Chapter 27- The Atmosphere

Question 1

Experiment to prove:

Oxygen occupies 21% of air (iron)

Answer 1

Upside down graduated cylinder w/ steel wool at the very top
Placed in trough
Iron will react with oxygen sucking water up to 21sm mark on the cyclinder

Question 2

Experiment to prove:

Oxygen is 21% of the atmosphere

Answer 2

One syringe has 100mm^3 of air, one closed

Heat and pass air

Copper turns grey black (now copper oxide)

Air=80cm^3 as oxygen has reacted with the heated copper

Question 3

Experiment to:

Prepare oxygen

Answer 3

• Put hydrogen peroxide in syringe
• Through stopper on beaker with manganese dioxide in it
• They react when released
• Oxygen goes back out stopper, down tube, under beehive shelf and up into a test tube (previously filled with water)

Question 4

Tests for oxygen

Answer 4

1. Colour, smell, pH ———-> colourless, odourless, neutral
2. Glowing split in jar ——–> Ré-lights
3. Burn magnesium ribbon—> burns white light

Question 5

Experiment to:

Prepare carbon dioxide

Answer 5

• Hydrochloric acid dropped from syringe, through stopper
• reacts with calcium carbonate
• Co2 goes up, down tube, under beehive shelf, up test tube

Question 6

Word equation for the preparation of oxygen

Answer 6

Hydrogen peroxide +manganese dioxide —>Oxygen +water

2H2O2+MnO2–> O2 + 2H2O

Question 7

Word equation for the preparation of Co2

Answer 7

HCL + CaCo3 = CO2 + H2O+ CaCl2

Hydrochloric acid + calcium carbonate
=
Carbon dioxide + Water + Calcium Chloride

Question 8

3. Tests to prove Co2

Answer 8

1. Colour, smell, pH ———-> colourless, odourless, acidic
2. Add limewater ————> colour change
3. Pour on candle ———–> extinguishes

Question 9

Equation for limewater and Co2

Answer 9

Calcium hydroxide+Carbon Dioxide->
Calcium Carbonate+Water

Ca(OH)2 + Co2 -> CaCO3 + H2O

Question 10

Uses for Co2

Answer 10

• fire extinguishers
• fizzy drinks
• fridges
• stage effects

Question 11

Nitrogen

Answer 11

78% of air
Unreactive
Condenses at -200°c