Section 4-Inorganic Chemistry P1 (pg35-40, pg51-53) Flashcards
What is produced when group 1 elements react with oxygen?
What are some examples?
- form metal oxides (this is why metals tarnish when left in the air- a dull metal oxide layer has formed)
- Lithium->lithium oxide(Li₂O)
- Sodium->sodium oxide(Na₂O) and sodium peroxide(Na₂O₂)
- Potassium->potassium peroxide(K₂O₂) and potassium superoxide(KO₂)
What is produced in the reaction between group 1 elements and water?
- they all react vigorously
- the reaction produces a metal hydroxide and the solution is alkaline(hence they are called the alkali metals)
- the reaction also produces hydrogen (hence the fizzing)
What happens to the reactivity of Group 1 as you move down the group?
- Group 1 elements become more reactive as you go down the group
- This is visible with their reactions with water: lithium takes the longest to react where as potassium takes the smallest amount of time, this trend is also visible with their reactions with oxygen
What is the general trend as you go down the halogens?
- the elements have a darker colour
- have a higher boiling point
- reactivity decreases
What are the properties of Chlorine (Cl₂)?
- green gas
- boiling point -34°C
What are the properties of Bromine (Br₂)?
- red-brown liquid
- boiling point 59°C
What are the properties of Iodine (I₂)?
- dark grey solid
- boiling point 185°C
What reactions go on with the halogens?
Displacement reactions- more reactive halogens will displace less reactive ones
What happens when Potassium chloride (colourless solution) is added to:
1) Chlorine water(colourless)
2) Bromine water(orange)
3) Iodine water(brown)
1) no reaction
2) no reaction
3) no reaction
What happens when Potassium bromide (colourless solution) is added to:
1) Chlorine water(colourless)
2) Bromine water(orange)
3) Iodine water(brown)
1) orange solution formed(because the bromine has been displaced by the chlorine)
2) no reaction
3) no reaction
What happens when Potassium iodide (colourless solution) is added to:
1) Chlorine water(colourless)
2) Bromine water(orange)
3) Iodine water(brown)
1) brown solution formed(because the iodine has been displaced by the chlorine)
2) brown solution formed(because the iodine has been displaced by the bromine)
3) no reaction
What do halogen displacement reactions involve?
Halogen displacement reactions involve the transfer of electrons. REDOX REACTIONS(oxidation and reduction happen simultaneously)
Define Oxidation:
Loss of electrons
Define Reduction:
Gain of electrons
What is OIL RIG?
O - oxidation
I - is
L - loss
R - reduction
I - is
G - gain
What main gases are in the atmosphere and what is the percentage composition?
Nitrogen - 78%
Oxygen - 21%
Argon - nearly 1%
Carbon Dioxide - 0.04%
What different ways can you test the amount of oxygen in the air?
- IRON reacting with the air(will form rust)
- PHOSPHORUS reacting with the air(phosphorus will react with oxygen in the air to make phosphorus oxide)
- COPPER reacting with the air(will react to form copper oxide)
- FLOATING CANDLE(the candle will burn and use the oxygen in the air)
Describe how iron wool (metal) can be used to work out how much oxygen there is in the air:
- soak some iron wool in acetic acid(acid will catalyse the reaction), push the wool into a measuring cylinder, invert the measuring cylinder into a beaker of water
- record the starting position of the beaker water level in the measuring cylinder
- over time the water level in the measuring cylinder will rise(because the iron reacts with the oxygen and the water rises to fill the space the oxygen took up)
- leave until the water level stops changing and then record the finishing position of the water in the measuring cylinder
- then find the change in volume and divide it by the starting volume and times by 100
Describe how phosphorus can be used to determine the percentage of oxygen in the air:
- place the phosphorus in a tube and attach a glass syringe at either end with 100cm³ air in one syringe and the other empty
- heat the phosphorus and use the syringes to pass the air over the phosphorus(forming phosphorus oxide)
- keep on sending air across it until the volume doesn’t change then do 100 - your starting volume to find out the percentage of oxygen in the air
When you burn something what does it react with?
When you burn something it reacts with OXYGEN in the air
-this forms an oxide (it can be acidic or basic)
What happens when you burn magnesium?
- burns with a bright white flame
- white power is formed(magnesium oxide)
- magnesium oxide is slightly alkaline when dissolved in water
What happens when you burn hydrogen?
- burns very easily with oxygen(can be explosive)
- has an orangey/yellow
- water is produced
- often used as a test for hydrogen gas