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?
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Answer
The molecular formula of butene is C₄H₈. To find the empirical formula, we divide the subscripts by their greatest common divisor. The greatest common divisor of 4 and 8 is 4.
Thus:
C: 4 ÷ 4 = 1
H: 8 ÷ 4 = 2
Therefore, the empirical formula of butene is CH₂, which corresponds to option B.
Step 2
Calculate the relative formula mass of butene, C₄H₈.
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Answer
To calculate the relative formula mass of butene (C₄H₈), we sum the relative atomic masses of carbon and hydrogen:
Carbon (C): 4 atoms × 12 = 48
Hydrogen (H): 8 atoms × 1 = 8
Thus, the total relative formula mass is:
extRelativeFormulaMass=48+8=56
Step 3
When burnt completely in air, butene forms carbon dioxide and water.
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Answer
The combustion of butene in air can be represented by the balanced chemical equation:
ightarrow 4 ext{CO}_2 + 4 ext{H}_2 ext{O}$$
The products of this reaction are carbon dioxide (CO₂) and water (H₂O), confirming that when butene is burnt, it yields these substances.