U2-T5

Question 1

The main properties of water

Answer 1

1. Change of state
2. Anomalous expansion
3. Solvent properties
4. High heat capacity

Question 2

Water is polar. What does it means?

Answer 2

It means that the positive and negative electrical charges are unevenly distributed

Question 3

Why is water polar ?

Answer 3

Because of the bent shape of the molecule

Question 4

Why a water molecule has is bent shape?

Answer 4

Because the negative charge from oxygen is on a side of the molecule and the positive charge of the hydrogen atoms is on the other side of the molecule. So the reason the shape of the molecule is because of its electronegativity between hydrogen(2.1) and oxygen(3.5)

Question 5

Qu’est éléctronégativité d’un élément?

Answer 5

L’éléctronégativité d’un élément est une grandeur qui caractérise sa capacité à attirer les éléctrons lors de la formation d’un liaison chimique avec un autre élément

Question 6

For most material, the solid form is more heavy or more weak than the liquid form

Answer 6

More heavy, but it is not the case for water

Question 7

What happens when water freezes?

Answer 7

The molecules space one from the other forming a large cristal lattice. There is less particles in an equal volume, this structure is denser and so weaker than in a liquid state

Question 8

Why does ice float?

Answer 8

Because water is denser in its solid form, so in an equal volume of water, there is less molecule in the solid form than in the liquid so it’s weaker and float.

Question 9

What happens to most material when they are warm up and when they are cooled down?

Answer 9

Most material expands when heating and narrows when cooled down. Water react like that between 4 and 100 degrees C

Question 10

What happens to water between 0 and 4 degrees C?

Answer 10

Water expand cooling down under 4 degrees C until 0 degree.

Question 11

What happens to water while cooling down, but above degrees?

Answer 11

Water narrows

Question 12

Why water is also called “general physiological solvent”?

Answer 12

Because most biological reactions occur with solutés dissolved in water

Question 13

What does “high heat capacity” mean?

Answer 13

It means that water heats up and cool down slowly

Question 14

Why is it important (in climate change) that water has a high heating capacity?

Answer 14

Because it helps to maintain climatic stability by moderating temperature changes

Question 15

How often occur hydrogen bonds?

Answer 15

They are ubiquitous

Question 16

Why does hydrogen bonds happen?

Answer 16

This happens because the hydrogen is attracted to both, it’s own oxygen and the oxygen of other molecules that come close enough.

Question 17

What is the total number of hydrogen bonds formed between 1 water molecule ?

Answer 17

It’s 4

Question 18

Water molecules are naturally attracted to one another. How does this affect the biking point of water?

Answer 18

Water molecules tend to bond together in group of 4, acting like a single larger molecule that would normally have a higher boiling point than the small individuals molecules

Question 19

Does pression increase or decrease with altitude?

Answer 19

Decrease

Question 20

Will the boiling point of water be higher or lower at the top of a mountain compared to sea level?

Answer 20

As pressure decreases with altitude, it would be lower in the mountains so the boiling point of water will therefore be lower in mountains

Question 21

What property of water is important when considering how ocean currents affect climate and why?

Answer 21

For ocean currents to affect climate, the water must be able to remain at a stable temperature so it is important that it has a heat capacity

Question 22

What is responsible for driving the hydrological cycle?

Answer 22

Solar energy

Question 23

Named 2 main thyme of energy involved in the hydrological cycle (appart from solar energy)

Answer 23

Kinetic energy and potential energy

Question 24

Which objects posses potential energy

Answer 24

Objects that are not in motion posses potential energy, which is converted to kinetic energy when some force, such as gravity, acts upon the object to sell it in motion

Question 25

When occur the 3 main thyme of energy in hydrological cycle?

Answer 25

Solar energy is responsible for driving the hydrological cycle but once water vapour is in the air, it has potential energy. This is transformed once it Starr’s to fall as precipitation and then flow downwards on and in the ground

Question 26

Formula to find the average transfer rate in or out the reservoir

Answer 26

= volume of water / residence time

Question 27

Can warm or cold ai hold the most water vapour?

Answer 27

Warm air

Question 28

Explain the difference between percolation and infiltration

Answer 28

Infiltration is the movement of surface water down into the ground whereas percolation is the flow of the water down through spaces between soil and rock particles

Question 29

How does groundwater flow helps to recharge aquifers?

Answer 29

Precipitation falls on the ground and infiltrates the soil. It percolates down through the soil and rock and then moves by the groundwater flow through permeable rock to an aquifer

Question 30

Why water evaporates in lakes for exam,e, at less than 100 degrees C?

Answer 30

The hydrogen bonds between water molecules are constantly being broken and reformed, so individual water molecules at the surface can escape and move away. As the temperature of the air above the body water gets warmer, or moist is blown away and dry air takes its place, it can hold more of these escaped molecules, so more water evaporates - even if the temperature of the water is well below boiling point

Question 31

What are the main reservoirs of water?

Answer 31

1. Ocean
2 atmosphere 
3 lakes and rivers
4. Land ice
5. Groundwater
6. Soil
7. Living organisms