2. Chemistry of Water

Question 1

What are the four emergent properties of water?

Answer 1

1. COHESION OF WATER MOLECULES

Cohesion, adhesion, surface tension

2. MODERATION OF TEMPERATURE BY WATER

When atoms / molecules move they have kinetic E -> thermal E

Thermal E transferred as heat - measured in calories - amount of E needed to raise the temp of 1 g of water by 1C

Water - high specific heat - can absorb more heat than most other substances (due to H bonding - extra E needed to break)

Water - high heat of vapourisation - needed more E to vapourise (due to H bonding)

Water controls temperature on the planet

3. FLOATING OF ICE ON LIQUID WATER

Water anomaly - water expands as freezes - forms crystal lattice - uniform space created - less dense - ice floats

Now water freezes from surface - life possible under water

4. WATER - SOLVENT OF LIFE

Good solvent due to polarity - forms aqueous solutions - biological fluids to sustain life

Question 2

How many percent of Earth’s surface covered with water?

Answer 2

75%

Question 3

What does hydrogen bonding provide for water?

Answer 3

Properties: cohesion, adhesion, surface tension, thermal properties, solvent properties, habitat (water anomaly)

Structural order - lay out in tetrahedrons

Question 4

Describe dissociation of water

Answer 4

H₃O⁺ and H⁺ are very reactive - reverse reaction is faster

Question 5

What is an example of a buffer in human blood?

Answer 5

Question 6

Explain ocean acidification

Answer 6

Reduces the availability of carbonate ions for CaCO₃ formation - vital for shells, corals