Acids, bases and salt preparations

What is the mnemonic for the ions that are always soluble?

SNAP

S- Sodium

N- nitrates

A- ammonium

P- potassium

What is the mnemonic to memorise the solubility of chlorides?

All chlorides are soluble except lead, mercury or silver

LMS

What is the mnemonic to memorise the solubility of sulfates?

All sulfates are soluble except calcium, barium and silver + lead

CBS + lead

What is the mnemonic to memorise the solubility of carbonates and hydroxides?

All carbonates and hydroxides are soluble unless paired with the SNAP ions

What is the solubility of nitrates?

All nitrates are soluble

What are acids in terms of protons?

Proton donors- produce H⁺ ions

What are alkalis in terms of protons?

Proton acceptors- OH- ions can accept protons

What is the equation for an acid reacting with a metal?

Metal + acid —> salt + hydrogen

Equation for reaction with acid and base

Base + acid —> water + salt

Equation for reaction of acid with metal carbonate

carbonate + acid —> water + carbon dioxide + salt

What are the two methods of making a soluble salt?

Adding acid to a metal/oxide/carbonate

Reacting a dilute acid and a soluble base ( titration)

How do you react a metal/oxide/carbonate with an acid (excess solid method)?

Heat acid until warm

Add solid

Stir until stops disappearing

Filter mixture to remove excess

Transfer solution to an evaporating basin

Evaporate water using heat and allow crystals to form

How do you react a dilute acid and a soluble base ( titration method) ?

Add alkali and indicator to a conical flask using a pipette

Add acid to burette noting starting volume

Add acid to alkali slowly until indicator changes colour

Evaporate water using heat

leave solution to cool so crystals form

filter to obtain crystals

dry crystals in oven

Why is solid oxide often added in excess in the excess solid method?

To avoid leaving any unreactive acid which may become dangerously concentrated during evaporation and crystallisation

How can an insoluble salt be made?

Using the precipitation method

What is the method for precipitation when making an insoluble salt?

Mix two soluble salts to form precipitate using stirring rod

Filter the precipitate from the filtrate

Wash the precipitate to remove any traces of the other solution

Dry the precipitate in an oven

What is meant by the term precipitate

A solid formed when two solutions are mixed

What is the equation for making an insoluble salt using the precipitation method?

Soluble salt 1 + soluble salt 2 —> insoluble salt + soluble salt 3

what colour is litmus in acids, neutrals and alkalis?

red, purple, blue

what colour is methyl orange in acid, neutral and alkali?

red, orange, yellow

what colour is phenolphthalein in acid, neutral and alkali?

colourless, colourless, pink

why is a pipette not suitable for adding the acid in a titration?

it measures only one volume

how will you know when the reaction between soluble salts to make an insoluble salt is complete?

no more precipitate forms