2.2 Water

Question 1

What is a hydrogen bond?

Answer 1

Intermolecular force between mocs. Hydrogen bonds give water it’s unique properties.

Question 2

What are the cohesive properties of water?

Answer 2

Cohesive properties: binding of like mocs. Ex. 2 water mocs. Important for water transport in plants -> water pulled up through xylem vessels.

Question 3

What are the adhesive properties of water?

Answer 3

Adhesive properties: binding of unlike mocs. by H bonds. Ex. Water adheres to walls of xylem vessels in plants to not fall down due to gravity.

Question 4

What are the thermal properties of water?

Answer 4

High specific heat capacity: amount of energy required to raise the temperature of water is high due to H bonds.
High latent heat of vaporization: heat energy required to evaporate water is relatively high, so it has a cooling effect (evaporative coolant -> sweat)
High boiling point

Question 5

What are the solvent properties of water?

Answer 5

Polar nature of water means that it forms shells around other polar mocs. which dissolves them and keeps them in solution.
E.g. Cytoplasm

Question 6

What happens to ionic and covalent mocs in water?

Answer 6

Ionic mocs. : Dissociate (separate into ions)
Polar covalent : dissolve (Mocs stay together and bond w water)
Non polar covalent : does not dissolve (repels and forms layer)

Question 7

What are hydrophilic and hydrophobic substances?

Answer 7

Hydrophilic: chemically attracted to water (all substances that dissolve, polar and ions, substances that what’re adheres to)
Hydrophobic: non polar, not attracted to water (non polar can dissolve in other non polar substances)

Question 8

What makes water have a polar covalent bond?

Answer 8

Unequal sharing of electrons between O and 2 H. H atoms slightly positive and O atom slightly negative.