C1.4.2 Indicators and pH Flashcards
What is an indicator?
Something that tells us if a substance is an acid or alkali.
How do indicators work?
They contain a dye which changes colour in acidic and alkaline conditions.
You add blue litmus paper to an unknown solution and it turns red.
You add red litmus paper to an unknown solution and it stays red.
The substance is…
Acidic
You add red litmus paper to an unknown solution and it turns blue.
You add blue litmus paper to an unknown solution and it stays blue.
The substance is…
Alkaline
You add blue litmus paper to an unknown solution and it stays blue.
You add red litmus paper to an unknown solution and it stays red.
The substance is…
Neutral
If you want to know exactly how acidic or alkaline a substance is then we use…
Universal Indicator
Describe a solution that turns universal indicators the following colours:
Describe a solution that turns universal indicators the following colours:
Describe a solution that turns universal indicators the following colours:
Describe a solution that turns universal indicators the following colours:
Describe a solution that turns universal indicators the following colours:
pH1 =
Strong acid
pH2 =
Strong acid
pH3=
Strong acid
pH4 =
Weak acid
pH5=
Weak acid
pH6=
Weak acid
pH7=
Neutral
pH8=
Weak alkali
pH9=
Weak alkali
pH10=
Weak alkali
pH11=
Strong alkali
pH12=
Strong alkali
pH13 =
Strong alkali
pH14=
Strong alkali
Give an example of useful n eutralisation reactions.
Toothpaste is alkaline to neutralise the acids produced by bacteria that cause acid erosion.
Indigestion tablets neutralised stomach acids to prevent heartburn/indigestion.
