2. NEUTRAL

3. Chemical reaction to make...
Use a neutralisation
Chemical reaction to make... ?
UNKNOWN
DISCOVER

4. Mixing a strong acid and a strong base
What happens when a strong acid and a strong base are mixed? ?
Mixing an acid and a base causes a chemical change.
This chemical change is called a chemical reaction.
How do you know this chemical reaction has taken place?

5. 1. Measure 5 cm3 hydrochloric acid (1
1. Measure 5 cm3 hydrochloric acid (1.0MHCl) pour into evaporating dish – test pH using 2 drops of universal indicator solution, note down observation and pH
2. Rinse the measuring cylinder with distilled water. Measure 5 cm3 sodium hydroxide (1.0MNaOH) – test pH using 2 drops of universal indicator solution, note down observation and pH.
3. Add NaOH to evaporating dish with the acid.
4. Gently mix the solutions with the stirring rod for 1 minute
What is the pH and color after mixing?
5. Place the evaporating dish on the gauze. Light the Bunsen burner. Make sure the Bunsen burner is directly below the evaporating dish.
6. Heat very gently until all the liquid has evaporated. The hot liquid may ‘spit’. How can you do this safely?
7. When all the liquid has evaporated, turn off the Bunsen burner. Be careful not to touch any of the equipment, WHY? What is left?
8. Add 2 drops of universal indicator liquid to the substance. What color did it turn? and what is the pH?

6. Colour of universal indicator
Results/Observation
Chemicals to test
Colour of universal indicator pH
Hydrochloric acid
Sodium hydroxide
Solution obtain from mixing acid and base
Substance from step 8

7. Neutralisation is a very clean process…
We take an acid and base…
And just get a salt and water.
Let the water evaporate and we’ll just be left with the crystallised salt…
…as long as we start with just the right amount of acid and base so neither is left over.

8. Definition
A neutralisation reaction between a strong acid and a strong base is where the acid reacts with the base to produce a neutral solution of a salt and water.
sodium hydroxide
pH 14
neutralisation
sodium chloride
pH 7
hydrochloric acid
pH 1

9. All these will neutralise an acid
Type of compound
Contain
React with acids to give
Metal Hydroxides
Metal Oxides
Metal Carbonates
OH-
water + a salt
O2-
water + a salt
CO32-
water + a salt + CO2

10. Uses of sodium chloride salt
Sodium chloride is used:
As table salt.
To preserve meat and vegetables.

11. SUMMARY Acids Bases Red Neutralization Purple 1 14 Water Salt Green
React with
Bases
Change universal indicator to
Change universal indicator to By
Red
Neutralization
Purple
Which represent a pH value of
To produce
Which represent a pH value of 1 14
Water
Salt
Which is use for
Change universal indicator to
Change universal indicator to
Green
Preservation
Green
Which represent a pH value of
Which represent a pH value of 7 7

12. Evaluation
Question 1: a. Name the acid reactant in your experiment. 1mrk
b. Name the base reactant in your experiment. 1mrk
Question 2: a. Explain what neutralisation means. 3mrks
b. State the neutral products you have ended up with? 2mrks
Question 3: a. Besides bases, state another chemical that can neutralize an acid? 1mrk
b. State the products from this reaction? 3mrks

13. Evaluation
Question 4: a. What did you observe about the colour after mixing the acid with the base? What does this tell you about the solution? 2mrks
b. When 2 drops of universal indicator was added to the substance in step 8, what did you observe about the colour of the indicator? What does this tell you about the substance made? 2mrks
c. State two uses of sodium chloride salt. 2mrks

14. Answers Neutralisation
Question 1: a. Name the acid reactant in your experiment.
Hydrochloric acid
b. Name the base reactant in your experiment.
Sodium hydroxide
Question 2: a. Explain what neutralisation means.
Neutralisation is the chemical reaction that takes place when an acid reacts with a base. New chemicals are made which are neutral.
b. State the neutral products you have ended up with?
sodium chloride
water
Question 3 a. Besides bases, state another chemical that can neutralize an acid?
b. State the products from this reaction?
Metal Carbonate
Salt, water and carbon dioxide gas.

15. Answers Neutralisation
Question 4 a. What did you observe about the colour after mixing the acid with the base? What does this tell you about the solution?
b. When 2 drops of universal indicator was added to the substance what did you observe about the colour of the indicator? What does this tell you about the substance made?
The solution/substance went green, meaning that there was no base or acid left over, just the neutral products.
c. State two uses of sodium chloride salt.
Sodium chloride is used as table salt and to preserve meat and vegetables.