NESA Chemistry Reactions of Organic Acids and Bases

Bromine water is used to test for unsaturation (carbon-carbon double or triple bonds). Since neither butan-2-one nor butanal contains these bonds, neither will react to decolorize the solution.

Hydrochloric acid does not react with either aldehydes or ketones to produce a visible change, making it useless for distinguishing between the two.

Acetic acid with a sulfuric acid catalyst is used for esterification reactions with alcohols. It will not react with either butan-2-one or butanal.

Esters cannot form intermolecular hydrogen bonds, resulting in weaker dipole-dipole interactions and a lower boiling point compared to alcohols and carboxylic acids.

While alcohols can form hydrogen bonds, they do not form stable dimers like carboxylic acids do, resulting in slightly weaker overall intermolecular forces and a lower boiling point than option B.

Amines can form hydrogen bonds, but because nitrogen is less electronegative than oxygen, the N-H bond is less polar than the O-H bond. This makes their hydrogen bonds weaker than those in alcohols and carboxylic acids.

Water is a reactant required to break the ester bond during hydrolysis, not a product of the reaction.

Amines are produced during the hydrolysis of amides, not esters.

Aldehydes are not formed during standard ester hydrolysis; the reaction yields a carboxylic acid and an alcohol.

The hydrophobic end is the non-polar hydrocarbon chain that interacts with grease and oil; it does not react with the metal ions in the water.

While the reaction occurs at the hydrophilic end, the product is an insoluble salt (calcium carboxylate), not a free fatty acid. Fatty acids are typically formed when soap reacts with an acid.

The reaction occurs at the charged hydrophilic head, not the hydrophobic tail, and it results in the formation of insoluble salts rather than fatty acids.

This is a nitrile (propanenitrile). Nitriles are typically synthesized by reacting haloalkanes with cyanide ions, not by reacting oxidation products of alcohols with amines.

This is a primary amine with three carbons. The reaction sequence does not add carbon atoms to the chain, nor does it reduce a functional group to a primary amine.

This is an amino acid (alanine). The reaction produces a simple amide from a carboxylic acid and an amine, not a molecule with both amine and carboxylic acid functional groups on the same carbon.

Polyesters are polymers made of repeating ester linkages, not individual molecules containing both amine and carboxylic acid groups on the same carbon.

Soaps are typically sodium or potassium salts of long-chain fatty acids and do not contain an amine group.

Biodiesel consists of mono-alkyl esters of long-chain fatty acids, which lack the amine group mentioned in the description.

Primary structure refers to the linear sequence of amino acids held together specifically by covalent peptide bonds, not by the various side-chain interactions listed.

Secondary structure, such as $\alpha$-helices and $\beta$-sheets, is primarily stabilized by hydrogen bonds between the backbone amide and carbonyl groups, rather than interactions between side chains.

Quaternary structure refers specifically to the arrangement of multiple polypeptide subunits; while these forces hold subunits together, the question describes the forces defining the 3D fold of a single chain (tertiary structure).

This structure represents butyl propanoate, which would be formed from the reaction of propanoic acid and butan-1-ol, not butanoic acid and propan-1-ol.

This structure is butyl propanoate written in reverse, which is the product of propanoic acid and butan-1-ol.

This structure represents ethyl pentanoate, which would be formed from the esterification of pentanoic acid and ethanol.

Oxidation involves the loss of electrons or the addition of oxygen to a molecule. It is not the reaction mechanism used for exchanging ester groups between triglycerides and alcohols.

While the underlying mechanism is a nucleophilic acyl substitution, this is a broad category. The specific term for the reaction between an ester and an alcohol is transesterification.

Saponification is the base-catalyzed hydrolysis of triglycerides to produce glycerol and fatty acid salts (soap), rather than the reaction involving methanol to exchange ester groups.

Addition reactions typically involve breaking a $\pi$ bond in an unsaturated compound (like an alkene) to add atoms. Ethanol is a saturated molecule, so it does not undergo addition.

Substitution involves replacing one functional group with another (e.g., replacing $-\text{OH}$ with $-\text{Cl}$). While the group changes, the primary characteristic of this reaction is the increase in the carbon's oxidation state.

Esterification is the reaction between an alcohol and a carboxylic acid to form an ester. Reaction 1 produces the carboxylic acid itself from an alcohol, rather than reacting two molecules to form an ester.

This molecule contains a cyano group ($-CN$), making it a nitrile (specifically propanenitrile), not an amide.

This molecule contains an amino group ($-NH_2$) attached to an alkyl chain, identifying it as an amine (ethylamine). An amide requires a carbonyl group adjacent to the nitrogen.

This is an ammonium salt (ammonium acetate), composed of acetate ions and ammonium ions held together by ionic bonds, rather than the covalent carbonyl-nitrogen bond found in amides.

Primary structure refers to the linear sequence of amino acids connected by covalent peptide bonds, not hydrogen bonds.

Tertiary structure is the overall 3D shape determined primarily by interactions between amino acid side chains (R-groups), such as disulfide bridges, hydrophobic interactions, and ionic bonds.

Quaternary structure involves the arrangement of multiple polypeptide subunits held together by inter-chain interactions, rather than intra-chain bonding within a single backbone.

This incorrectly assumes a 1:1 molar ratio of water to glycerol. The hydrolysis of a triglyceride actually requires 3 moles of water per mole of glycerol produced.

This option is incorrect because the reaction is a hydrolysis, which consumes water rather than producing it. Additionally, the mass calculated assumes an incorrect 1:1 molar ratio.

While the mass of water is calculated correctly, the hydrolysis of a triglyceride consumes water as a reactant; it does not produce it.

Both soaps and detergents have non-polar hydrocarbon tails that dissolve in grease, and polar heads that dissolve in water, not grease.

Both soaps and detergents form micelles upon agitation, and their anionic heads are hydrophilic, meaning they dissolve in water rather than grease.

This statement reverses the functional groups; soaps contain carboxylate groups, while synthetic detergents typically contain sulfonate groups.

This formula represents an amine, as it contains an amino group ($\text{-NH}_2$) attached to an alkyl chain rather than a carbonyl group.

This formula represents an ester, which is characterized by the $\text{-COO-}$ functional group linking two alkyl groups.

This formula represents a compound with both a ketone ($\text{-CO-}$) and an amine ($\text{-NH}_2$) group, but they are separated by a carbon atom and not directly bonded to form an amide.