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Figure 11 shows the structure of a molecule of compound S - Edexcel - GCSE Chemistry - Question 9 - 2023 - Paper 1
Question 9
Figure 11 shows the structure of a molecule of compound S. (i) Use Figure 11 to deduce the empirical formula of compound S. (ii) The melting points of three sample... show full transcript
Worked Solution & Example Answer:Figure 11 shows the structure of a molecule of compound S - Edexcel - GCSE Chemistry - Question 9 - 2023 - Paper 1
Step 1
Use Figure 11 to deduce the empirical formula of compound S.
Answer
To deduce the empirical formula of compound S from Figure 11, we need to identify the number of each type of atom present in the molecular structure.
Upon analyzing the structure, we determine that the molecule consists of:
- 4 Carbon (C) atoms
- 7 Hydrogen (H) atoms
- 1 Sulfur (S) atom
- 2 Nitrogen (N) atoms
Combining these counts gives the empirical formula as:
C₄H₇N₂S.
Step 2
State whether each of these samples, A, B and C, is pure or impure and justify your answers using the information in Figure 12.
Answer
To analyze the purity of the samples based on their melting points:
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Sample A (160-164°C): Since this sample has a melting range, it can be considered impure. A pure substance typically has a sharp melting point, while a range indicates the presence of impurities.
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Sample B (166°C): This sample has a sharp melting point. Thus, it can be classified as pure. A sharp melting point suggests that the sample is not contaminated.
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Sample C (163-165°C): Like Sample A, this one has a melting range, indicating it is impure for the same reasons provided for Sample A.
In conclusion:
- Sample A: Impure
- Sample B: Pure
- Sample C: Impure