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Proteins are natural polymers - CIE - A-Level Chemistry - Question 8 - 2019 - Paper 1
Question 8
Proteins are natural polymers. When one particular protein is partially hydrolysed the product mixture includes tripeptide E. a) (i) Describe the conditions that co... show full transcript
Worked Solution & Example Answer:Proteins are natural polymers - CIE - A-Level Chemistry - Question 8 - 2019 - Paper 1
Step 1
Describe the conditions that could be used to hydrolyse E to produce a mixture of three amino acids.
Answer
To hydrolyse tripeptide E into its constituent amino acids, the following conditions can be utilized:
- Reflux: The reaction should be heated under reflux to ensure complete hydrolysis.
- Aqueous Dilute Conditions: Use an aqueous solution which can involve dilute hydrochloric acid (HCl) or sulfuric acid (H2SO4) to facilitate the hydrolysis process.
- Temperature: Maintain a moderate temperature, around 30 °C to 40 °C, to optimize the reaction conditions.
These conditions help ensure that the peptide bonds in the tripeptide are effectively broken down.
Step 2
Draw the structures of the three amino acids produced by this hydrolysis reaction.
Answer
The three amino acids produced by the hydrolysis of tripeptide E can be represented structurally as follows:
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Amino Acid 1:
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Amino Acid 2:
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Amino Acid 3:
Each amino acid corresponds to the correct form required for the given hydrolysis conditions.
Step 3
Name three different types of intermolecular force that exist between pairs of E molecules.
Answer
The three different types of intermolecular forces that can exist between pairs of E molecules are:
- Permanent Dipole-Dipole: This occurs between molecules that have a permanent dipole, generally involving polar groups such as -NH2 and -COOH.
- Hydrogen Bonds: These can form between molecules where one has -NH and the other has -OH or -COOH, allowing for strong attractions due to the presence of hydrogen atoms.
- London Dispersion Forces: These are weak intermolecular forces that arise from temporary dipoles created in all molecules, regardless of their polarity.
Step 4
Draw the structure of a compound that can polymerise to produce a polyamide, without the need for a second monomer.
Answer
A suitable structure that can polymerise to form a polyamide without requiring a second monomer is as follows:
This compound contains the necessary functional groups to allow for the formation of amide linkages upon polymerization.
Step 5
Draw the structures of two different compounds that can polymerise together to produce a polyester with four carbon atoms per repeat unit.
Answer
The two different compounds that can polymerise to produce a polyester with four carbon atoms per repeat unit are:
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Compound 1:
Name: 1,4-butanediol
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Compound 2:
Name: Terephthalic acid
Together, these compounds can undergo condensation polymerization to form the desired polyester.