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2. (a) The molecular formula of butene is C₄H₈ - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2018 - Paper 1
Question 2
2. (a) The molecular formula of butene is C₄H₈. Which of the following is the empirical formula of butene? A CH B CH₂ C C₄H₄ D (CH₂)₄ (b) Calculate the relative... show full transcript
Worked Solution & Example Answer:2. (a) The molecular formula of butene is C₄H₈ - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2018 - Paper 1
Step 1
2(a) Which of the following is the empirical formula of butene?
Answer
The molecular formula of butene is C₄H₈. To find the empirical formula, we need to simplify it to its lowest terms. The subscripts for carbon and hydrogen are 4 and 8, respectively. Dividing both by 4 gives us C₁H₂, which is the empirical formula. Therefore, the correct option is B) CH₂.
Step 2
2(b) Calculate the relative formula mass of butene, C₄H₈.
Answer
To calculate the relative formula mass, we multiply the atomic mass by the number of atoms present:
- For Carbon: 4 x 12 = 48
- For Hydrogen: 8 x 1 = 8
Adding these together gives us: Thus, the relative formula mass of butene is 56.
Step 3
Step 4
2(c)(ii) Describe the test to show that a gas is carbon dioxide.
Answer
To test for carbon dioxide, you can use limewater, which is a solution of calcium hydroxide. When carbon dioxide is bubbled through limewater, it reacts to form calcium carbonate, which is insoluble and causes the limewater to turn cloudy. Therefore, a positive test for carbon dioxide is indicated by the cloudiness of limewater.