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Butene reacts with steam to produce butanol - Edexcel - GCSE Chemistry Combined Science - Question 5 - 2016 - Paper 1
Question 5
Butene reacts with steam to produce butanol. C₄H₈ + H₂O → C₄H₉OH (i) Calculate the maximum mass of butanol, C₄H₉OH, that can be produced when 1.4 kg of butene, C₄H... show full transcript
Worked Solution & Example Answer:Butene reacts with steam to produce butanol - Edexcel - GCSE Chemistry Combined Science - Question 5 - 2016 - Paper 1
Step 1
Calculate the maximum mass of butanol, C₄H₉OH, that can be produced when 1.4 kg of butene, C₄H₈, reacts with excess steam.
Answer
To calculate the maximum mass of butanol that can be produced, we start by determining the number of moles of butene in 1.4 kg.
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Convert the mass of butene into grams:
1.4 kg = 1400 g
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Calculate the number of moles of butene using its molar mass:
Molar mass of butene, C₄H₈ = 56 g/mol
Moles of butene = mass (g) / molar mass (g/mol) = 1400 g / 56 g/mol = 25 moles
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From the reaction equation, we see that 1 mole of butene produces 1 mole of butanol:
C₄H₈ + H₂O → C₄H₉OH
Thus, 25 moles of butene can produce 25 moles of butanol.
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Calculate the mass of butanol produced:
Molar mass of butanol, C₄H₉OH = 4(12) + 10(1) + 16 = 74 g/mol
Mass of butanol = moles × molar mass = 25 moles × 74 g/mol = 1850 g
Convert grams back to kilograms:
1850 g = 1.85 kg
Therefore, the maximum mass of butanol produced is 1.85 kg.
Step 2
What type of reaction takes place between butene and steam?
Answer
The type of reaction that takes place between butene and steam is:
A addition.
In this reaction, the steam (water) is added to butene, resulting in the formation of butanol. This process is classified as an addition reaction because no by-products are formed, and the molecular formula of the reactants combines directly to form the product.
Step 3
Using the results, comment on the structures of the hydrocarbons X, Y and Z.
Answer
In the experiment, the behavior of the hydrocarbons when shaken with bromine water indicates their structure:
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Hydrocarbon X: The orange mixture becomes colourless, showing that X is likely to be an alkene or alkyne, as these types of hydrocarbons react with bromine to decolorize it.
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Hydrocarbon Y: Similarly, the orange mixture becomes colourless, suggesting that Y also reacts with bromine in a manner similar to X, hence is also likely unsaturated.
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Hydrocarbon Z: The mixture remains orange, indicating that Z is most likely a saturated hydrocarbon (like an alkane) and does not react with bromine water, confirming its structure does not allow for such reactions.