Acids Flashcards
Acids
Substances with a pH of less than 7
Alkalis
Substances with a pH of more than 7
Neutral substances
Substances with a pH of exactly 7
Bases
Substances that react with acids to form salt and water
Difference between alkali and base
Alkali is a base that is soluble in water, whereas a base itself is not soluble in water
Indicator
A dye that changes colour depending on the pH level
Litmus colour changes
Red if acidic, purple if neutral and blue if alkaline
Methyl orange colour changes
Red if acidic, yellow if neutral or alkaline
Phenolphthalein colour changes
Colourless if acidic or neutral and pink if alkaline
Neutralisation
Name of reaction between acid and base to form salt and water
What do strong acids do and what is their pH?
Ionise almost completely in water and have a pH of 0-2
What do weak acids do and what is their pH?
Do not fully ionise in solution and have a pH of 2-6
What does strength of an acid measure?
What proportion of acid molecules dissolve in water
What does concentration of an acid measure?
How much acid there is in a litre of water
What is a concentrated acid?
An acid with a large number of acid molecules compared to the volume of water
