Figure 1 shows some compounds made from a halogenoalkane - AQA - A-Level Chemistry - Question 1 - 2017 - Paper 2
Question 1
Figure 1 shows some compounds made from a halogenoalkane.
Figure 1
Compound J
Reaction 1 NaOH(aq) CH3CH2CH2Br
Reaction 2 NH3
Reaction 3
C3H6
0 1 .... show full transcript
Worked Solution & Example Answer:Figure 1 shows some compounds made from a halogenoalkane - AQA - A-Level Chemistry - Question 1 - 2017 - Paper 2
Step 1
Draw the displayed formula of compound J.
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Answer
The displayed formula for compound J is:
H H H
| | |
H–C–C–C–Br
| | |
H H H
Step 2
Name the mechanism for Reaction 2 and give an essential condition used to ensure that CH3CH2CH2NH2 is the major product.
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Name of mechanism: Nucleophilic substitution
Condition: Excess NH3
Step 3
Calculate the mass, in grams, of CH3CH2CH2NH2 produced from 25.2 g of CH3CH2CH2Br in Reaction 2 assuming a 75.0% yield.
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Answer
To calculate the mass of CH3CH2CH2NH2 produced:
Calculate the molar mass of CH3CH2CH2Br:
Molar mass of CH3CH2CH2Br = 25.2 g / (205 g/mol) = 0.123 moles
Applying the yield to find the actual mass produced:
Theoretical mass = moles × molar mass = 0.123 moles × (actual molar mass of CH3CH2CH2NH2 = 12 + 7 + 1 = 12 g) = 12 g
Applying the yield:
Actual mass = 0.75 × Theoretical mass = 0.75 × 12 g = 9 g, rounded to 2 significant figures: 9 g.
Step 4
When Reaction 2 is carried out under different conditions, a compound with molecular formula C3H7N is produced. Draw the skeletal formula of the compound.
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Answer
The skeletal formula of the compound C3H7N is:
H H
| |
H–C–C–C–N–H
| |
H H
Step 5
Identify the functional group in the compound including its classification.
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Answer
The functional group in C3H7N is the amine group (–NH2), classified as a primary amine.
Step 6
Identify the reagent and conditions used in Reaction 3.
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Reagent: NaOH (sodium hydroxide)
Conditions: Ethanol, concentrated heat.
Step 7
Name and outline a mechanism for Reaction 3.
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Name of mechanism: Elimination reaction
Mechanism outline: In this reaction, a hydroxide ion (OH−) acts as a base and abstracts a proton (H+) from a carbon adjacent to the halogen, leading to the formation of a double bond and the elimination of a halide ion (Br−).
