Water

Question 1

Water Structure

Answer 1

Water is made up of two hydrogen atoms covalently bonded to an oxygen atom: H2O

Question 2

Electron sharing in water

Answer 2

Oxygen (due to having a higher electronegativity) attracts the electrons more strongly
Therefore the shared electrons orbit closer to the oxygen resulting in polarity

Question 3

Polarity in water

Answer 3

The oxygen atom is slightly negative (δ–) while the hydrogen atoms are slightly positive (δ+)

Question 4

Dipolarity of water

Answer 4

The dipolarity of a water molecule enables it to form polar associations with other charged molecules

Question 5

Hydrogen bonds

Answer 5

water can form hydrogen bonds with other water molecules

Question 6

Properties of Water

Answer 6

the intermolecular bonding between water molecules gives water distinct properties:
1) Thermal properties
2) Cohesive/ adhesive
3) Solvent properties

Question 7

Thermal Properties

Answer 7

Water has the capacity to absorb significant amounts of heat before changing state due to extensive hydrogen bonding

Question 8

Cohesive and adhesive properties

Answer 8

Cohesion: ability of like molecules to stick together. It allows liquid to resist lowmlevels of external force and high surface of tension
Adhesion: ability of dissimilar Molecules to stick together. it allows attraction to charged polar surfaces and it can therefore flow in opposition of gravitational forces

Question 9

Solvent Properties

Answer 9

Water can dissolve any substance that contains charged particles due to polar attraction if large quantities of water molecules can suffieicently weaken intramolecular forces (such as ionic bonds) and result in the dissociation of the atoms

Question 10

hydrophilic

Answer 10

substances that freely associate and readily dissolve in water. This includes all polar molecules and ions

Question 11

Hydrophobic

Answer 11

Substances that do not freely associate or dissolve in water are characterised as hydrophobic. This includes large, non-polar molecules

Question 12

transport of molecules

Answer 12

The transport of essential molecules within the bloodstream depends on their solubility in water

Question 13

transport in bloodstream

Answer 13

Water soluble substances will usually be able to travel freely in the blood plasma, whereas water insoluble substances cannot

Question 14

Water soluble substances

Answer 14

• Sodium chloride is an ionic compound and can transport within the blood
• oxygen is soluble but just in low amounts (most oxygen is transported by haemoglobin within red blood cells)
• Glucose can be transported freely within blood
• Amino acids will be transported in the blood in an ionised state

Question 15

Water insoluble substances

Answer 15

• Lipids are non polar and hydrophobic and hence will not dissolve in water, instead form complexes with proteins (lipoproteins) to move through the bloodstream
• Hydrophilic portions of proteins will face outwards to shield hydrophobic protein part