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The molecular formula of butene is C₄H₈ - Edexcel - GCSE Chemistry - Question 4 - 2018 - Paper 1
Question 4
The molecular formula of butene is C₄H₈. Which of the following is the empirical formula of butene? A) CH B) C₂H₂ C) C₄H₈ D) (CH₂)₄ (b) Calculate the relative for... show full transcript
Worked Solution & Example Answer:The molecular formula of butene is C₄H₈ - Edexcel - GCSE Chemistry - Question 4 - 2018 - Paper 1
Step 1
Which of the following is the empirical formula of butene?
Answer
The molecular formula for butene is C₄H₈. To find the empirical formula, we divide the subscripts by the greatest common factor. Here, the greatest common factor of 4 and 8 is 4.
Therefore, dividing both subscripts by 4, we get:
- C: 4 ÷ 4 = 1
- H: 8 ÷ 4 = 2
Hence, the empirical formula is CH₂. The correct answer is B) C₂H₂.
Step 2
Calculate the relative formula mass of butene, C₄H₈.
Answer
To calculate the relative formula mass of butene (C₄H₈), we use the relative atomic masses given:
- Carbon (C) = 12
- Hydrogen (H) = 1
The formula mass is calculated as follows:
Relative Formula Mass = (Number of Carbons × Relative atomic mass of C) + (Number of Hydrogens × Relative atomic mass of H)
Relative Formula Mass = (4 × 12) + (8 × 1) = 48 + 8 = 56
Thus, the relative formula mass of butene is 56.
Step 3
When burnt completely in air, butene forms carbon dioxide and water.
Answer
The combustion reaction of butene can be represented by the equation:
This indicates that one molecule of butene reacts with six molecules of oxygen to produce four molecules of carbon dioxide and four molecules of water.