1.7 Water

Question 1

Why is water essential

Answer 1

Photosynthesis

Essential for osmosis and diffusion

Good solvent

Question 2

What’s the structure of water

Answer 2

Has 1 oxygen atoms covalent bonded to 2 Hydrogen atoms

Each Hydrogen shares a pair of electrons. With oxygen. Oxygen has greater affinity for electrons than Hydrogen, so it ‘pulls’ electrons closer

This makes oxygen slightly negative and Hydrogen slightly positive

This causes different charged regions making water a polar molecule

Question 3

Role of Hydrogen bonds

Answer 3

Slight negative charge on oxygen atom makes it attract slightly positive Hydrogen atom of another water molecule

Numerous Hydrogen bonds in water make it a very stable structure

Question 4

How are Hydrogen bonds formed

Answer 4

Due to weak electrostatic forces between water molecules leading to Hydrogen bonds to be formed

Each Hydrogen bonds are weak but there are so many that overall effect is large

Question 5

How do you plan for the 8 marker

Answer 5

Point 1 state property
Point 2 what property means
Point 3 apply property to use

Question 6

What does it mean when water has a high specific heat capacity

Answer 6

1. water has a high specific heat capacity
2. This means that it requires a lot of energy to increase its T°C by 1°C
3. This allows for homeostasis and maintenance of human body temp.

Question 7

What does it mean when water has a high latent heat of vaporisation

Answer 7

1. water has a high latent heat of vaporisation
2. Water requires a lot of energy to turn from a solid to a liquid to a gas
3. This is useful in sweating as sweat will require a lot of the body’s heat energy to evaporate meaning that body can cool down

Question 8

What does it mean when water has adhesive and cohesive properties

Answer 8

1. water has adhesive and cohesive properties
2. This means that due to cohesion the water molecules will join to each other because of polarity. It’s adhesive because they are able to stick to other substances
3. This is useful for plants because they can achieve the transpiration pull within xylem

Question 9

Why is water a good solvent

Answer 9

1. Water is a good solvent
2. This is because it allows solutes to dissolve within it
3. This will lead it to be a good transportation solvent within bloodstream and within the xylem

Question 10

Why is water less dense as a solid than a liquid

Answer 10

1. It’s less dense as a solid than a liquid.
2. This means that water as a solid achieves a lattice arrangement whereby molecules are spread wider apart compared to a liquid
3. It helps to produce insulation for aquatic animals below and maintain T°C of water underneath