去年打的
Air:
Mixture of gases
Oxygen 21%, Carbon dioxide 0.03%, Nitrogen 78%, Noble gases (about 0.9)(inert gases)(un reactive), Water vapour (variable)
Noble gases:
Helium, neon, argon
Airship neon light electric light bulb
P.3
Test for gases:
Oxygen:
Glowing splint (positive result: relights. Negative result: it goes out)
Burning splint (positive result: burns more brightly. Negative result: burns less brightly)
Carbon dioxide:
Hydrogencarbonate indicator [positive result: changes to yellow from red. Negative result: remains red OR changes to purple from red (if there is less than 0.03% of carbon dioxide)]
Lime water (positive result: turns milky from colourless. Negative result: remain colourless.)
Water vapour or water
Dry cobalt chloride paper (positive result: turns to pink from blue. Negative result: remain blue.)
There is no simple test for identifying nitrogen.
Positive and negative result:
Positive result:
If a certain chemical present, the test for it will give us expected result. This expected result is called positive result.
Negative result:
If a chemical is not present, the test will not give the expected result and we get a negative result.
P.4-5
Comparing breathed and unbreathed air
Breathed air contains more carbon dioxide than unbreathed air.
Breathed air contains less oxygen than unbreathed air.
Breathed air contains more water vapour than unbreathed air.
The temperature of breathed air is higher than unbreathed air.
|
Breathed air
|
Unbreathed air
|
|
Oxygen(16%)
Carbon dioxide(4%)
Nitrogen(78%)(no change)
Noble gases(0.9%)
Water vapour(variable)(more than unbreathed air)
|
Oxygen(21%)
Carbon dioxide(0.03%)
Nitrogen(78%)
Noble gases(0.9%)
Water vapour(variable)
|
p.8-11
Burning:
Burning food:
When food burns in oxygen, carbon dioxide and water are formed and energy is given out.
Fuel/food+oxygenàcarbon dioxide+water+energy
Fire triangle:
Temperature, fuel, oxygen
If any side of the triangle is removed, the fire will go out.
To put out fire:
1. Remove the fuel.
2. Cut down the supply of oxygen.
3. Lower the temperature.
Tools:
Cover with plates…
Dry powder or carbon dioxide fire extinguishers.
Fire blanket.
p.12-16
Energy:
We need energy for all body activities.
Food is a source of energy
Energy contents/nutrition facts (in calories)
We use a calorimeter to measure the energy of food.
Food which has high calories is called high-energy food.
P17-21
Photosynthesis:
light
Carbon dioxide + water-----------------à oxygen + food(starch)
Chlorophyll
Iodine solution is test for starch.
Positive result: turns to blue black from brown.
Negative result: remain brown
Displacement of water can collect oxygen because oxygen is insoluble in water.
Destarching
Variegated leavesàchlorophyll is necessary for photosynthesis.
Non-green part: brown
Green part: blue black
Soda lime: absorb carbon dioxide from air
Photosynthesis is important because…
1. It balance the amount of carbon dioxide and oxygen in nature
2. It produce food for all living things. During photosynthesis, light energy from the sun is changed into chemical energy stored as food in the plants. Then plants become food for animals.
(balance the amount of oxygen and carbon dioxide/produce food for other comsumers)
Plants are called producers
Animals feed on plants and other animals are called consumers
Primary consumers, secondary consumers.
This form a food chain.
p.22-33
Gases exchange in animals and plants
Reason of people die in a fire:
Lack of oxygen (suffocate)
The smoke is toxic. There is carbon monoxide.
Burnt by fire
Respiration:
Chemical reaction à new product will form after chemical reaction
Food + oxygenàcarbon dioxide + water + energy(support the activities of the cells)
It same as burning but burning is outside the cell and there is light energy given out.
Respiration has no flame and it’s slow and well controlled.
|
Respiration
|
breathin
|
|
chemical reaction
take place in cells
energy is given out
|
physical process
take place in lungs
movement of air into & out of the lungs
|
Lungs
bronchus  Trachea
air sacs(covered with capillaries)
Treachea, bronchus(bronchi), air sac, capillaries, rib, intercostal muscles, diaphragm
Diffusion
Particales move from a higher cancentration to a lower cancentration,
Breathing mechanism,Chest, volume, pressure, respiratory centre.
|
