Acids and BasesAnd Neutralisation Reactions p. 80-82

What are acids?Working together with your bench group & using the information in your text book (Ch 4 p 80),

expand this Mind Map

Acids

Have a sour taste

eg

Are used for

What are bases?

Working together with your bench group, expand this Mind Map

bases

Have a bitter taste

(think of baking soda!)

eg

Are used for

Experiment 13: Testing for Acids and Bases

Aims: to determine which substances are acids and bases using universal indicator to compare the colour produced using plant indicators with those produced

using universal indicator

Materials

Glass plate with wells Droppers Universal indicator Colour chart Red Cabbage Indicator Hydrochloric acid (HCl) Sodium Hydroxide (NaOH) Vinegar Lemon Juice Sodium bicarbonate (NaHCO3) Water (from tap) Other Substances as supplied

Method

1. Collect the substances listed above and place about 0.5 ml in separate wells on the glass plate, as shown.

2. Use a new well for each substance. 3. Add two drops of Universal indicator to each well 4. Record the colour that the indicator became 5. Use the glass test plate outline supplied to estimate the pH and

record this also. 6. Test these substances with Red Cabbage Indicator and record the

colours on a new sheet Hydrochloric acid (HCl) Sodium Hydroxide (NaOH) Vinegar Lemon Juice Sodium bicarbonate (NaHCO3) Water (from tap)

Copy the table on the next slide into your workbook Safety Issues?

Comparing Indicators

Substance tested Colour with Universal Indicator

pH as read from Chart

Colour with Red Cabbage Indicator

Hydrochloric acid

Sodium hydroxide

Vinegar

Lemon juice

Sodium bicarbonate

solution

Tap water

Neutralisation Reactions

Acids and bases react together! (Remember the vinegar and Bicarb?) The general overall word equation is

Acid + Base a Salt + water

Except if you use a bicarbonate or carbonate (which are bases) and then it’s

Acid + bicarbonate/carbonate a Salt + water + carbon dioxide

Try This!

1. Put a small amount of vinegar + 2 drops only of indicator in a test tube

2. Add 0.1 M NaOH drop by drop

3. Can you get the pH to be just 7?

Activities

On the Intranet in the Acids and Bases Section try GEMS Alien Juice Bar

Treasure Puzzle