chemistry topic 9

Question 1

what gasses and in what percentages make up the earths atmosphere

Answer 1

80% N2

20% O2

<1% CO2, H2O + Noble Gases

Question 2

why is Evidence for the early atmosphere of the earth limited

Answer 2

because of the time scale of 4.6
billion years.

Question 3

how has earths atmosphere changed over time

Answer 3

carbon dioxide has decreased:
* dissolved in oceans forms hydrogen carbonates
* ‘locked up’ in sedimentary rocks - forms carbonates
* Taken up by plants during photosynthesis

oxygen has increased because:
* released by plants during photosynthesis

nitrogen has increased because:
* methane/ ammonia reacted with oxygen
* nitrogen is released by bacteria and in decay
* nitrogen builds up due to being unreactive

Question 4

how where oceans formed

Answer 4

volcanic activity released water vapour, nitrogen and CO2. Water vapour condensed to form oceans

Question 5

when did algae first produce oxygen

Answer 5

about 2.7 billion years ago.

Question 6

how is Gas + Oil formed

Answer 6

plankton/tiny marine organisms died Got buried
and subjected to high temperature and pressure over millions of years

Question 7

how is coal produced

Answer 7

Plants / trees absorb carbon dioxide
Plants / trees release oxygen
Plants “trap” carbon when growing
When they die and get buried, turns to coal

Question 8

what increases carbon dioxide

Answer 8

Burning fossil fuels and
deforestation

Question 9

what increases methane

Answer 9

Farming of livestock and landfills

Question 10

how can we be sure that climate change exists

Answer 10

Peer-reviewed evidence shows the temperature of the Earth is increasing resulting in climate change.

Question 11

why is global climate change difficult to model

Answer 11

Global climate change is difficult to model as it is a complex system. This leads to simplified models, speculation and opinions which may be biased.

Question 12

what are the three greenhosue gasses

Answer 12

• Carbon dioxide
• Water vapour
• Methane

Question 13

what do greenhouse gasses do

Answer 13

Greenhouse gases in the atmosphere maintain temperatures on Earth high enough to support life.

Question 14

what leads to global warming

Answer 14

Earth absorbs short length radiation, reradiates it at long wavelength radiation. These are reflected back to Earth heating it up

Question 15

what does climate change lead to

Answer 15

Rising sea levels causing flooding

Droughts

Ice caps melting

Question 16

what is the carbon footprint

Answer 16

The carbon footprint is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of the product, service or event.

Question 17

can can your carbon footprint be reduced

Answer 17

Can be reduced by reducing carbon dioxide and methane emissions

Question 18

what does an Incomplete combustion (lack of oxygen) release

Answer 18

• carbon monoxide - colourless, odourless, toxic – leads to respiratory problem
• soot - carbon particles leads to global dimming

Question 19

what does Complete combustion release

Answer 19

• Carbon dioxide – leads to global warming

Question 20

what chemicals are found in fules

Answer 20

Sulfur and nitrogen

Question 21

what do the chemicals found in flues lead to

Answer 21

sulfur dioxide and oxides of nitrogen – leads to acid rain and respiratory problems

Question 22

how are nitrogen oxides formed

Answer 22

Nitrogen oxides are formed from car engines at high temperatures

Question 23

what do scrubbers do

Answer 23

Scrubbers in power plants can remove SO2/NOx from fumes