SC8 Flashcards
What is the pH scale?
Its a measure of how acidic or alkaline a solution is.
How does the pH scale work?
Goes from 0-14.
Neutral is 7
Acidic is below 7
Alkaline is above 7
What is a base?
A substance that reacts with an acid to reduce salt and water.
What is an alkali?
It’s a base that is soluble in water.
What do alkalis form in water?
OH- ions.
What do acids form in water?
H+ ions
What is an indicator?
Its a dye that changes colour depending on whether its above or below a certain pH.
How do you use indicators?
Add a few drops to the solution you’re treating, then compare the colour the solution goes tot he pH chart for that indicator.
What are some indicators?
Universal
Litmus
Methyl orange
Phenolphthalein
What colours show acids on different indicators?
Universal - red
Litmus - red
Methyl orange - red
Phenolphthalein - colourless
What colours show alkalis on different indicators?
Universal - blue
Litmus - blue
Methyl orange - yellow
Phenolphthalein - pink
What colours show neutral on different indicators?
Universal - green
Litmus - blue
Methyl orange - yellow
Phenolphthalein - colourless
What is the reaction between an acid and a base called?
Neutralisation
What does a reaction between an acid and a base form?
Salt and water.
What happens to the ions at neutralisation?
The concentration of H+ ions is equal tot he concentration of OH- ions.
The pH is 7.