2. Inorganic Chem

know the colours formed in flame tests for these cations:

• Li+ is

• Na+ is

• K+ is

• Ca2+ is

• Cu2+ is

• red

• yellow

• lilace

• orange-red

• blue-green

insoluble: carbonates EXCEPT

group 1 and ammonium compounds

insoluble: hydroxides EXCEPT

group 1 hydroxides, calcium hydroxide (slightly soluble)

solubles

• common group 1 and ammonium compounds

• nitrates

• common chlorides (except barium and lead II)

• common sulfates (except barium, calcium, lead II)

test for anions: halogens (precipitates formed) and why is it acidified

Cl–, Br– and I– using acidified (nitric acid) silver nitrate solution

• white

• cream

• yellow

acidified: prevents unreacted hydroxide ions reacting with the silver ions

what is used to test for SO4²-

HCl first, then barium chloride solution

• acid reacts with any carbonate ions present

• white precipitate

test for cations: Cu2+, Fe2+ and Fe3+

by using sodium hydroxide solution:

• blue precipitate

• green precipitate

• brown precipitate

test for anion: CO₃²⁻

Carbonates react with dilute acids to create carbon dioxide.

• This gas can be bubbled through limewater, if the limewater goes cloudy, the gas is CO2

test for anion: (NH₄⁺)

• Add a few drops of sodium hydroxide (NaOH) solution to the sample containing ammonium ions.

• Heat the mixture gently.

• smell/ damp red litmus paper → turn blue

ammonium ion charge

1+

carbonate ion charge

2-

sulfate ion charge

2-

nitrate ion charge

1-

sulfide ion charge

2-

silver ion charge

1+

name: H₂SO₄

sulphuric acid

aluminium ion charge

3+

what donor is an acid

proton (H⁺ ions)

what acceptor is a base

proton

define alkali

Specific type of base that is soluble in water

oxidising agent

• causes oxidation

• gain electrons

• is reduced

• oxidation number decreases

reducing agent

• donates electrons to another element/ion - reduces the other species

• oxidised

barrier methods

protective layer that prevents moisture and oxygen from reaching the iron

• paint

• oil

galvanising

ZINC only

sacrificial protection

more reactive metal to protect iron from rusting (eg magnesium, zinc)

4 most abundant gases in dry air

78% nitrogen, 21% oxygen, 0.9% argon and 0.037% carbon dioxide -

% volume of oxygen using metal

oxygen in air is used up, volume of air decreases about 20% - copper is in excess

% volume of oxygen using non-metal (eg phosphorus)

The phosphorus is lit with a hot wire.

It reacts with the oxygen in the air and causes the water level in the bell jar to rise by about 20%.

presence of water using anhydrous copper(II) sulfate

Anhydrous copper(II) sulfate is white; water = blue

phenophtalein

colorless in acidic solutions

pink in basic solutions

method of metal oxide by REDUCTION

• heated with gas tap (methane)

• light excess gas escaping tube hole

• light bunsen under tube; moving it side to side

• solid: black → rusty brown/ copper

METHANE GAS PASSED OVER SOLID WHILE COOLING

prevent solid getting oxidised back to copper oxide

why is the methane set alight (bright yellow-green)

flammable; prevent accumulation of gas, reducing fire risks

% element in a compound

group 1 melting and boling point trend + why?

melting and boiling points decrease as you go down; number of electron shells increase, atomic radii gets bigger, attraction between nuclei and valence electrons decrease; bonds are weaker, less energy needed to break them

group 7 boiling points trend

• boiling points increase as you go down

• intermolecular forces get stronger

• electron shells increase

• more energy needed to break IMFs