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AS Biology > Water > Flashcards

Flashcards in Water Deck (23):
1

Why are hydrogen bonds easily formed?

The opposite charges within.

2

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

There are so many.

3

Why is water good as a universal solvent?

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

4

Why do chemical reactions take place more easily in solution?

The dissolved ions can move more freely.

5

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

Cohesion and surface tension

6

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

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

7

Where does surface tension occur and why?

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

8

Why does surface tension occur?

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

9

What is the only liquid with higher surface tension?

Mercury

10

How does surface tension aid transport?

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

11

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

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

12

Why does water have a high specific heat capacity?

Water molecule movement is restricted by the hydrogen bonds

13

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

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

14

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

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

15

Why does water have a high latent hest of vaporisation?

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

16

What is the benefit of water as a coolant?

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.

17

At what temperature is water's max density reached?

4oC

18

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

It floats on the surface

19

What is the benefit of water as a thermal insulator?

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

20

What is the benefit of water's low viscosity?

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

21

What is the benefit of water's transparency?

It enables light to pass through, enabling photosynthesis

22

What is the benefit of water's buoyancy?

It provides support for aquatic organisms, enabling them to live

23

Why is water a dipolar molecule?

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.