probs need to know

Question 1

Define First Ionisation Energy

Answer 1

It’s how much energy it takes to remove the first electron from an atom in the gas phase.

Question 2

Boiling point of nh3 compared to chloromethane

Answer 2

Ammonia has a higher boiling point than chloromethane because it has hydrogen bonding, which is stronger than the dipole-dipole forces in chloromethane.

Question 3

How to draw three monomers of propene + hydrochloric acid

Question 4

Difference between alkane and alkene

Answer 4

Alkanes are saturated hydrocarbons with only single bonds between carbons whereas alkenes are unsaturated hydrocarbons with at least one double bond between carbons atoms \

Question 5

How to draw ester of compound

Answer 5

Ester is when carboxylic acid and alcohol react > functional group is -coo-
Whataver carbon is connected to the double bonded oxygen becomes part of the main chain e.g ethanoate

Question 6

Benzene 1,4 diol

Question 7

Ethene 1,2 diol

Question 8

What are two advantages of using a biofuel over a petrofuel?

Answer 8

-Biofuel = renewable source = sustainable into the future
-Biofuels > lower net green house gas emmisions

Question 9

What is density?

Answer 9

How tightly packed things are together

Question 10

How does branching affect density of polymers?

Answer 10

If polymers are straight with no branching, they can pack closer together therefore have a high density.
Whereas, if they are branched they can’t pack as closely together therefore they have a lower density

Question 11

How does flexibility and branching work and why?

Answer 11

If a polymer has lots of branches, the chains:

Can’t lie close together

Can slide past each other more easily

So:
More branching = more flexible
Less branching = stiffer

Question 12

What is crosslinking and what does it mean?

Answer 12

Crosslinking is when polymer chains are connected together with chemical bonds, like bridges.

Effect:

Chains can’t move freely

Makes the material hard, strong, and rigid

Can’t be melted or reshaped

Example: Thermosetting plastics have crosslinks.

Question 13

What even is addition polymerization?

Answer 13

Addition polymerisation is when:

You start with alkenes (with double bonds)

The double bonds open up

They join together into one big chain (polymer)

No other product is made — just the polymer.
This is different from condensation polymerisation, which gives water or another small molecule as a by-product.

Question 14

What is condensation polymerisation?

Answer 14

Condensation polymerisation is when:

Two different monomers join together

Each time they join, they release a small molecule (usually water)

📌 It’s like clicking two Lego blocks together and a droplet of water pops off each time.

Example small molecule lost: H₂O (water)

Common monomers:

One with –OH (alcohol) groups

One with –COOH (carboxylic acid) or –NH₂ (amine) groups

Question 15

What are polyesters?

Answer 15

Polyesters are a type of polymer made by condensation polymerisation between:

A diol (molecule with 2 –OH groups)

A dicarboxylic acid (molecule with 2 –COOH groups)

Each time they join, they lose water and form an ester link.

Question 16

What are elastomers?

Answer 16

Elastomers are stretchy polymers — like rubber bands.

The polymer chains are loosely crosslinked

When you stretch them, the chains uncoil and slide

When you let go, they snap back to shape

✅ Used for: rubber, elastic bands, tyres, gloves

Question 17

What is a high density polyethene?

Answer 17

It’s a thermmoplastic polymer , minimal branching therefore high density, plastic bottles, durable and can withstand pressure

Question 18

What are low density polyethene?

Answer 18

It’s a thermoplastic polymer, flexibility, softness, and ability to be easily heat-sealed. Common examples include plastic bags (grocery, bread, frozen food), food containers, squeezable bottles, and various wraps and films.

Question 19

What is the difference between low and high density polyethenes?

Answer 19

LDPE has more branching in its structure, making it more flexible, soft, and transparent. HDPE, on the other hand, has a more linear structure, making it harder, more rigid, and more resistant to chemicals and temperature

Question 20

What effect does branching have on a molecules density?

Answer 20

It makes it less dense because can’t pack as close together

Question 21

Explain the synthesis of primary amine

Answer 21

haloalkane + ammonia > primary amine + hydrohallide

Question 22

What are polymers often referred to as?

Answer 22

Plastics

Question 23

What is a polyamide?

Answer 23

A polyamide is a polymer with repeating units linked by amide bonds.

Question 24

What actually is gravimetric analysis?

Answer 24

Gravimetric analysis is a method used to determine the concentration of a substance by turning it into a solid (precipitate), then filtering, drying, and weighing it.

Example: To find the amount of sulfate in a solution, you might add a solution of barium chloride. This forms barium sulfate (BaSO₄), which is a white precipitate:
You filter the precipitate.

Dry it to constant mass.

Weigh it.

Use stoichiometry to calculate how much sulfate was in the original solution

Question 25

What are some problems that could occur and some improvements?

Answer 25

A possible problem is that the precipitate may not have been fully dried, which would result in a higher measured mass and inaccurate concentration. ✅ This can be improved by reheating and reweighing the precipitate until a constant mass is achieved.