Question 1

Which compound listed in the table has the highest melting point range, and what structural feature likely contributes to this property?

Accepted Answer

4-Nitrobenzoic Acid; due to strong hydrogen bonding and resonance stabilization

Question 2

Given the molecular formula $$\mathrm{C_7H_6O_2}$$, which two compounds from the table share this formula?

Accepted Answer

Benzoic Acid and Salicylic Acid

Question 3

Which compound would you expect to be most soluble in water based on its structure and molecular formula?

Accepted Answer

Urea ($$\mathrm{CH_4N_2O})$$

Question 4

A student isolates a solid with a melting point of $$132-135\ ^\circ\mathrm{C}$$ and a molecular formula of $$\mathrm{CH_4N_2O}. $$Which compound is it?

Accepted Answer

Urea

Question 5

Which compound contains both a nitro group and an aldehyde group?

Accepted Answer

3-Nitrobenzaldehyde

Question 6

If you were to synthesize 3-Chlorobenzoic Acid, which functional groups would you expect to see in its IR spectrum?

Accepted Answer

Aromatic C-H, carboxylic acid O-H, and C=O stretches

Question 7

Which compound would be expected to have the lowest melting point, and why?

Accepted Answer

Biphenyl, due to lack of strong intermolecular forces

Question 8

A compound with the formula $$\mathrm{C_7H_5NO_3}$$ melts at $$55-58\ ^\circ\mathrm{C}. $$Which compound is this, and what is a key functional group present?

Accepted Answer

3-Nitrobenzaldehyde; aldehyde group

Question 9

Which compound is most likely to undergo electrophilic aromatic substitution at the meta position, and why?

Accepted Answer

Benzoic Acid, because the carboxylic acid group is meta-directing

Question 10

Which compound would you expect to have the greatest acidity, and what structural feature is responsible?

Accepted Answer

4-Nitrobenzoic Acid; electron-withdrawing nitro group stabilizes the conjugate base

Question 11

A compound with the formula $$\mathrm{C_8H_8O_2} is $$isolated. Which compound is this, and what is a distinguishing feature?

Accepted Answer

2-Methylbenzoic Acid; presence of a methyl group on the aromatic ring

Question 12

Which compound is commonly used as a precursor in the synthesis of aspirin?

Accepted Answer

Salicylic Acid

Question 13

Which compound would you expect to be the least reactive toward nucleophilic aromatic substitution, and why?

Accepted Answer

Biphenyl; lacks electron-withdrawing groups

Question 14

A student wants to distinguish between benzoic acid and salicylic acid using a simple chemical test. Which test would be most effective?

Accepted Answer

Ferric chloride test for phenols

Question 15

Which compound is most likely to form an intramolecular hydrogen bond, and what effect does this have on its melting point?

Accepted Answer

Salicylic Acid; lowers the melting point compared to benzoic acid

Question 16

Which compound would you expect to have the highest molecular weight?

Accepted Answer

Biphenyl ($$\mathrm{C$$_{12}$$H_{10}})$$

Question 17

Which compound is most likely to be used as a preservative in food and why?

Accepted Answer

Benzoic Acid; inhibits microbial growth

Question 18

Which compound would you expect to have the lowest solubility in water, and why?

Accepted Answer

Biphenyl; nonpolar and lacks hydrogen bonding sites

Question 19

A compound with the formula $$\mathrm{C_7H_5ClO_2} is $$isolated. Which compound is this, and what is a key property?

Accepted Answer

3-Chlorobenzoic Acid; contains a chlorine substituent on the aromatic ring

Question 20

Which compound would you expect to give a positive Tollens' test, and why?

Accepted Answer

3-Nitrobenzaldehyde; contains an aldehyde group

Physical Properties and Structures of Selected Organic Compounds

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