air as a mixture of gases
http://en.wikipedia.org/wiki/Air
Note this is for Dry Air, water vapour can make up typically 1%-4% at surface
.
OC22 show that approximately one fifth of the air is oxygen;
There are many ways of doing this experiment, some are good some are bad. With some the equipment is not cheap, the following method is a reasonably good method and with easy to obtain materials, however the experiment should be left over a weekend, as it does take a little time.
This experiment is based on the fact that rusting requires oxygen
Apparatus
Steel wool, 2 graduated cylinders, a basin and retort stand.
Method
Results
Volume of water poured out = cm3. (1)
100 - Vol of water poured out = cm3 = Volume of steel wool (2)
Air pressure =
Volume of air in upturned graduated cylinder at start = cm3 (3)
(Height of water in tube before - Vol steel wool)
Volume of air in upturned graduated cylinder at end = cm3 (4)
(Height of water in tube after - Vol steel wool)
Difference (3 - 4) = cm3 (5)
Calculations
What is in the cylinder ?? Graduated ???
Total Volume = 100 ml
Vol of Steel Wool = 11
Vol of Water = 8
+ Vol of Air = X
____________
100
Volume of Air in the Beginning ...... =
Vol of Air = 100 - (Vol of Steel Wool + Vol of water)
Volume of Air at the End ...... =
Characteristic test for Carbon Dioxide
To do this we need to find a substance that detects CO2, Such a substance is Limewater, it is clear when it is fresh, it goes Milky in colour when it comes in contact with Carbon Dioxide.
So now we need to get carbon dioxide into the limewater
If you have done the section on Respiration you might have noticed that sucking in did not cause the limewater to go milky, so we will need a more effective method, we could replace our lungs with a suction pump.
An good and simple alternative is to get a pump and to pump air through the lime water.
Characteristic test for Carbon Dioxide
Limewater goes milky in colour when it has CO2 passing through it !
Carbon Dioxide also extinguishes fire !
and is heavier than air !
how much CO2 is in the air .....
CO2 emissions League
Russia 32.9 Tonnes / hd/an
USA 19.5
Australia 18.4
7 France 11.9
8 Germany 10.4
11 UK 9.6
anhydrous copper sulphate
white anhydrous copper sulphate which will turn blue in the presence of water
often the container labelled anhydrous copper sulphate will have gone lightly blue, because air contains water vapour
cobalt chloride!
*Cobalt Chloride is on the banned substance list*
is blue when it is dry
and
pink when it is in the presence of water!
products of combustion of carbon and magnesium
OC25 investigate the ability of oxygen to support combustion in a wooden splint and a candle, and state two uses of oxygen
There is enough oxygen in 2kg of moon dust to keep a human alive for a day!
preparation and properties of carbon dioxide
density of CO2 (qualitative only) acidity of a solution of CO2 in water
Set up the apparatus as shown
By coating all the joins with a petroleum jelly (like vaseline) make sure the system is air tight.
Flood a gas jar with water in and place it with the mouth of the gas jar open above the hole in the beehive shelf.
Slowly drop the HCl on the marble chips.
Observe the reaction in the flask,
Check out the link below for the full description of what happens in the setup to prepare a sample of Carbon Dioxide (CO2) .
Hydrochloric Acid + Marble chips → Calcium Chloride + Water + Carbon Dioxide
Hydrochloric Acid + Calcium Carbonate → Calcium Chloride + Water + Carbon Dioxide
Gas Tests
Place a lit splint in to the gas jar. Write down your observations
The Splint stops burning
Place a glowing splint into the gas jar. Write down your observations
The Splint stops Glowing
Pour some Limewater in the Jar. Write down your observations
The Limewater turns MILKY
Pour the contents onto a lit candle Write down your observations.
The CO2 is denser than air and so flows down putting out the candle
Pour some water into the spent gas jar and test with Litmus papers Write down your observations
Litmus paper turns Blue, indicating a base
The first part of a pneumatic system may not sound like an actual part, the compressed gas itself. There are three main gases used in the construction of a robot pneumatic weapon system; Carbon Dioxide (CO2), Nitrogen (N2), and High Pressure Air (HPA). Nitrogen and HPA can be compressed in a tank to upwards of 5000 psi (pounds per square inch) but require larger tanks. CO2 on the other hand liquefies at around 850 psi which allows it to take up less space and therefore need a smaller tank (The actual pressure is dependant upon outside ambient temperature. The note below will explain why but for the purpose of this help section we'll use 850 psi). CO2 exhibits some really unique properties under pressure and when it is vented. Without going into the theories of thermodynamics let's suffice it to say that as pressure drops so does the temperature and lower temperatures create lower pressures to a point of equilibrium. In other words, a drop in pressure results in a drop in temperature but that same pressure will not come back until the ambient temperature rises back to the same point.
When you let some of the gas out of a CO2 tank (or any pressurized tank for that matter [see below]) the pressure inside the tank drops which makes the tank get cold (REAL cold). Well, now that there isn't as much pressure in the tank the liquid CO2 starts to boil. The boiling CO2 releases gas which increases the pressure until there is enough pressure to keep the liquid from boiling any more, which happens to be around 850 psi. Pretty cool, huh? So as long as you have liquid CO2 in the tank, and it is kept at the same temperature the pressure remains at a relative constant.
An Easy way to prepare CO2 would be to mix some bicarbonate of soda with some vinegar,
Use a funnel to place some vinegar in a small drinks bottle. Over the mouth of the bottle place a balloon with some bicarbonate of soda in the balloon, hold up the balloon, and Observe.
OC28 carry out simple tests on carbon dioxide involving its reaction with limewater (word equation and chemical equation), and with moist litmus paper
Blue Limus
Stayed Blue
Red Litmus
Goes Bluish
UIP
pH = 6
http://www.5min.com/Video/Coal-Combustion-and-Acid-Rain-1354362
Carbon Dioxide is more dense than air
for equal volumes of Air and Carbon Dioxide the Carbon Dioxide would have a greater mass
for equal masses of Air and Carbon Dioxide the Carbon Dioxide would less space
http://www.boconline.ie/pdf_downloads/products/products_by_type/dry_ice_applications.pdf
Helium
http://www.boconline.ie/products/products_by_type/balloon_gas_equipment/index.asp
Test your knowledge at, you will do well
2. Give two uses of oxygen
5. Carbon dioxide is used for
6. Something that changes the rate of a chemical reaction without being used up is a ________________________
7. When water is present cobalt chloride paper turns ________________________
8. The percentage of carbon dioxide in air is __________________
9. The pH of oxygen is ______.
10. The pH of carbon dioxide is _____.
11. Draw a labelled diagram showing how you would show there is water vapour in air. (9)