1. Acids and Bases
Year 10

2. Chemistry
 Study of Chemicals and how they
react
 Everything is made of chemicals
 They are made of elements.
 There are over 100 elements

3. What are Acids?
 Acids are
common
 Some are
dangerous and
can burn your
skin
 Some are safe to
eat and drink
 Stomach acid
helps digest food explosion

4. Acids
 Definition
• A group of compounds which behave similarly
• All have low pH
• Turn Litmus paper RED
• All donate H+ ions in aqueous solution
 Examples
• Hydrochloric HCl
• Sulfuric H2SO4
• Nitric HNO3
• Ethanoic CH3COOH

5. Acids
 A dilute acid has lots of water and a
small amount of acid
 A concentrated acid has lots of acid
and not much water so must be
handled carefully
 A strong acid releases lots of H+
 A weak acid releases fewer H+

6. What are Bases (Alkalis)?
 In our home we
often use bases
to clean things.
Eg Bleach and
toothpaste
 Some things are
not acids or
bases, we say
that they are
neutral. Eg
Water

7. Bases
 Definition
• A family of compounds that behave
similarly
• Have a high pH
• Turn litmus BLUE
• All donate OH-
 Examples
• Ammonia NH3
• Sodium Hydroxide NaOH

8. Measuring acid strength?
 To decide if something is an acid or a
base we can use an indicator.
 Litmus and Universal Indicator are
examples of indicators.
 They change colour depending on if
they are in an acid or a base.

10. Working with Indicators
 Red litmus turns BLUE in the
presence of Bases
 Blue litmus turns RED in the
presence of acid
 Acids and bases react together in
a NEUTRALISATION reaction

11. Acid Reactions
 Acid + Base  Salt + Water
 Acid + Metal  Salt + Hydrogen
 Acid + Carbonate  Salt + Water + Carbon Dioxide
• Hydrochloric acids (HCl) form CHLORIDE salts
• Nitric acid (HNO3) forms NITRATE salts
• Sulfuric acid (H2SO4) forms SULFATE salts

12. Acid Rain
 Consider
• Causes
 natural
 human
• Effects
 buildings
 flora
 fauna
 health
• Chemical equations
• Prevention/Solution

13. Testing Gases
 Hydrogen -

14. Testing Gases
 Hydrogen - POP TEST
• Explodes with a squeaky pop
 Carbon Dioxide –

15. Testing Gases
 Hydrogen - POP TEST
• Explodes with a squeaky pop
 Carbon Dioxide – Limewater goes
cloudy
 Oxygen –

16. Testing Gases
 Hydrogen - POP TEST
• Explodes with a squeaky pop
 Carbon Dioxide – Limewater goes
cloudy
 Oxygen – Relights a glowing splint

17. Antacid Investigation
 NZ facts 2007
• 70% population get
heartburn /GERD
• $9m on 1 brand!
• 3rd most widely
prescribed medicine
 Which brand is the
best?

18. Identify Unknown Solutions

19. Rates of Reaction
 Factors increasing the rate of
reaction
• Surface area
• Concentration
• Temperature
• Catalyst/Enzyme
• Pressure

20. Metals/periodic table
 , Element, compound, exo/endo

21. Method
1. Collect the 4 substances to be
tested
2. Place a drop of the first substance
in the spotting tile
3. Test the substance with a drop of
universal indicator
4. Record the result
5. Repeat steps 1-4 with the
remaining 3 substances

22. Results
Substance Universal indicator
colour
Hydrochloric acid
Ammonia
Water
Sodium Hydroxide

23. Experiment write up
 Title Working with Indicators
 Aim To find out what happens when….
 Method As previous slide, short bullet point
 Diagram Half page, labels, straight lines
 Results Draw your table
 Conclusion Write about what you learnt from the
experiment. “Universal indicator turns blue in
bases, red in acids and green when solutions are
neutral. …was a base because it turned blue
when we added indicator. …. Was an acid as it
turned red when we added indicator. …. Was
neutral as it turned green when we added
indicator”

24. Investigate an Acid
 Vinegar is an acid
 Add some powders to vinegar and
OBSERVE what happens
• Dissolve – powder is soluble
• Doesn’t dissolve – powder is insoluble
• Fizzing – reaction is occurring gas given off
• Heat – does it get hot or not
• Smell – gas given off
• Colour change

25. Experiment time!

26. Method
1. Collect 5 test tubes in a test tube rack
2. Put 1 spatula of either sugar, salt, baking
soda, flour, washing powder into each
test tube
3. Collect vinegar in a 50ml beaker
4. Add 5ml vinegar to a test tube and
observe what happens
5. Record results in a table
6. Repeat step 4 and 5 until all test tubes
are tested

27. Results
Substance Observations
(Dissolves, fizzes, smells etc.)
Sugar
Salt
Etc.

28. Experiment write up
 Title Reactions with Acid
 Aim To find out what happens when….
 Method As previous slide, short bullet
point
 Diagram Half page, labels, straight lines
 Results Draw your table
 Conclusion Write about what you learnt
from the experiment. “Some substances
are able to dissolve completely and form a
solution. Others will not dissolve and are
insoluble.”

29. Acid Extension
 Test series of fruit juices with
indicator
 Which has most acid
 Rot teeth
 Write up

30. Investigating Evaporation
 When water is heated
it turns from a liquid
into a gas (steam)
 This is called
evaporation
 Some things dissolved
in the water will be
left behind when the
water is heated
 Evaporation can be
used to separate some
solutions

31. Method
1. Place 2g of salt and 10ml of warm water
into a test tube
2. Place thumb over the top and shake to
dissolve.
3. Pour 5ml of the salt solution into an
evaporating dish
4. Light the Bunsen and turn to a blue
flame
5. Heat the mixture until almost all the
water has disappeared.
6. Observe and record what happens

32. Experiment write up
 Title Investigating Evaporation
 Aim To find out what happens
when….
 Method Short bullet points
 Diagram Half page, labels, straight
lines
 Results Describe what happend
 Conclusion Write about what you
learnt from the experiment.

33. Testing for Glucose
 Glucose is a sugar
 Benedict’s solution is used to test for
glucose
 Add Benedict’s to the sample and
heat, it turns ORANGE if glucose is
present

34. Forensic Scientists
 Police often need
scientists to help
determine the cause
of death
 This person died
holding 4 bags of
white powder (salt,
glucose, starch,
baking soda)
 You must investigate
the substances and
identify what they are

35. Design your Experiment
 You have:
• Vinegar
• Water
• Benedict’s solution

36. Unknown Solutions
 You have been given four solutions
(glucose, salt, baking soda and vinegar)
 The labels have fallen off!
 Design an experiment which will allow you
to identify the solutions
• Evaporation
• Benedict’s
• Universal indicator
• Water