Gases in the atmosphere

Question 1

Group 1: Describe the reaction of group 1 metals with water

Answer 1

Hydrogen gas produced
metal hydroxide + hydrogen
Called alkali metals because soluble hydroxides are alkali

Question 2

Group 1: State the products when alkali metals react with water
both symbol and word equation

Answer 2

Alkali metal + water -> metal hydroxide
2Li + 2H2O -> H2 + 2LiOH
Lithium + water -> lithium hydroxide + hydrogen

Question 3

Group 1: how does reactivity change as you go down the group?

Answer 3

Gets more reactive

Question 4

Group 7: Know describe the colour and physical state of the group 7 elements

Answer 4

Fluorine - Pale yellow gas
Chorine - Green gas
Bromine - Brown liquid
Iodine - Black solid with purple vapour, solid but sublimates

Question 5

Group 7: How does the reactivity change as you go down the group?

Answer 5

The reactivity decreases as you go down the group because as you go up the group there are less shells - therefore less space between the nucleus and electrons , this means there is less shielding so its easier to attract another electron to complete the outer shell.

Question 6

Group 7: Predict the displacement reactions between the elements in group 7

Answer 6

A more reactive halogen will displace a less reactive halogen
Cl displaces I
F displaces Br
Br displaces I

I /displace Cl
Br /displace Cl
I /displace anything
Cl /displace F

Question 7

Gases in the atmosphere: State the % of volume of 4 gases in the atmosphere

Answer 7

Nitrogen 78%
Oxygen 21%
Argon 0.93%
Carbon dioxide 0.035%

Question 8

Gases in the atmosphere: Describe the experiments which can be used to determine the % volume of oxygen in air

Answer 8

2 syringes with a tube in the middle with copper in.
Heat the copper over a Bunsen burner while pushing on syringes.
The copper would react with the oxygen to form copper oxide turning from brown to black.
The volume in the gas chamber would decrease by 21% because the oxygen has reacted with the copper.
2Cu + O2 -> 2CuO

Question 9

Gases in the atmosphere: State the equation for the reactions of elements with oxygen

Answer 9

E.g.
Magnesium
2Mg + O2 -> MgO
As the two react a bright white light is produced

Hydrogen
2H2 + O2 -> 2H2O
A squeaky pop

Sulphur
2S + 3O2 -> 2SO3
When placed in oxygen the melted sulphur produces a bright blue light.

Question 10

Gases in the atmosphere: Describe the thermal decomposition of metal carbonate

Answer 10

Put metal carbonate in a plugged boiling tube over a Bunsen burner with a tube going to a test tube with lime water in.
When we applied heat to the tube CO2 was produced, this turned the lime water cloudy
The copper carbonate tube contents went black
The copper carbonate decomposed
The carbon dioxide produced turned the lime water cloudy and left copper oxide
CuCO3 -> CO2 + CuO

Question 11

Gases in the atmosphere: What type of gas is carbon dioxide?

Answer 11

A greenhouse gas

Question 12

Reactivity Series: State the reactivity series

Answer 12

Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium 
(Carbon)
Zinc
Iron
Copper
Silver
Gold

Question 13

What is reactivity?

Answer 13

A measure of how readily and violently a substance will react with another substance

Question 14

What is displacement?

Answer 14

When a more reactive metal takes the place of another one in a compound

Question 15

State the conditions under which iron rusts

Answer 15

Water
Oxygen
They rust faster in salty water or acid rain.

Question 16

How do you prevent iron from rusting?

Answer 16

Barrier method – The technique of coating an iron object to prevent oxygen or water reaching the surface, this prevents rust
Galvanising – The iron of steel object is coated in a layer of zinc. Zinc is more reactive than iron so it oxidises in preference to the iron object
Sacrificial protection – this is where a layer of more reactive metal coats the iron to lose electrons instead of the iron. Magnesium and Zinc are often used

Question 17

What is reduction?

Answer 17

Loss of oxygen or gain of electrons

Question 18

What is oxidation?

Answer 18

Gain of oxygen or loss of electrons

Question 19

What is redox?

Answer 19

A reaction where oxidation and reduction occurs

Question 20

What are most metals extracted from?

Answer 20

Ores- a rock containing enough metal to make it economic to extract

Question 21

How are unreactive elements found?

Answer 21

As elements (native)- unreactive metals found as elements in nature

Question 22

How is a metal extracted?

Answer 22

Linked to its position on the reactivity series relative to carbon

Question 23

How do you extract iron?

Answer 23

Iron ore, coke and limestone are fed into the top of the blast furnace
Hot air is blasted up the furnace from the bottom
Oxygen from the air reacts with coke to form carbon dioxide
Carbon dioxide reacts with more coke to form carbon monoxide
Carbon monoxide is a reducing agent. Iron (iii) oxide is reduced to iron
Dense molten iron runs to the bottom of the furnace and is run off
Limestone is broken down by heat to calcium oxide
Calcium oxide reacts with impurities like sand to form a liquid called slag
The slag falls to the bottom and is tapped off.

Question 24

State the symbol equations in order for the process of extracting iron

Answer 24

Coke + Oxygen = carbon dioxide
C + O2 -> CO2
Carbon dioxide + coke = Carbon dioxide
CO2 + C -> 2CO
Iron ore + carbon monoxide = Iron + carbon dioxide 
Fe2O3 + 3CO -> 2Fe + 3CO2
Limestone = calcium oxide + carbon dioxide
2CaCO3 -> 2CaO + 2CO2
Calcium oxide + sand = Slag
CaO + SiO2 -> CaSiO3