Gases in the atmosphere Flashcards
Group 1: Describe the reaction of group 1 metals with water
Hydrogen gas produced
metal hydroxide + hydrogen
Called alkali metals because soluble hydroxides are alkali
Group 1: State the products when alkali metals react with water
both symbol and word equation
Alkali metal + water -> metal hydroxide
2Li + 2H2O -> H2 + 2LiOH
Lithium + water -> lithium hydroxide + hydrogen
Group 1: how does reactivity change as you go down the group?
Gets more reactive
Group 7: Know describe the colour and physical state of the group 7 elements
Fluorine - Pale yellow gas
Chorine - Green gas
Bromine - Brown liquid
Iodine - Black solid with purple vapour, solid but sublimates
Group 7: How does the reactivity change as you go down the group?
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.
Group 7: Predict the displacement reactions between the elements in group 7
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
Gases in the atmosphere: State the % of volume of 4 gases in the atmosphere
Nitrogen 78%
Oxygen 21%
Argon 0.93%
Carbon dioxide 0.035%
Gases in the atmosphere: Describe the experiments which can be used to determine the % volume of oxygen in air
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
Gases in the atmosphere: State the equation for the reactions of elements with oxygen
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.
Gases in the atmosphere: Describe the thermal decomposition of metal carbonate
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
Gases in the atmosphere: What type of gas is carbon dioxide?
A greenhouse gas
Reactivity Series: State the reactivity series
Potassium Sodium Lithium Calcium Magnesium Aluminium (Carbon) Zinc Iron Copper Silver Gold
What is reactivity?
A measure of how readily and violently a substance will react with another substance
What is displacement?
When a more reactive metal takes the place of another one in a compound
State the conditions under which iron rusts
Water
Oxygen
They rust faster in salty water or acid rain.
How do you prevent iron from rusting?
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
What is reduction?
Loss of oxygen or gain of electrons
What is oxidation?
Gain of oxygen or loss of electrons
What is redox?
A reaction where oxidation and reduction occurs
What are most metals extracted from?
Ores- a rock containing enough metal to make it economic to extract
How are unreactive elements found?
As elements (native)- unreactive metals found as elements in nature
How is a metal extracted?
Linked to its position on the reactivity series relative to carbon
How do you extract iron?
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.
State the symbol equations in order for the process of extracting iron
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