Water - Opportunities

Question 1

What is the volume of water circulation globally each year?

Answer 1

577,000 km3

Question 2

What is the total amount of salt water on earth?

Answer 2

1.365 billion km3

Question 3

What is the total amount of fresh water on earth?

Answer 3

35 million km3

Question 4

What the amount of usable fresh water on earth?

Answer 4

200,000 km3

Question 5

What is the kind of water that is mainly usable?

Answer 5

Groundwater

Question 6

What percent of the total water on earth can be readily consumed?

Answer 6

0.01%

Question 7

What percent of the world population will live in areas of water stress by 2025?

Answer 7

40%

Question 8

Why are developing countries most impacted by water scarcity?

Answer 8

Lack infrastructure for treatment, sanitation and transport of water

Question 9

Globally, is more water available or or accessible? Why?

Answer 9

There is more available but it is not utilised as most of this accessible water is in developing countries which lack infrastructure

Question 10

What is the general definition of water stress and water scarcity?

Answer 10

Insufficient available water to meet demands either due to low volumes or poor quality

Question 11

What is the largest use of water globally?

Answer 11

Agriculture

Question 12

Define water withdrawal/extraction

Answer 12

The water removed from a source

Question 13

Define water consumption

Answer 13

Water that has been incorporated into a products, evaporated or contaminated so that it cannot be discharged or reused

Question 14

howe much water extracted extracted is wasted before it is consumed?

Answer 14

15%

Question 15

What is virtual water use? How is it used in these circumstances?

Answer 15

• The water used in the production of an item (e.g. agriculture, manufacturing and industry uses a lot of water for items where you don’t actually consume water)
• Used either directly (i.e. put on crops) or indirectly (i.e. to make diesel used to power vehicles)

Question 16

How is water usage proportional to wealth?

Answer 16

Increasing affluence, consumption of food and goods are related to increased water usage

Question 17

What is water used for in processing industries?

Answer 17

Cooling, steam, cleaning, solvent, ingredients

Question 18

What are the unique properties of water?

Answer 18

• High cohesion/surface tension
• High heat capacity
• Power solvent of polar + ionic substances
• Solid is less dense that its liquid
• High heat of vaporisation

Question 19

What do all of waters unique properties stem from?

Answer 19

Their hydrogen bonds

Question 20

What is the molecular structure of water (including bonds etc)?

Answer 20

H and O atoms are covalently bonded where two H’s bond to 1 O

Question 21

How is the hydrogen bonding created?

Answer 21

The O atoms have stronger attraction for the electrons due to O’s stronger electronegativity creating large dipoles

Question 22

At any instant at 37˚C how many H2O bonds are created?

Answer 22

15% of H2O molecules are bonded to four partner molecules

Question 23

Define cohesion

Answer 23

The property of similar molecules being attracted to each other

Question 24

Define Adhesion

Answer 24

Property of different molecules being attracted to each other

Question 25

Is water cohesive or adhesive? Why?

Answer 25

It is both as the strong dipoles create strong intermolecular attractions between other dipoles of water and other substances

Question 26

What is an example of waters cohesive natures?

Answer 26

A meniscus forms on thin tubes as the water is attracted to the sides

Question 27

What property of water does the cohesion of water form?

Answer 27

Surface tension

Question 28

What is a practical significance of surface tension?

Answer 28

Creates a surface film which makes it harder for an object to moe through the surface that move in the water

Question 29

What is heat capacity?

Answer 29

The quantity of heat energy require to raise the temperature of one gram of substance by one degree C

Question 30

How does waters high heat capacity influence its properties?

Answer 30

It absorbs large amount of heat without large amount of temp change

Question 31

How do the large bodies of water (e.g. oceans, lakes…) stabilise the earths air temp? How does this impact life on earth?

Answer 31

• During the day it absorbs heat and during the night it releases it
• maintain the temperature more consistently within the parameter of life + enables organisms (which are mainly made of water) to resist temp changes better

Question 32

What happens as liquid evaporates? Why?

Answer 32

• The surface it leaves cools down

- The highest energy particles leave reducing the heat energy of the substance

Question 33

How does water dissolve polar/ionic substances?

Answer 33

Water molecules surround other charged molecules with a hydration shell in a price called solvation

Question 34

What are some benefits and disadvantages of the solvent properties of water?

Answer 34

Benefit: enables biological fluids to transport materials easily (e.g. blood, plant sap…)
Disadvantage: Polluting substances easily dissolve/disperse and are hard to remove + harmful microorganisms thrive in water

Question 35

Why is ice (solid) less dense than water (liquid)?

Answer 35

Ices consists of highly ordered structure with four hydrogen bonds per molecules creating large hexagonal holes decreasing the density

Question 36

Many different crystalline structures in ice are know to form? What causes the different structure?

Answer 36

14 so far from varying pressure and temp conditions

Question 37

How does the property of ice being less dense than water benefit life on earth?

Answer 37

Creates an insulating layer on top of water preventing it from freezing enabling life to survive in cold water conditions

Question 38

What happens when living tissue freezes? Why? how can this be reduced?

Answer 38

• Ice crystals form inside cells and rupture the cell
• Ice expands when it freezes
• By freezing water faster it gives less time for ice to form ice crystals so they are smaller therefore less damage on cells

Question 39

What is a unique property of ice that can is shown on a phase diagram? What does this show?

Answer 39

Solid/liquid slope on phase diagram has a negative gradient showing that as the pressure increases the melting point decreases (normally increasing pressure = increasing melting point FYI)