Science main points

Major components of air

78% nitrogen

21% oxygen

0.9% noble gases (mainly argon)

0.07% water vapour & others

0.03% carbon dioxide

Oxygen

Glowing/burning splint test

O2 + gas fuel can produce a high temp to cut metals

Help patients w/ breathing difficulties

Carbon dioxide

Limewater/ hydrogencarbonate indicator

X support burning & denser than air → fire extinguisher to put out fires

Dry ice changes to gas at room temperature → produce a fog effect on stage

Nitrogen

No simple tests

Fill up food packages to prevent going bad

Liquid nitrogen can store Iiving cells and tissues

Water vapour/ water

Dry cobalt chloride paper

Argon

Fill up light bulbs

Neon

Fill advertising lights

Helium

Fill up balloons/airships

Photosynthesis formula

6C02 + 6H2O = C6H12O6 + 6O2 (carbon dioxide + water → glucose + oxygen)

Light energy → chemical energy in food

Raw materials → products

Plants only with light and chlorophyll

Testing for starch in green leaves

① Boiling water → kill plant cell

② Alcohol → remove chlorophyll

③ Hot water → make leaf soft & remove alcohol

④ Iodine solution → test for starch

Destarching

Place in dark for at least 48 hours

All starch stored in leaves converts into glucose → used by plant

Purpose: X contain starch when investigation begins

Ensure that starch detect later is formed during the investigation → photosynthesis has taken place

Food chain

Feeding relationship & flow of energy among living things

Respiration

C6 H12 O6 + 6O2 → 6CO2 + 6H2O (glucose and oxygen → carbon dioxide and water)

Cells use oxygen to break down food to release energy in useful forms

(Oxygen is taken into the body thru breathing and carbon dioxide is removed from the body thru breathing)