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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 determine the empirical formula, we first analyze the structure shown in Figure 11. The molecule contains several elements: carbon (C), hydrogen (H), nitrogen (N), and oxygen (O).
Counting the atoms, we find:
- Carbon (C): 4
- Hydrogen (H): 7
- Nitrogen (N): 1
- Oxygen (O): 1
The empirical formula is a simplified version of the molecular formula, showing the ratio of elements. In this case, the empirical formula is written as:
C₄H₇N₁O₁
This can also be simplified further, but since the numbers are all in their simplest ratio, the empirical formula for compound S is C₄H₇NO.
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 assess the purity of the samples, we can evaluate the melting points provided in Figure 12:
- Sample A: Melting point is between 160-164 °C. This range suggests it is impure, as pure substances typically have a sharp melting point.
- Sample B: Melting point is exactly 166 °C. This indicates a sharp melting point, suggesting that it is pure.
- Sample C: Melting point is between 163-165 °C. Similar to Sample A, the range suggests it is impure due to the absence of a distinct melting point.
To summarize:
- Sample A: Impure (range indicates impurities)
- Sample B: Pure (sharp melting point)
- Sample C: Impure (range indicates impurities)