Chemistry Stuff Flashcards
Displacement of metals from their salts
Any metal will displace another below it in the reactivity series from a solution of one of its salts
Hydrogen displacement
Can be displaced from an aqueous solutions
The solution is an acid
Metals above hydrogen in the reactivity series can displace hydrogen gas from dilute hydrochloric/ sulfuric acid
Salts of metals
Chlorides, nitrates, sulfates
Chlorides
Soluble on waer except silver chloride and led (iii) chloride
Nitrates
Soluble in water
Sulfates
Soluble in water
except barium sulfate, calcium sulfate and lead (ii) sulfate
Reduction
Oxygen removed from a metal oxide
Reducing agent
A substance that carries out the reduction
Reduction of a metal oxide
Heating the metal oxide with a more reactive metal
Carbon in reduction
Can reduce some metal oxides into metals
Carbon becomes carbon dioxide
Combustion of hydrogen
Hydrogen burns when heated in air or oxygen
Forms water
Test for hydrogen
Put a lighted splint at the mouth of a test tube, a squeaky pop will be heard if hydrogen is present
Test for water
Add the liquid to anhydrous copper (ii) sulfate
The white powder will turn blue if pure water is present
Copper (ii) sulfate formed
Boils at 100C freezes at 0C
Sacrificial protection of iron
Zinc is more reactive than iron
Even if the iron is scratched the iron is still protected because the zinc reacted and corrodes instead of the iron.
Galvanised iron
Iron coated in zinc
Preventing steel and iron rusting
Can be prevented by preventing contact with water and oxygen
Can be done by orating in: grease, oil, paint, plastic, a less reactive metal
Problems of coating to prevent rusting
Once the coating is scratched/washed away the iron is once again exposed to water and oxygen and will rust
Rusting of iron
Iron+ water+ oxygen
Iron —> iron (iii) due to loss of electrons
Speeding up rusting
By having electrolytes in the water
More reactive the hydrogen metals
React with both: dilute hydrochloric acid and dilute sulfuric acid
Form a salt and hydrogen
magnesium+ HCl / H2SO4
Bubbles
Disappears
Mixture gets hot
Colourless solution formed
Aluminium+ HCl / H2SO4
Bubbles when heated
Disappears
Colourless
Solution formed
Zinc+ HCl / H2SO4
Bubbles
Disappears
Colourless solution formed
Iron+ HCl / H2SO4
Bubbles
Disappears
Pale green solution formed
Presence of carbon dioxide
Limewater turns milky
Carbon dioxide absorbs
infra red
Acid rain
Rain with a below 6 PH
leaches vital vitamin out of the soil- kills trees
Lowers the PH of lakes so that fish can’t live in it
Weathers building made of; limestone, marble, iron
Laboratory preparation of carbon dioxide
Metal carbonate + an acid = carbon dioxide
Calcium carbonate most often used
Laboratory preparation of oxygen
Hydrogen peroxide decomposes slowly and forms water and oxygen
Decomposition sped up by adding the catalyst solid manganese dioxide
Finding oxygen using iron
Place wet iron fillings at the end of a burette
Water rises up the burette
Due to iron reacting with air
Percentage of oxygen =
( volume of oxygen used/volume of air at start ) x 100
Finding oxygen - copper
Aparratus with 100cm^3 of air
Heat copper at one end of the silica tube
Pass air over the copper
Keep heating fresh copper
Stop heating when gas in the servings stops decreasing
Final volume of air left should be 79cm^3
21cm^3 has reacted
Nitrogen in air
78%
Oxygen in air
21%
Argon in air
0.9%
Carbon in air
0.04%
Group 7
Halogens
Non-metals
Poisonous
React with metals and form salts
Three halogens
Chlorine
Bromine
Iodine
Chlorine room temperature
Gas
Green
Bromine room temperature
Liquid
Red-brown
Iodine room temperature
Solid
Black
Group number
Number of electrons in outer shell
Same group
Same chemical properties
Periodic group left to right
Increasing atomic number
Periods
Top to bottom
The more shells
Groups
Group 1
More reactive the further down you go Very reactive metals Stored under oil so they can't react with water/oxygen Alkali metals React with water form alkaline solutions
Group 1 characteristics
Good conductors Very soft Low melting/ boiling points Low densities Shiny surface (dull after reacting with oxygen) Burnt in air/oxygen Form white, solid oxides
Group 8/0
Noble gases
Chemically unreactive
Neither lose or gain electrons easily