Acids and Metal Hydroxides ©cgrahamphysics.com 2016

Plants are natural pH indicators • Which plants do you think indicate an acidic soil? Which an

alkaline soil? Can you put them in order of their pH value?

hydrangea

©cgrahamphysics.com 2016

Starter Write out the word equation and symbol for

• Zinc oxide reacting with hydrochloric acid Zinc oxide + hydrochloric acid zinc sulfate + water

ZnO + 2HCl ZnCl2 + H2O

• Magnesium oxide reacting with sulfuric acid Magnesium oxide + sulfuric acid magnesium sulfate + water

MgO + H2SO4 MgSO4 + H2O

• Sodium oxide reacting with nitric acid Sodium oxide + nitric acid sodium nitrate + water

Na2O + 2HNO3 2NaNO3 + H2O

©cgrahamphysics.com 2016

Aim • By the end of this lesson I will be able to use

word equations to describe the reaction between acids and metal hydroxides

Key words

• Word equation for metal hydroxides

• Symbol equations for hydroxides

• Name of some hydroxides

©cgrahamphysics.com 2016

Have you ever wondered

The big picture

How do we use hydroxides in everyday life?

©cgrahamphysics.com 2016

Acid + Metal Hydroxide

• If the right amounts of an acid and an metal hydroxide

are added together the pH of the mixture changes to

neutral (pH 7).

• This reaction is called neutralisation.

acid + metal salt + water hydroxide

©cgrahamphysics.com 2016

Neutralisation reactions

A neutralisation reaction occurs when an acid

reacts with an alkali.

ACID + ALKALI SALT + WATER

Na Cl H

H O H Cl Na O

H

HCl + NaOH ClNa + H2O ©cgrahamphysics.com 2016

Acid and metal hydroxide practical

You will need:

• Boiling tube

• Bung to fit tube

• 2x 100 ml beakers

• 2x plastic pipettes

What to do:

1. Pour approx. 50 ml of hydrochloric acid into one beaker and label it.

2. Pour approx. 50 ml of sodium hydroxide into the other beaker and label it.

3. Put about 1cm depth of NaOH into a boiling tube.

4. Using a pipette now add about 1 cm of HCl to the boiling tube

5. Note what happens Wear goggles

©cgrahamphysics.com 2016

Acid and metal hydroxide practical

You will need:

• Boiling tube

• Bung to fit tube

• 2x 100 ml beakers

• 2x plastic pipettes

• UI solution

What to do:

6. Add universal indicator to your boiling tube

7. Using a pipette now add HCl or NaOH to the boiling tube to make it turn neutral

1 2 3 4 5 6 7 8 9 10 11 12 13 14

©cgrahamphysics.com 2016

Questions

• Write word symbol equation for the reaction that took place.

ℎ𝑦𝑑𝑟𝑜𝑐ℎ𝑙𝑜𝑟𝑖𝑐 𝑎𝑐𝑖𝑑 + 𝑠𝑜𝑑𝑖𝑢𝑚 ℎ𝑦𝑑𝑟𝑜𝑥𝑖𝑑𝑒 → 𝑠𝑜𝑑𝑖𝑢𝑚 𝑐ℎ𝑙𝑜𝑟𝑖𝑑𝑒 + 𝑤𝑎𝑡𝑒𝑟

Write symbol equation for the reaction that took place.

𝐻𝐶𝑙 + 𝑁𝑎𝑂𝐻 → 𝑁𝑎𝐶𝑙 + 𝐻2𝑂

• Write the word AND symbol equation for the reaction taking place between a metal oxide and an acid of your choice.

©cgrahamphysics.com 2016

Plenary

• Write down 2 things you have learnt this lesson on post-it note.

• Write down one interesting use of hydroxides.

• Stick them on a table with everyone else.

• Read at least 2 other post-it notes.

©cgrahamphysics.com 2016

Key words

• Word equation for metal hydroxides – acid + metal hydroxide salt + water

• Symbol equations for hydroxides – all hydroxides end in __OH

• Name of some hydroxides – sodium hydroxide, potassium hydroxide, strontium hydroxide, etc

©cgrahamphysics.com 2016