3.4.1 pH and Indicators Flashcards
What is the pH scale?
The pH scale is used to describe how acidic or alkaline a solution is.
What do the pH values mean?
pH < 7 is acidic
pH = 7 is neutral
pH > 7 is alkaline
Acids and alkalis can be stronger or weaker. It depends how far away from pH 7 it is.
What does an indicator do?
An indicator is a substance that changes colour to tell you about the pH of a solution.
What colour does methyl orange go in acid?
Red
What colour does methyl orange go in a neutral solution?
Yellow
What colour does methyl orange go in an alkali?
Yellow
What colour does phenolphthalein go in acid?
Colourless
What colour does phenolphthalein go in a neutral solution?
Colourless
What colour does phenolphthalein go in an alkali?
Pink
What colour does red litmus go in acid?
Red
What colour does red litmus go in a neutral solution?
Red
What colour does red litmus go in an alkali?
Blue
What colour does blue litmus go in acid?
Red
What colour does blue litmus go in a neutral solution?
Blue
What colour does blue litmus go in an alkali?
Blue