GasesInAtmosphere (combustion/thermal decomposition/greenhousegases)

Question 1

What is the percentage of gases in the atmosphere in descending order

Answer 1

Nitrogen 78%
Oygen 21%
Argon 0.9%
Carbon dioxide 0.04%

Question 2

What are three metals that can be used to test for the presence of oxygen in the air

Answer 2

Copper
Phosphorous
Iron

Question 3

In the experiment using copper to test for the presence of oxygen, why are both syringes pushed back and forth

Answer 3

So that the air in the system keeps passing over the copper

Question 4

In the experiment using copper to test for the presence of oxygen, why is the bunsen burner passed along the tube

Answer 4

To ensure that fresh copper is heated

Question 5

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?

Answer 5

Nitrogen
(because oxygen is used up)

Question 6

Why is it important to use excess metal in experiments testing for the presence of oxygen in the air

Answer 6

To ensure that all of the oxygen is removed

Question 7

John doesnt use excess copper in his experiment to test for the presence of air with oxygen.
Explain why this may be a problem

Answer 7

All of the oxygen may not have reacted, so the percentage of oxygen calculted will be inaccurate and too low

Question 8

Why may it be better to test for the presence of oxygen using copper experiment rather than iron experiment

Answer 8

Because iron experiment is time consuming (takes about a week)

Question 9

How would you measure the total intial volume of oxygen in the experiment using iron to test for the presence of air

Answer 9

Add the volume of oxygen in the gas syringe, the connecting tube and the conical flask

Question 10

Give two reasons why the volume of oxygen collected at the end may not be 21%

Answer 10

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

Question 11

Why is phosphorous a good non-metal to use when testing the presence or oxygen in the air

Answer 11

Because it is very reactive and reacts fast

Question 12

When phosphorous oxide is produced, what does it look like in the bell jar

Answer 12

A white smoke

Question 13

How is the phosphorous heated in the bell jar when the bung is removed

Answer 13

With a hot wire

Question 14

What colour is magnesium oxide

Answer 14

White powder

Question 15

What colour is the flame for burning sulfur

Answer 15

Blue

Question 16

What colour is sulfur

Answer 16

Yellow powder

Question 17

What colour flame does hydrogen oxide burn in

Answer 17

Pale blue

Question 18

What colour flame does magnesium oxide burn in

Answer 18

Bright white flame

Question 19

What colour is magnesium

Answer 19

Silver ribbon

Question 20

What type of reaction is a combustion reaction

Answer 20

An exothermic reaction

Question 21

What compound does magnesium oxide(white powder) form when it reacts with water

Answer 21

Magnesium hydroxide

Question 22

What is the balanced symbol equation with state symbols for the reaction between magnesium oxide and water

Answer 22

MgO (s) + H2O (l) ——-) Mg(OH)2(aq)

Question 23

Write the word equation for when sulfur reacts oxygen

Answer 23

Sulfur + Oxygen ——-) Sulfur dioxide

Question 24

What is produced when sulfur dioxide reacts with water

Answer 24

Sulfurous acid

Question 25

What is the chemical formula for sulfurous acid

Answer 25

H2SO3

Question 26

What is the balanced chemical equation for the reaction between sulfur dioxide and water with state symbols

Answer 26

SO2(g)+ H2O(l) ———) H2SO3 (aq)

Question 27

When any metal oxide is dissolved in water what is formed

Answer 27

A metal hydroxide

Question 28

What are the chemical terms for limestone, quick lime, lime water

Answer 28

Limestone= calcium carbonate Quick lime= calcium oxide Lime water= calcium hydroxide

Question 29

What are four examples of substances that can be thermally decomposed

Answer 29

Copper carbonate Calcium carbonate Petrol(hydrocarbon) Fossil fuels

Question 30

Do all thermal decompsotion reactions produce carbon dioxide?

Answer 30

Yes

Question 31

What is the general word equation for a metal carbonate that is thermally decomposed

Answer 31

Metal carbonate ——-(heat)——-) metal oxide + carbon dioxide

Question 32

What is the balanced symbol equation with state symbols of copper carbonate being thermally decomposed

Answer 32

CuCO3(s)——-) CuO(s) +CO2(g)

Question 33

Describe what you will see when Copper carbonate is thermally decomposed

Answer 33

A colour change from green to black

Question 34

Which carbonate only thermally decomposes at very high temperatures

Answer 34

Calcium Carbonate

Question 35

Which two ways can carbon dioxide be formed

Answer 35

By thermal decomposition of metal carbonates By reacting calcium carbonate with hydrochloride acid By burning fossil fuels

Question 36

What is the definitionnof a green house gas

Answer 36

A gas in the atmosphere that aborbs infrared radiation from the sun and then re radiates it back towards the earth

Question 37

Wrote the balmced wymbol equation for the combustion of hydrogen in the air

Answer 37

2H2+ O2——) 2H2O

Question 38

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?

Answer 38

39.5 Because O x (1-M) =N (Reverse percentages)

Question 39

When measuring the volume of air collected in an experiment, why is it important to allow the gas to cool down first

Answer 39

Because at high temperatures gases expand

Question 40

When calcium carbonate is thermally decomposed, state the appearance of the limewater before the experiment and after

Answer 40

Colourless Cloudy white (precipitate)

Question 41

Explain how sulfur dioxide can change the appearance of a building made of calcium carbonate

Answer 41

Sulfur dioxide reacts with rain water to form sulfurous acid which is rain water and which can corrode the building

Question 42

What is one hse of nitrogen

Answer 42

Used as a refrigerant

Question 43

What is the chemical symbol equation for acid rain

Answer 43

SO2 + H2O ——-) H2SO3

Question 44

What is the physical state of carbon at room temperature

Answer 44

Solid

Question 45

What is the ore of iron called

Answer 45

Haemite

Question 46

What is the word equation for when calcium carbonate reacts with hydrochloric acid

Answer 46

Calcium carbonate + hydrochloric acid ——) calcium chloride + water + carbon dioxide

Question 47

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

Answer 47

1)bung was not put on fast enough so carbon dioxide escaped 2)carbon dioxide dissolved in water

Question 48

What happens when excess carbon dioxide is bubbled through lime water

Answer 48

The precipitate dissolves to form a colourless solution

Question 49

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?

Answer 49

More dense than oxygen