Learning Outcomes

Having taken part in practical activities to
compare the properties of acids and alkalis,
I have demonstrated ways of measuring and
adjusting pH and can describe the
significance of pH in everyday life
Concept Card
If oranges contain citric
acid, why don’t they
poison you?
There is a difference
between acids in food
and acids in the
environment.
They are poisonous,
but the acid is not
concentrated enough
to be harmful.
Not all acids are
poisonous.
Acids and Alkalis
Acid, Alkali or Neutral Solutions

Solutions can be classed as either acid, alkaline, or
neutral. We use a scale called the pH scale in order
to do this. The scale goes from pH 1 to 14. A liquid
which changes colour called universal indicator can
be added to solutions to match up to a number on the
pH scale. This scale is shown here:-
Acid, Alkali or Neutral Solutions
Q1.
Q2.
Q3.
Q4.
Q5.
What is the name of the scale used to classify solutions
as acid, alkaline or neutral?
Name the liquid added to solutions which changes
colour to indicate if they are acid, alkali or neutral?
Which numbers on the scale indicate a solution is an acid?
Which numbers on the scale indicate a solution is an alkali?
Which number on the scale indicates a solution is
neutral?
Collect a pH scale
and stick it into
your jotter.
Experiment




You are going to test some household substances to find out if
they are acid, alkaline, or neutral.
Collect a dimple tray and place a few drops of each substance on
separate dimples.
Add a drop of universal indicator to the substance and compare
the colour with the pH chart.
Copy the table on the next slide and complete it as you collect
your results.
Common Solutions and their pH Numbers
Name of
Solution
Q1.
Q2.
Q3.
Colour with
universal
indicator
pH
number
Which of the solutions were acid?
Which of the solutions were alkali?
Which of the solutions were neutral?
Acid,
Alkali or
Neutral
Make your own indicator…
Collect the experiment card
Summary





Acid solutions have a pH range of 1 to 6
Alkaline solutions have a pH range of 8 to 14
Neutral solutions have a pH of 7
Universal indicator can be used to test the pH of a
substance
We use a scale called the pH scale.
You can now collect
homework four