GasesInAtmosphere (combustion/thermal decomposition/greenhousegases) Flashcards
What is the percentage of gases in the atmosphere in descending order
Nitrogen 78%
Oygen 21%
Argon 0.9%
Carbon dioxide 0.04%
What are three metals that can be used to test for the presence of oxygen in the air
Copper
Phosphorous
Iron
In the experiment using copper to test for the presence of oxygen, why are both syringes pushed back and forth
So that the air in the system keeps passing over the copper
In the experiment using copper to test for the presence of oxygen, why is the bunsen burner passed along the tube
To ensure that fresh copper is heated
What is the main gas left in the air in the syringes once the experiment to test for the presence of oxygen using copper has finished?
Nitrogen
(because oxygen is used up)
Why is it important to use excess metal in experiments testing for the presence of oxygen in the air
To ensure that all of the oxygen is removed
John doesnt use excess copper in his experiment to test for the presence of air with oxygen.
Explain why this may be a problem
All of the oxygen may not have reacted, so the percentage of oxygen calculted will be inaccurate and too low
Why may it be better to test for the presence of oxygen using copper experiment rather than iron experiment
Because iron experiment is time consuming (takes about a week)
How would you measure the total intial volume of oxygen in the experiment using iron to test for the presence of air
Add the volume of oxygen in the gas syringe, the connecting tube and the conical flask
Give two reasons why the volume of oxygen collected at the end may not be 21%
1- Because the metal may not have been excess so all the oxygen wouldnt have been able to react
2- The experiment wasnt left long enough so there wasnt enough time for all the oxygen to react
Why is phosphorous a good non-metal to use when testing the presence or oxygen in the air
Because it is very reactive and reacts fast
When phosphorous oxide is produced, what does it look like in the bell jar
A white smoke
How is the phosphorous heated in the bell jar when the bung is removed
With a hot wire
What colour is magnesium oxide
White powder
What colour is the flame for burning sulfur
Blue
What colour is sulfur
Yellow powder
What colour flame does hydrogen oxide burn in
Pale blue
What colour flame does magnesium oxide burn in
Bright white flame
What colour is magnesium
Silver ribbon
What type of reaction is a combustion reaction
An exothermic reaction
What compound does magnesium oxide(white powder) form when it reacts with water
Magnesium hydroxide
What is the balanced symbol equation with state symbols for the reaction between magnesium oxide and water
MgO (s) + H2O (l) ——-) Mg(OH)2(aq)
Write the word equation for when sulfur reacts oxygen
Sulfur + Oxygen ——-) Sulfur dioxide
What is produced when sulfur dioxide reacts with water
Sulfurous acid
What is the chemical formula for sulfurous acid
H2SO3
What is the balanced chemical equation for the reaction between sulfur dioxide and water with state symbols
SO2(g)+ H2O(l) ———) H2SO3 (aq)
When any metal oxide is dissolved in water what is formed
A metal hydroxide
What are the chemical terms for limestone, quick lime, lime water
Limestone= calcium carbonate
Quick lime= calcium oxide
Lime water= calcium hydroxide
What are four examples of substances that can be thermally decomposed
Copper carbonate
Calcium carbonate
Petrol(hydrocarbon)
Fossil fuels
Do all thermal decompsotion reactions produce carbon dioxide?
Yes
What is the general word equation for a metal carbonate that is thermally decomposed
Metal carbonate ——-(heat)——-) metal oxide + carbon dioxide
What is the balanced symbol equation with state symbols of copper carbonate being thermally decomposed
CuCO3(s)——-) CuO(s) +CO2(g)
Describe what you will see when Copper carbonate is thermally decomposed
A colour change from green to black
Which carbonate only thermally decomposes at very high temperatures
Calcium Carbonate
Which two ways can carbon dioxide be formed
By thermal decomposition of metal carbonates
By reacting calcium carbonate with hydrochloride acid
By burning fossil fuels
What is the definitionnof a green house gas
A gas in the atmosphere that aborbs infrared radiation from the sun and then re radiates it back towards the earth
Wrote the balmced wymbol equation for the combustion of hydrogen in the air
2H2+ O2——) 2H2O
With the experiment using phosphorous to meausre the concentration of oxygen in the air, there was 50cm^3 of dry ice in the apparatus at the start of the experiment.
How much ice will there be at the end of the experiment?
39.5
Because
O x (1-M) =N
(Reverse percentages)
When measuring the volume of air collected in an experiment, why is it important to allow the gas to cool down first
Because at high temperatures gases expand
When calcium carbonate is thermally decomposed, state the appearance of the limewater before the experiment and after
Colourless
Cloudy white (precipitate)
Explain how sulfur dioxide can change the appearance of a building made of calcium carbonate
Sulfur dioxide reacts with rain water to form sulfurous acid which is rain water and which can corrode the building
What is one hse of nitrogen
Used as a refrigerant
What is the chemical symbol equation for acid rain
SO2 + H2O ——-) H2SO3
What is the physical state of carbon at room temperature
Solid
What is the ore of iron called
Haemite
What is the word equation for when calcium carbonate reacts with hydrochloric acid
Calcium carbonate + hydrochloric acid ——) calcium chloride + water + carbon dioxide
When trying to measure the volume of carbon dioxide obtained from reacting a metal carbonate with acid, state two factors that could affect how the volume of one mole of gases obtained is not 24000cm3
1)bung was not put on fast enough so carbon dioxide escaped
2)carbon dioxide dissolved in water
What happens when excess carbon dioxide is bubbled through lime water
The precipitate dissolves to form a colourless solution
Carbon dioxide does not combust so it is good to use in a fire extinguisher. State another property of carbon dioxide that makes it suitable in a fire extinguisher?
More dense than oxygen
