inorganic chemistry - acids, bases, salt prep

describe a neutralisation reaction in terms of proton transfer

neutralisation reaction - proton is transferred from acid to base

which are the spectator ions (for neutralisation reaction)

what is the ionic formula

_____, ______ and _____ compounds are soluble

sodium, potassium, ammonium

all _______ compounds are soluble

nitrates

chloride compounds are ____ except with _______ and _____

chloride compounds are SOLUBLE, except with

silver and lead (II)

sulfate compounds are _______ except with ______ ________ _______

soluble, except with

barium, calcium, lead

carbonate compounds are _____ except with ____ _____ _____

carbonate compounds are INSOLUBLE

except with sodium, potassium, ammonium

hydroxide compounds are _______ except with ___x3

hydroxide compounds are INSOLUBLE except with

sodium, potassium, ammonium

what is calcium hydroxide, is it soluble

slightly soluble in water

limewater

acids are proton ______

what makes the solution acidic

donors

H⁺ ions make the aqueous solution acidic

bases are proton _______

what makes the solution alkaline

acceptors

OH^- ions make the aqueous solution alkaline

what are bases vs alkali

alkali are soluble in water

bases may not be soluble

all alkali are bases but not all bases are alkali

general equation

metal + acid →

metal + acid ⟶ salt + hydrogen

Zn + H2s04 →

general equation

acid + base →

acid + base ⟶ salt + water

Metal oxides and metal hydroxides act as _____

Metal oxides and metal hydroxides act as bases

If in an acid-base reaction there is effervescence produced then the base must be a metal _______ which produces ____ ______ gas.

If in an acid-base reaction there is effervescence produced then the base must be a metal carbonate which produces carbon dioxide gas.

general equation

metal oxide + acid

metal oxide + acid → salt + water

(metal oxide is a base)

general equation

metal hydroxide + acid

metal hydroxide + acid → salt + water

(metal hydroxide is a base)

acid + ammonia →

acid + ammonia → ammonium salt

metal carbonate + acid →

metal carbonate + acid → salt + carbon dioxide + water

In basic (alkaline) conditions litmus paper turns ____ to _____

red to blue

metal oxides, hydroxides and carbonates are bases, but also this weird one:

ammonia solution

when ammonia gas dissolves in water it forms ammonium hydroxide. Be careful to use the correct terminology: ammonia is the gas, NH₃, ammonium is the ion present in ammonium compounds, NH₄⁺

simple def, how to make an soluble salt

with solution + solid

from reaction of an acid with an insoluble base (in excess)

how is excess insoluble base removed

filtration

why add insoluble base in excess

the insoluble reactant is added in excess to ensure that all of the acid has reacted

• any unreacted acid would become dangerously concentrated during evaporation and crystallisation

what is left after reaction, once acid reacted and solid base removed

Since all of the acid has reacted and the excess solid base has been removed then the solution left can only be salt and water

copper oxide + sulfuric acid equation, symbols

CuO (s) + H₂SO₄ (aq) ⟶ CuSO₄ (aq) + H₂O (l)

how to sample of a dry soluble salt starting from an acid and an alkali - (8)

two parts

1. add alkali + phenolphthalein indicator to conical flask (25cm3 using pipette)

2. add acid to burette, record starting volume

3. add acid to alkali , swirling flask, until indicator changes colour. calculate volume of acid used.

4. repeat 1-3 and add acid dropwise near the point of neutralisation (colour change).

5. repeat 1-3 without indicator

6. transfer solution to evaporating dish/basin. heat until half water is evaporated, leave in warm place to cool and crystallise.

7. filter + rinse crystals with distilled water

8. leave to dry

why leave water behind in evaporating dish when crystalising

to allow for water of crystallisation in some salts and also to prevent the salt from overheating and decomposing.

reaction name for making insoluble salts

what is it

precipitation reaction

two solutions mixed together create insoluble salt

what is the pattern of a precipitation reaction

soluble salt 1 + soluble salt 2 ⟶  insoluble salt + soluble salt 3

AB + CD ⟶ AD + CB

how is precipitate recovered form result solution

precipitate is recovered by filtration and then it must be washed with distilled water remove contaminants, then left to dry

logic for a pure, dry sample of hydrated copper(II) sulfate crystals

CuSO4 is soluble, so either (acid/alkali titration - soluble salt) or (acid/excess insoluble base - soluble salt)

to make CuSO4 - H2SO4 + CuO

CuO, or any other copper metal compound will be INSOLUBLE

so need excess insoluble base (CuO) + acid (H2SO4)

steps for cuso4

1. heat acid until warm, then add CuO (insoluble) base until no more dissolves, mix with glass stirring rod.

2. filter mixture to remove excess base, transfer to evaporating dish

3. evaporate half the water from solution, leave to dry in warm place

4. filter/rinse the crystals with distilled water, leave to dry

why use excess CuO

so that all acid has reacted, otherwise it would become too concentrated and dangerous

also so that the acid doesn’t contaminate the crystals

why use a glass stirring rod instead of metal spatula

because metal could react with acid, glass won’t

why do crystals appear as the solution cools

if solution is saturated when hot

as it cools, it can dissolve/hold less crystals

so crystals form

how to prepare a dry sample of lead(II) sulfate from two soluble salts (solid first)

name of reaction

precipitation reaction

1. dissolve salts in water

2. mix together, stir with glass rod

3. filter to remove precipitate

4. rinse precipitate with distilled water

5. leave to dry

what are two salts that can be used to make lead sulfate

word equation

symbol equation

lead(II) nitrate + potassium sulfate → lead(II) sulfate + potassium nitrate

Pb(NO₃)₂  (aq) + K₂SO₄ (aq) → PbSO₄ (s) + 2KNO₃ (aq)