Chemistry Paper 2

Question 1

How would you test for a haloalkane?

Answer 1

Warm with aqueous NaOH
Add acidified silver nitrate

Question 2

How do you make Tollens’ reagent?

Answer 2

Add aqueous silver nitrate to NaOH. Add aqueous NH3 dropwise until the silver oxide precipitate completely dissolves.

Question 3

What happens when an aldehyde is warmed with Tollens’ reagent?

Answer 3

The aldehyde is oxidised to a carboxylic acid and the silver ions are reduced to silver precipitate

Question 4

How do you name an ester?

Answer 4

Replace -oic acid with oate
Change the -ol to -yl

Question 5

What is the IUPAC name for glycerol?

Answer 5

Propan-1,2,3-triol

Question 6

How is a triglyceride (vegetable oil) made?

Answer 6

1 mol of glycerol and 3 fatty acids (long-chain carboxylics)

Question 7

How is biodiesel made?

Answer 7

A triglyceride is converted to a fatty acid methyl ester using methanol

Question 8

What is hydrolysis?

Answer 8

The opposite of esterification - an ester is broken to form a carboxylic acid and an alcohol

Question 9

Is hydrolysis reversible?

Answer 9

Yes: heating under reflux with dilute acid to form an acid and alcohol
No: heated under reflux with dilute alkalis to form a carboxylate salt and alcohol

Question 10

What is saponification?

Answer 10

The formation of soap by hydrolysing triglycerides in alkaline conditions to glycerol and salts

Question 11

How is benzene converted to cyclohexane?

Answer 11

It is heated with H2 and Ni catalyst

Question 12

What substances can be used to reduce nitrobenzene to phenyl amine?

Answer 12

Fe with HCl
NaOH aq

Question 13

What is the difference between reacting acyl chlorides with ammonia and amines?

Answer 13

Ammonia: white fumes of NH4Cl
Amines: HCl reacts with unreacted amine to form a white ammonium salt

Question 14

How is Nylon 6,6 made?

Answer 14

1,6-hexandioic acid and 1,6-diaminohexane are condensed

Question 15

How is Kevlar made?

Answer 15

1,4-diaminobenzene and 1,4-benzenedicarboxylic acid are condensed

Question 16

What is one advantage of condensation polymers?

Answer 16

Polyesters and polyamides can be broken down into their monomers by hydrolysis (they are biodegradable)

Question 18

What are alpha helices and beta pleated sheets?

Answer 18

-Structures formed due to hydrogen bonds between N and O in the protein chain
-alpha helix: hydrogen bonds form between every fourth peptide bond (the O of C=O and N of C-NH)
-beta pleats: the protein folds in half so the peptides are parallel

Question 19

What are the 4 types of bond between groups of amino acids?

Answer 19

-Hydrogen bonds between R groups
-Disulphide bonds between cysteine amino acids
-Ionic bonds between charged R groups
-Weak hydrophobic interactions between non-polar R groups

Question 20

What are the conditions for the hydrolysis of dipeptide bonds?

Answer 20

-Concentrated HCl
-Boiled

Question 21

How can amino acids be seen on the TLC plate?

Answer 21

-Spraying it with ninhydrin
-UV light

Question 22

What is a nucleotide made of?

Answer 22

A phosphate group, a 2-deoxyribose molecule and a nitrogenous base (A, G, C or T)

Question 23

How many hydrogen bonds are formed between the bases?

Answer 23

-Adenine/Thymine –> 2
-Cytosine/Guanine –> 3

Question 24

How does cisplatin work?

Answer 24

-Water is a better ligand than chlorine
-Hydrogen bonds bind it to the N atoms on the DNA bases
-Water is removed and it forms dative bonds with the nitrogen
-The shape of DNA is distorted and it can’t replicate

Question 25

Which compound is used as the standard when recorded?

Answer 25

Tetramethylsilane
Si(CH3)4

Question 26

Which mechanisms require reflux?

Answer 26

Nucleophilic substitution and
Elimination

Question 27

Which mechanism uses steam and H3PO4 as a catalyst?

Answer 27

Hydration of ethene to an alcohol