Oxygen and oxides.

Question 1

Gases in air w/ percentages.

Answer 1

Nitrogen-78%
Oxygen-16%
Argon-1%
CO2-0.04%

Question 2

How can copper be used to show the amount of oxygen in the air?

Answer 2

Copper is put in a large tube that is attached to 2 gas syringes.
1 contain 100cm3 of air, 1 is empty.
Copper is heated strongly.
Air is passed over the copper using syringes.
Oxygen reacts with copper, volume of air = about 84cm3 after the experiment.

Question 3

How can iron be used to show the percentage of oxygen in the air?

Answer 3

Iron filing are placed in a burette full of air, one end of the burette is placed in water.
Iron reacts with oxygen, water moves into the burette.

Question 4

How can phosphorus be used to show the percentage of oxygen in the air?

Answer 4

Phosphorus placed on a tray inside a tube full of air
Tube is placed in a beaker of water
Phosphorus reacts with oxygen in the air and use up oxygen
Volume of air decreases
Water moves into tube
Phosphorus moves up the tube.

Question 5

How can oxygen gas be prepared in a lab?

Answer 5

Decomposition of hydrogen peroxide
H202====> oxygen +water
Manganese oxide (IV) catalyst
Oxygen is collected over water.

Question 6

What happens when magnesium reacts with oxygen?

Answer 6

Burns- bright white flame
White solid
2Mg+O2===> 2MgO
UI goes blue in MGO

Question 7

What happens when carbon reacts with oxygen?

Answer 7

Orange flame
Colourless gas
C+O2===> CO2
UI goes orange in CO2

Question 8

What happens when sulfur reacts with oxygen?

Answer 8

Burns
Colourless gas
2S+ O2===> 2SO
UI goes red in SO