Water

Question 1

Structure
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Answer 1

• Two Hydrogen atoms covalently bonded to one Oxygen
• Oxygen has a small negative charge and Hydrogen has a small positive charge
• Water is a DIPOLE

Question 2

Hydrogen Bonds
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Answer 2

• Formed by the attraction between the slightly negative oxygen atom and the slightly positive hydrogen atom.
• Individually they are very weak
• Many bonds make water molecules very hard to separate

Question 3

Polar Molecule
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Answer 3

• Good solvent
• Good reaction medium
• Good for transport
• Adheres to surfaces

Question 4

Cohesion

Answer 4

Water molecules stick to each other due to hydrogen bonds

Question 5

Adhesion

Answer 5

Water molecules show attraction to other polar molecules

Question 6

High surface tension

Answer 6

Water molecules on surface have a stronger cohesion as they aren’t affected by molecules above

Question 7

High Latent Heat of Vaporisation/Evaporation
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Answer 7

• Lots of energy needed to change water from a liquid to a gas
• Cools down skin as lots of heat energy needed to evaporate sweat

Question 8

High Specific Heat Capacity
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Answer 8

• Lots of energy needed to raise the temperature of 1kg of water by 1℃
• Allows cells to keep stable internal temperature
• Aquatic organisms have a stable environment

Question 9

Universal Solvent
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Answer 9

• Dissolves a wide variety of solutes
• Negative and positive ends of water molecules attract opposing ions, pulling them apart e.g. (NaCl)
• Allows chemical reactions to take place in solution
• Good transport medium for dissolved molecules
• Used as a reactant in chemical reactions e.g. photosynthesis (6CO₂ + 6H₂O = C₆H₁₂O₆ + 6O₂)

Question 10

Density
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Answer 10

• Solid water less dense than liquid water
• Ice floats on top of water
• Maximum density at 4℃
• Ice forms an insulating layer on top of the water, preventing it all from freezing

Question 11

Transparency

Answer 11

Water is transparent, allowing light energy to reach aquatic plants like algae

Question 12

Water as a metabolite

Answer 12

Water is involved in a number of metabolic reactions:

• Hydrolysis
• Photosynthesis
• Aerobic respiration (Condensation reaction)

Question 13

Transport Medium

Answer 13

• Blood plasma is mostly water

- Semen