Acids, Bases and Salts Flashcards
What is an acid
Reacts with bases to make a neutral solution
Dissociates in water to form hydrogen ions (H+)
Proton donor
What is a base
A substance that will react with an acid to form a neutral substance
NOT ALWAYS ALKALINE
What is an alkali
Soluble base
When dissolved in water, increases concentration of hydroxide ions (OH-)
Proton acceptor
Examples of bases
Metal oxides
Metal hydroxides
Ammonia
pH neutral
7
UI green
Why is universal indicator useful
Can be used to determine all pH, not just acidic/alkali/neutral
Colour of litmus
Acidic: red
Alkali: blue
Neutral: no change
Colour of phenolphthalein
Acidic: colourless/no change
Alkali: bright pink
Neutral: colourless/no change
Colour of methyl orange solution
Acidic: red
Alkali: yellow
Neutral: orange/no change
Neutralisation
Reaction between acid and alkali Hydrogen ions (protons) neutralised by hydroxide ions to produce water molecule Acid donates proton, alkali accepts
Which 3 ions are always soluble?
Na, K, NH4
Nitrates solubility
Soluble
Chlorides solubility
Soluble except PbCl2 and AgCl
Sulphates solubility
Soluble except PbSO4, BaSO4 and CaSO4
Carbonates solubility
Insoluble except Na2CO3, K2CO3 and (NH4)2CO3
Hydroxides solubility
Insoluble except NaOH, KOH and NH4OH
CaOH is slightly soluble
What is produced when a metal and an acid react?
Metal + acid -> salt + hydrogen
What is produced when a metal hydroxide and an acid react?
Metal hydroxide + acid -> salt + water
What is produced when a metal oxide and an acid react?
Metal oxide + acid -> salt + water
What is produced when a metal carbonate and an acid react?
Metal carbonate + acid -> salt + water + carbon dioxide
Strong vs weak acid
Strong acid forms more H+ ions when it dissolves in water, every molecule dissociates into ions
Weak acid doesn’t form as many H+ ions, only some molecules dissociate
Concentrated vs dilute acid
Concentrated acid has more molecules in a given volume of water
Which acids are strong or weak?
Strong - hydrochloric, sulphuric and nitric
Weak - carbonic, ethanoic
How to make soluble salts (except Na, K, NH4)
Use insoluble base + acid method
Warm acid in beaker and add solid until no more dissolves
Filter to remove excess solid
Heat filtrate solution until crystals form
Filter to obtain crystals and dry in a warm oven
How to make Na, K, NH4 salts
Use titration method
How to make insoluble salts
Use precipitation reaction method
Mix 2 solutions (with soluble salts) together
Filter to remove solid
Dry solid in warm oven
