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This question is about esters including biodiesel - AQA - A-Level Chemistry - Question 11 - 2019 - Paper 2
Question 11
This question is about esters including biodiesel. An ester is formed by the reaction of an acid anhydride with CH₃CH₂OH. Complete the equation. In your answer sho... show full transcript
Worked Solution & Example Answer:This question is about esters including biodiesel - AQA - A-Level Chemistry - Question 11 - 2019 - Paper 2
Step 1
Complete the equation. In your answer show clearly the structure of the ester. Give the IUPAC name of the ester.
Answer
The reaction between an acid anhydride and ethanol (CH₃CH₂OH) produces an ester. The general balanced equation for the reaction is:
The structure of the ester formed is:
The IUPAC name of the ester is Ethyl propanoate.
Step 2
Step 3
Complete the skeletal formula to show the next part of the hydrocarbon chain to carbon atom number 14. In your answer, show the Z stereochemistry around both C=C double bonds.
Answer
The complete skeletal formula extending to carbon atom number 14 is as follows:
HOOC
||
--C=C-- (C= 13) \
Z Z (C= 12)
--C--C--... (C= 14)
Here, the Z stereochemistry is indicated around the double bonds.
Step 4
Step 5
State how the infrared spectrum of carbon dioxide in Figure 3 is not what you might predict from the data provided in Table A in the Data Booklet.
Answer
The infrared spectrum of carbon dioxide shows absorption bands that are not expected based on simple predictions from tabulated data. Specifically, the peak at 2350 cm⁻¹ indicates a strong absorption that suggests the presence of stretching vibrations, contrary to earlier predictions that may not account for the complexities of molecular interactions.
Step 6
Explain how carbon dioxide causes global warming.
Answer
Carbon dioxide contributes to global warming by absorbing infrared radiation emitted by the Earth. When sunlight reaches the Earth's surface, it is converted to heat, which then radiates back into the atmosphere. CO₂ traps some of this heat, preventing it from escaping into space, thereby increasing the average global temperature.