Sucrose is a carbohydrate - Edexcel - GCSE Chemistry - Question 4 - 2022 - Paper 1
Question 4
Sucrose is a carbohydrate.
When a solution of sucrose is fermented using yeast, ethanol is formed.
sucrose + water ⇌ ethanol + carbon dioxide
In one experiment, ... show full transcript
Worked Solution & Example Answer:Sucrose is a carbohydrate - Edexcel - GCSE Chemistry - Question 4 - 2022 - Paper 1
Step 1
State the meanings of the terms actual yield and theoretical yield.
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Answer
The actual yield refers to the mass of product obtained from a reaction after it has been completed. This can vary due to various factors like inefficiencies in the reaction process or side reactions.
The theoretical yield, on the other hand, is the maximum mass of product that could be formed based on stoichiometric calculations, assuming complete conversion of reactants under ideal conditions.
Step 2
Use the information in Figure 3 to calculate the percentage yield of ethanol in this experiment.
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Answer
To calculate the percentage yield of ethanol, we use the formula:
State two reasons why the actual yield of a reaction is usually less than the theoretical yield.
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Some reactants may remain unreacted due to incomplete reactions.
Side reactions may occur, leading to products that are not the desired outcome, which decreases the overall yield.
Step 4
Calculate the atom economy of this reaction to produce ethanol.
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Answer
To calculate the atom economy, we use the formula:
extatomeconomy=(total mass of reactantsmass of desired product)×100
Where:
Mass of desired product (ethanol) = 4 × 46 g = 184 g
Total mass of reactants = 342 g (C₁₂H₂₁O₁₁) + 18 g (H₂O) = 360 g
Thus,
extatomeconomy=(360184)×100≈51.11%
To two significant figures, the atom economy is 51%.
Step 5
Explain the effect on the atom economy of this reaction if the carbon dioxide produced was used to make fizzy drinks.
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Answer
If the carbon dioxide produced during the fermentation reaction was repurposed for making fizzy drinks, the effective output from the reaction would increase. This would mean a higher utilization of all products formed, boosting the atom economy since more product is being used beneficially, thus increasing the overall efficiency of the reaction.
