CAPE Chemistry Unit 2: Review Flashcards

Comprehensive practice questions covering Module 1 (Organic Chemistry), Module 2 (Analytical Techniques), and Module 3 (Industrial/Environmental Chemistry) for CAPE Chemistry Unit 2.

What is catenation in the context of carbon chemistry?

The ability of carbon atoms to form chains or ring compounds by joining together with strong C—C covalent bonds.

What are the bond energies for C—C, N—N, and O—O single bonds?

$C—C = 350\,kJ\,mol^{-1}$, $N—N = 160\,kJ\,mol^{-1}$, and $O—O = 150\,kJ\,mol^{-1}$.

Define the process of hybridisation in carbon.

The mixing of atomic orbitals (such as s and p) to form new, equivalent hybrid orbitals, such as $sp^3$ or $sp^2$, with mixed character.

How is a $π$ (pi) bond formed in ethene?

It is formed by the sideways overlap of the remaining unhybridised $2p$ orbitals from each carbon atom.

What is a homologous series?

A group of organic compounds with the same functional group where each successive member increases by a $—CH_2$ unit and exhibits similar chemical properties.

Distinguish between an empirical formula and a molecular formula.

The empirical formula shows the simplest whole number ratio of atoms in a compound, while the molecular formula shows the actual number of atoms of each element present.

What is the general formula for the alkane homologous series?

$$C_nH_{2n+2}$$

According to the IUPAC stem name rules, what is the stem for a carbon chain with 7 atoms?

hept-

Define structural isomerism.

Compounds that have the same molecular formula but different structural formulae (e.g., chain, functional group, or positional isomerism).

What condition is required for geometrical (cis-trans) isomerism?

Restricted rotation about a bond, typically a $C=C$ double bond, with different substituent groups on either side.

What is a chiral centre?

A central atom (most commonly carbon) attached to four different groups, resulting in non-superimposable mirror images.

What are the reagents and conditions for the catalytic cracking of alkanes?

A temperature of $400–500^∘C$ and a catalyst of $SiO_2$ and $Al_2O_3$.

Describe the steps of free radical substitution in alkanes.

1. Initiation (homolytic fission by UV light), 2. Propagation (chain reactions forming products), 3. Termination (two radicals combining).

What is an electrophile?

A positively charged or partially positively charged species that attacks an electron-rich area (like a $C=C$ bond).

What is the positive test for an alkene using bromine water?

The orange/red-brown colour of the aqueous bromine changes to colourless.

How can you distinguish primary, secondary, and tertiary alcohols using oxidation?

Primary alcohols oxidise to aldehydes and then carboxylic acids; secondary alcohols oxidise to ketones; tertiary alcohols are resistant to oxidation.

Which reagent is used for the iodoform test and what is a positive result?

Iodine in the presence of sodium hydroxide; it forms a yellow precipitate of triiodomethane ($CHI_3$).

What is the nucleophile in the hydrolysis of halogenoalkanes?

The $:OH^-$ ion or $H_2O:$.

Describe the results of Tollens' reagent with aldehydes versus ketones.

Aldehydes reduce the silver complex to form a silver 'mirror'; ketones show no reaction.

What is the product of the reduction of a ketone using $LiAlH_4$?

A secondary alcohol.

What is saponification?

The hydrolysis of fats and oils with sodium hydroxide to produce glycerol and the sodium salts of long-chain fatty acids (soap).

Explain the electrophilic substitution mechanism in benzene.

An electrophile attacks the delocalised $π$ system to form an unstable intermediate, followed by the loss of a hydrogen ion to regain aromatic stability.

Why is phenol more acidic than ethanol?

The lone pair on oxygen overlaps with the delocalised benzene ring, spreading the negative charge in the phenoxide ion and stabilizing it via the conjugative effect.

Define a zwitterion in the context of amino acids.

An electrically neutral species carrying both a positive ($NH_3^+$) and a negative ($COO^-$) charge in different parts of the molecule.

Distinguish between addition and condensation polymerisation.

Addition polymerisation involves unsaturated monomers forming a polymer as the only product; condensation polymerisation involves monomers reacting with the elimination of a small molecule like $H_2O$ or $HCl$.

What are the common monomers for Terylene?

Benzene-1,4-dicarboxylic acid and ethane-1,2-diol.

Define the Beer-Lambert Law equation.

$A = εlc$, where $A$ is absorbance, $ε$ is molar absorptivity, $l$ is path length, and $c$ is concentration.

What is the formula for the retention value ($R_f$) in chromatography?

$$R_f = \frac{\text{distance moved by spot from base line}}{\text{distance moved by solvent front from base line}}$$

State Raoult's Law.

The partial vapour pressure of a component in a mixture ($p_A$) equals its mole fraction ($x_A$) multiplied by the vapour pressure of the pure component ($p^∘_A$).

What are the raw materials and conditions for the Haber Process?

Nitrogen and hydrogen gas; $450^∘C$, $200\,atm$, and an iron catalyst.