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A refrigerant is a chemical used in cooling processes - Scottish Highers Chemistry - Question 10 - 2022
Question 10
A refrigerant is a chemical used in cooling processes. Some refrigerant compounds can damage the ozone layer. a) The ozone depletion potential (ODP) of a refrigeran... show full transcript
Worked Solution & Example Answer:A refrigerant is a chemical used in cooling processes - Scottish Highers Chemistry - Question 10 - 2022
Step 1
Describe a relationship between the formulae of refrigerant compounds 3, 4 and 5 and their ODP.
Answer
Refrigerant compounds 3 (C₂F₄Cl), 4 (C₂F₃Cl₂), and 5 (C₂F₂Cl₃) display a pattern in their ozone depletion potential (ODP). Specifically, as the number of chlorine atoms increases, the ODP decreases. Hence, compound 3 has a higher ODP due to fewer chlorine atoms compared to compounds 4 and 5.
Step 2
Identify which pair of compounds should be used to show the effect of replacing chlorine atoms with bromine atoms in refrigerant compounds.
Answer
The pair of compounds that should be used is C₂F₄Cl (compound 3) and C₂F₄Br (compound 1). This comparison will illustrate the effect of chlorination versus bromination on ODP.
Step 3
Suggest why carbon dioxide, CO₂, and ammonia, NH₃, have ODP values of 0.00.
Answer
Carbon dioxide, CO₂, and ammonia, NH₃, have ODP values of 0.00 because they do not contain halogen atoms. Halogens are responsible for ozone layer depletion, so the absence of these elements signifies no damaging effect on the ozone layer.
Step 4
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Step 7
Calculate the number of moles of pentafluoroethane required to make this mass of coolant.
Answer
To calculate the moles of pentafluoroethane in a 0.05 kg mixture (50% CH₂F₂ and 50% CF₃CH₂F), we first find the mass of pentafluoroethane:
Mass of pentafluoroethane = 0.05 kg × 0.50 = 0.025 kg = 25 g.
Using the formula for moles:
Thus, approximately 0.21 moles of pentafluoroethane are needed.