Modern shellac nail varnishes are more durable and so last longer than traditional nail polish - Scottish Highers Chemistry - Question 7 - 2016
Question 7
Modern shellac nail varnishes are more durable and so last longer than traditional nail polish.
(a) The Skin Care Foundation has recommended that a sun-block is app... show full transcript
Worked Solution & Example Answer:Modern shellac nail varnishes are more durable and so last longer than traditional nail polish - Scottish Highers Chemistry - Question 7 - 2016
Step 1
Suggest why the Skin Care Foundation makes this recommendation.
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Answer
The Skin Care Foundation recommends applying sun-block to protect the skin from harmful UV radiation, which can cause sunburn, accelerate skin aging, and increase the risk of skin cancer.
Step 2
State what is meant by the term free radical.
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Answer
A free radical is a species, such as an atom or molecule, that contains unpaired electrons and is highly reactive.
Step 3
State the term used to describe this type of step in a free radical chain reaction.
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Answer
This type of step is known as initiation.
Step 4
Name the functional group circled above.
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The functional group is a carboxylic acid.
Step 5
State why propan-2-ol can be described as a secondary alcohol.
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Answer
Propan-2-ol is a secondary alcohol because the hydroxyl group (-OH) is attached to a carbon that is bonded to two other carbon atoms.
Step 6
Draw a structural formula for butyl ethanoate.
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The structural formula for butyl ethanoate is:
H H H H
| | | |
H-C-C-C-C=O
| | | |
H O H H
| \
H O
Step 7
Suggest why a wet paper towel is wrapped around the test tube.
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A wet paper towel is wrapped around the test tube to condense any vapors or reactants that might evaporate during the reaction, ensuring that they return to the liquid state.
Step 8
Calculate the percentage yield of ethyl ethanoate.
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Answer
To calculate the percentage yield, first determine the theoretical yield. The molar mass of ethanol is 46 g/mol, and ethanoic acid is 60 g/mol.
Calculate moles of ethanol:
moles = mass/molar mass = 2.5 g / 46 g/mol ≈ 0.0543 mol
According to the reaction stoichiometry, it produces an equal amount of ethyl ethanoate. Thus, the theoretical mass of ethyl ethanoate produced:
theoretical mass = 0.0543 mol * 88 g/mol = 4.78 g.
