Water

Question 1

Why are hydrogen bonds easily formed?

Answer 1

The opposite charges within.

Question 2

Why is water a very stable structure, despite hydrogen bonds’ weakness?

Answer 2

There are so many.

Question 3

Why is water good as a universal solvent?

Answer 3

As it is dipolar, it can dissolve more charged/polar molecules.

Question 4

Why do chemical reactions take place more easily in solution?

Answer 4

The dissolved ions can move more freely.

Question 5

What are water’s other two properties (beyond being a solvent) that makes it good for transport?

Answer 5

Cohesion and surface tension

Question 6

Cohesion prevents long chain water molecules from breaking, what is the effect of this?

Answer 6

The chains can be drawn up xylem vessels to the tops of the tallest trees.

Question 7

Where does surface tension occur and why?

Answer 7

The water-air interface, due to hydrogen bonding between water molecules

Question 8

Why does surface tension occur?

Answer 8

Water molecules bond with each other, but not with molecules in there. The uneven distribution caused leads to surface tension

Question 9

What is the only liquid with higher surface tension?

Answer 9

Mercury

Question 10

How does surface tension aid transport?

Answer 10

The surface forms a skin which can provide a habitat for aquatic life like pond skaters.

Question 11

Water has a high specific heat capacity. What is specific heat capacity?

Answer 11

The energy needed to raise 1g of a compound’s temperature by 1oC.

Question 12

Why does water have a high specific heat capacity?

Answer 12

Water molecule movement is restricted by the hydrogen bonds

Question 13

What are the two benefits of water as a temperature stabiliser?

Answer 13

•High specific heat capacity.

• aquatic habitats have relatively stable temperatures.
• it ensures a constant internal environment inside cells for enzyme controlled processes.

Question 14

Water has a high latent heat of vaporisation. What is this?

Answer 14

The heat energy needed to change water from a liquid to a vapour state (evaporate).

Question 15

Why does water have a high latent hest of vaporisation?

Answer 15

The many hydrogen bonds need a lot of heat to break.

Question 16

What is the benefit of water as a coolant?

Answer 16

High latent heat of vaporisation. It helps with temperature control. When it vaporises, it uses heat from the surface it is on. This cools the surface, lowering body temp.

Question 17

At what temperature is water’s max density reached?

Answer 17

4oC

Question 18

What is the effect of ice being less dense than water?

Answer 18

It floats on the surface

Question 19

What is the benefit of water as a thermal insulator?

Answer 19

The ice forms an insulator layer, preventing the water underneath from freezing and protecting the aquatic life underneath.

Question 20

What is the benefit of water’s low viscosity?

Answer 20

Its molecules flow past each other easily, making it work as a lubricant. E.g. Mucus

Question 21

What is the benefit of water’s transparency?

Answer 21

It enables light to pass through, enabling photosynthesis

Question 22

What is the benefit of water’s buoyancy?

Answer 22

It provides support for aquatic organisms, enabling them to live

Question 23

Why is water a dipolar molecule?

Answer 23

Oxygen has a greater affinity for electrons than the the hydrogen, pulling the electrons closer. This creates differently charged regions as the oxygen is slightly negative and the hydrogen is slightly positive.