5 (a) (i) Explain why ethylamine is basic.
Ethylamine is considered basic because it has a lone pair of electrons on the nitrogen atom. This lone pair can readily a... show full transcript
Worked Solution & Example Answer:5 (a) (i) Explain why ethylamine is basic - CIE - A-Level Chemistry - Question 5 - 2012 - Paper 1
Step 1
Explain why ethylamine is basic.
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Answer
Ethylamine is considered basic because it possesses a lone pair of electrons on its nitrogen atom, enabling it to accept protons (H^+) from acids effectively. The presence of this lone pair makes ethylamine a strong Lewis base.
Step 2
Write an equation showing ethylamine acting as a base.
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Answer
The equation demonstrating ethylamine acting as a base is:
C2H5NH2+HCl→C2H5NH3++Cl−
Step 3
Write an equation showing ethylamine acting as a nucleophile.
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The equation for ethylamine as a nucleophile is:
C2H5NH2+CH3Br→C2H5N(CH3)Br+HBr
Step 4
Why is phenylamine less basic than ethylamine?
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Phenylamine is less basic than ethylamine due to the influence of the aromatic ring. The lone pair on the nitrogen atom can delocalize into the π-electron system of the ring. This reduces the electron density on the nitrogen, making it less available for protonation compared to ethylamine.
Step 5
Suggest the structure of the product, E, of the reaction between the alkaloid nicotine and an excess of HCl(aq).
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The product, E, formed from the reaction of nicotine with HCl will likely involve the protonation of the nitrogen in nicotine, resulting in a quaternary ammonium salt. The structure can be represented as:
Step 6
Suggest the starting materials needed to synthesise alizarin yellow R.
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Answer
To synthesize alizarin yellow R, the starting materials required include a phenol compound and a diazonium salt. The general structure will involve coupling these components to form the final dye.
Step 7
Suggest the starting materials needed to synthesise methyl orange.
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The synthesis of methyl orange would require a suitable diazonium salt and an amine like dimethylamine. The structure will involve the linking of these materials to create methyl orange.
Step 8
Suggest what effect the NaO3S– group in methyl orange has on its properties.
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The NaO3S– group in methyl orange increases the molecule's hydrophilicity, enhancing its solubility in water due to the potential for hydrogen bonding or ionic interactions. Additionally, it can increase the melting point of the compound.
