Properties of Water

Question 1

How is a water molecule bonded

Answer 1

Covalently

Question 2

Why does water form hydrogen bonds?

Answer 2

• Contains dipoles
• Between δ- O and δ+ H
• Making it a polar molecule

Question 3

What properties does water have because of Hydrogen Bonding?

Answer 3

• Solvent
• High specific heat capacity
• High specific latent heat
• Cohesive
• Less dense as a solid
• Reagent

Question 4

How does water work as a solvent?

Answer 4

• Polar
• So ions and covalently bonded polar substances (glucose) can dissolve in it
• Chemical reactions can therefore occur easier (dissolved solutes more free to move around so are more chemically reactive)
• Metabolites can be transported efficiently (except for non polar ones because they are hydrophobic)

Question 5

What is specific heat capacity? What is water’s specific heat capacity?

Answer 5

Amount of energy required to raise the temperature of 1Kg of a substance by 1°C

4200 J/Kg°C

Question 6

Why does water have such a high specific heat capacity?

Answer 6

Because there are lots of hydrogen bonds so takes a a lot of energy to break these bonds and a lot of energy to build them.

Question 7

Advantages of Water having a high Specific Heat Capacity

Answer 7

• Temp of water doesn’t fluctuate much
• Can provide a suitable habitat

OPTIMAL TEMPERATURE MAINTAIND WITHIN CELLS AND THE BODY

• Temperatures remain fairly constant which is important for optimal enzyme activity
• Water in blood plasma transfers heat around body
• In warmer regions, more blood passes through, and heat energy is absorbed by water to cool these areas of the body, while the temp of the water doesn’t fluctuate much

Question 8

What is specific latent heat?

Answer 8

Amount of energy required to change state of 1kg of a substance without a change in temperature

Question 9

How is a high latent heat in water useful?

Answer 9

• Lots of energy required to evaporate water to water vapour
• So little water is required to evaporate for organism to lose a great amount of heat energy
• So sweating in skin or transpiration in leaves gives a COOLING EFFECT

Question 10

How is water’s adhesive and cohesive properties useful?

Answer 10

• Caused by hydrogen bonds
• Columns of water can move up xylem or through vessels in animals
• Surface tension, so pond skippers can exist
• Water forms hydrogen bonds with other molecules (adhesion) like cellulose, enabling transpiration up xylem to occur