Water

Question 1

What is water made up of ?

Answer 1

2 Hydrogen atoms and one oxygen

Question 2

What is the charge of a water molecule ?

Answer 2

No over all charge, but the oxygen has a slight negative charge and the hydrogen a slight positive charge

Question 3

Why is water a dipolar molecule ?

Answer 3

The oxygen atom has a slight negative charge, while the hydrogen atoms are slightly positive charge. Therefore water has both negative and positive poles

Question 4

What is the meaning of diplomar?

Answer 4

Has both negative and positive poles

Question 5

What is the attractive force between opposite charges called ?

Answer 5

A hydrogen bond

Question 6

Describe what is a hydrogen bond is

Answer 6

The attractive force between opposite charges

Question 7

How strong is a hydrogen bond?

Answer 7

Relatively weak being about a tenth of the strength of a covalent bond

Question 8

How are water molecules stuck together ?

Answer 8

Hydrogen bonds

Question 9

Why does water have a higher boiling Point than predicted ?

Answer 9

There are huge numbers of hydrogen bonds, so it takes a lot of energy to separate them.

Question 10

What is the specific heat capacity of a substance ?

Answer 10

The amount of energy needed to change the temperature of 1 kg of the substance by 1°.

Question 11

What is the specific heat capacity of water ?

Answer 11

4190jkgC

Question 12

What is latent heat of vaporisation ?

Answer 12

The amount of energy required to evaporate 1 kg of water.

Question 13

What must happen for a substance to change from a liquid to a gas.?

Answer 13

The potential energy stored in the forces between molecules needs to be overcome by the kinetic energy of the motion of particles

Question 14

What is cohesion ?

Answer 14

The tendency of molecules of the same substance to stick together.

Question 15

Why does water have large cohesive forces?

Answer 15

Hydrogen bonding

Question 16

What is surface tension?

Answer 16

When water meets Aircon the water molecules tend to be pulled back into the body of water, rather than escaping it. This force is know as surface tension

Question 17

What does surface tension mean?

Answer 17

The water acts like a skin and a strong enough for a small organisms such as pond skaters to be supported on the water surface

Question 18

Name the reactions where water is used or made

Answer 18

hydrolysis- water us used

condensation- water is made

Question 19

What property of water allows substances to dissolve and move freely for metabolic reactions to take place?

Answer 19

water as a solvent

Question 20

Name the substances water readily dissolves

Answer 20

• respiratory gases
• excretory products
• inorganic ions
• small hydrophilic molecules

Question 21

Explain what property of water keeps the pond skater floating?

Answer 21

Cohesion and surface tension
when water meets air the water tends to be pulled back into the body of water
water acts as a skin

Question 22

How do plants rely on cohesion and surface tension?

Answer 22

Water must be pulled up the xylem tissues