Do now!

Can you stick the target sheet for the new topic in your

book please?

Then fill in the first column.

Reminder!

• Sound and Light tests on Thursday

• Speeding Up and Energy tests Monday

www.MrSimonPorter.wikispaces.com

Acids and alkalis

What have you remembered?

Acid tastes

Acid tastes

Acid comes from the latin word acer, which means sharp. Acids are sharp tasting! (“Tangy”)

Indicators

Indicators are chemicals (coloured dyes) which change colour in acids and alkalis.

Litmus

Turns red in acid

Turns blue in alkali

Litmus

Turns red in acid

Turns blue in alkali

Litmus can tell us if something is an acid or an alkali, but it cannot tell us how strong the

acid or alkali is

Other indicators

Red cabbage and beetroot make excellent indicators

The pH scale

The strength of an acid is measured on the pH scale

pH stands for the “potential of hydrogen”

Universal Indicator

To measure pH, we need an indicator that has a different colour for each value of pH

Universal Indicator

Universal Indicator

It comes in the form of a paper

Universal Indicator

It also comes in the form of a liquid

Neutralisation

Neutralisation

What happens when we add an acid to an alkali?

Neutralisation

Acid + alkali salt + water

Both neutral

Examples of neutralisation

Metals and acids

Hydrochloric acid + magnesium magnesium chloride + hydrogen

Nitric acid + iron iron nitrate + hydrogen

Sulphuric acid + zinc zinc sulphate + hydrogen

In general, hydrochloric acid makes a chloride, nitric acid makes a nitrate, and sulphuric acid makes a sulphate.

“salts”

Acid + carbonate

Acid + carbonate “salt” + carbon dioxide + water

Hydrochloric acid + sodium carbonate sodium chloride + carbon dioxide + water

Sulphuric acid + calcium carbonate calcium sulphate + carbon dioxide + water

Nitric acid + copper carbonate copper nitrate + carbon dioxide + watera “salt”

Today’s lesson

• Testing the pH of soils around the school

Stick it in! (9Ga/3)

Testing soil for pH

• Make notes of location, plants and description of the soil

• Put a couple of spatulas of soil carefully in a test tube

• Half fill the test tube with DISTILLED WATER, put a bung in and gently shake

• Allow the soil to settle

• Test pH using Universal Indicator paper

You have 35 minutes

Oh no!

Let’s read pages 86 and 87

• Questions on pages 86 and 87