Oxides, oxygen and water Flashcards
What % does nitrogen form in the atmosphere?
78%
What % does oxygen form in the atmosphere?
21%
What % does argon form in the atmosphere?
0.9
What % does carbon dioxide form in the atmosphere?
0.04%
What fraction does nitrogen form in the atmosphere?
approx. 4/5
What fraction does oxygen form in the atmosphere?
approx. 1/5
What % of water vapour can there be in air?
0%-4%
Describe the experiment to measure the % of O2 in the air using iron wool? (4)
1) Place iron wool at the bottom of a test tube and turn in upside down
2) But it into a beaker with water
3) Mark the water level in the test tube with a rubber band
4) Leave for several days
What will happen to the water level in the iron wool experiment?
It will rise, as the oxygen is being used up, therefore the water gets sucked into the test tube
What is the chemical equation for a iron wool experiment?
4Fe + 3O2 → 2Fe2O3
Describe the experiment to measure the % of O2 in the air using gas syringes? (3)
1) Place copper in a central part
2) Connect gas syringes from both sides
3) Make sure it is air tight
Describe how to carry out the experiment with gas syringes (2)
1) The copper is heated using a bunsen burner
2) The air is pushed backwards and forwards across the gas syringes
How much air does the apparatus contain in the gas syringe experiment?
100 cm3
What is going to happen to copper in the gas syringe experiment?
Copper oxide is going to be formed
What is the equation in the gas syringe experiment?
2Cu + O2 → 2CuO
When the reaction is completed in the gas syringe experiment how much gas will be left?
approx. 79cm3
What is the formula of hydrogen peroxide?
H2O2
How to prepare oxygen in a lab?
Made from hydrogen peroxide using manganese oxide as a catalyst
Write an equation of production of oxygen in a lab with state symbols
2H2O2(aq) using manganese (IV) oxide → 2H2O(l) + O2(g)
Why happens to the catalyst? Where is it written in an equation?
It doesn’t react, therefore it is written above the arrow
What is the test for oxygen?
Glowing splint relights in it
Are metal oxides soluble in water
Insoluble apart from group one metals
What is produced when metal oxides dissolve in water?
Alkali solution
Describe the solubility of Magnesium oxide in water
Slightly soluble
What happens to most non-metal oxides when they are mixed with water?
They produce acidic solutions
Write an equation between water and sulphur dioxide
H2O+SO2 → H2SO3
What happens when carbon dioxide dissolves in water? Formula
It forms carbonic acid H2CO3
What pH does rain water have?
5.6 pH (slightly acidic)
Give an equation explaining the acidity of rain water
CO2+H2O → H2CO3
What acid is usually in an acid rain? +Formula
Sulphuric acid H2SO4
An acid rain is caused when… (2)(+ what acid are they going to form)
water and oxygen in the atmosphere react with:
1) Sulphur dioxide - sulphuric acid
2) Oxides of nitrogen (NOx) - nitric acid
Where do SO2 and NOx mainly come from? (3)
1) Power stations
2) Factories burning fossil fuels
3) Motor vehicles
What are the effects of the acid rain? (3)
1) Reacts with metal and limestone - destroys the buildings and statues
2) Waxy layer of the leaves of trees and make it more difficult for trees to absorb minerals
3) Makes rivers to go acidic, hard for aquatic life to survive
Why acidic water is such a problem for aquatic life?
It decreases the % of oxygen the water can absorb
List ways human uses carbon dioxide (4)
1) Fizzy drinks
2) Fire extinguishers
3) Supercritical fluid extraction
4) Dry ice - stage smoke
Explain how does a fire extinguisher, which uses CO2 work?
CO2 is denser than air and it creates a blanket over the fire. The fire eventually will burn all of O2 and produces CO2, which speeds up the process
What is supercritical fluid extraction used for?
Used to decaffeinate coffee
Greenhouse effect
The rise of temperature the Earth experiences because certain gases in the atmosphere trap energy from the sun
List the greenhouse gasses (3)
1) Water vapour
2) CO2
3) Methane
What will happen without the greenhouse gases
The average Earth’s temperature would be 60C colder
List ways the emission of SO2 and NOx could be decreased (3)
1) Scrubbing (cleaning) the gasses
2) Remove sulphur from fuels
3) Catalyst converter
How does scrubbing help to decrease the emissions from the factories?
Cleans the gasses from power stations and factories to remove SO2 and NOx
How to prepare CO2 in a lab
Made from dilute hydrochloric acid and calcium carbonate
In what product is calcium carbonate present in a lab?
Marble chips
Write the equation of preparing CO2 in a lab
2HCL + CaCO3 → CaCl2 + CO2 +H2O
Test for carbon dioxide
Limewater turns from clear to milky
What is limewater
Calcium hydroxide solution
List properties of CO2 (5)
1) Colourless
2) Odourless
3) Gas at rtp
4) Dense than air
5) Slightly soluble in water
Write the equation of combustion of hydrogen
2H2 + O2→ 2H2O
What form will water be in (combustion of hydrogen)
Initially as water vapour
Test for hydrogen
Place a lighted splint at the mouth of a test tube and there will be a squeaky pop
Test for water
White anhydrous copper (II) sulphate will go blue in the presence of water
Equation for test for water
CuSO4 + 5H2O → CuSO4.5H20
Anhydrous
Without water
What is the problem of the test for water?
It doesn’t show that the water is pure
What is the test for the purity of water?
Boils at 100C and freezes at 0C
