional distillation.
Step 6
Calculate the percentage yield of propanoic acid.
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To calculate the percentage yield, use the formula:
ext{Percentage Yield} = rac{ ext{actual yield}}{ ext{theoretical yield}} imes 100
State a simple chemical test that distinguishes the propanoic acid from the propan-1-ol.
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Answer
Add sodium carbonate. This will produce effervescence with propanoic acid due to the formation of carbon dioxide gas, indicating the presence of a carboxylic acid.
