Wigmore High School Summer Learning 2020

Subject: Science (chemistry) Year group: 7 Group/Set/Class: All Teacher:

SJones/ACawthorn/JMelvin/ELong

Date work set: 27/04/20 Date work to be completed by: 01/05/20

Topic: Acids and alkalis

Learning outcomes:

• Compare the properties of acids and alkalis

• Describe how indicators, including the pH scale, categorise solutions as acidic,

alkaline or neutral.

• Describe how pH changes in neutralisation reactions.

Instructions:

Complete all of the work in each lesson using the sheets provided. Your class teacher will

email you with a word version of the work. This work should take approximately 3 hours.

There are extension activities to complete as well if you complete all work.

Please email your completed work back to your class teacher by 3.30pm Friday afternoon.

Acids and alkalis lesson 1

For this lesson you will need to use the student textbook section 4.1 acids and

alkalis.

It looks like this

1. You can also use this link https://www.youtube.com/watch?v=NoZmrwf1I_w

to help you answer the following questions:

• Name 5 examples of acids

• What type of taste do acids have?

• Name 5 examples of Alkalis

• What type of substances are alkalis?

2. Some acids and alkalis are safe to eat or use, but some are very dangerous.

Many have hazard symbols on them to help you understand the precautions

you need to take to when using them.

a) Name two ways you could protect yourself when using these substances

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

b) Complete the table below, you need to research this.

https://www.bbc.co.uk/bitesize/guides/zsfpb82/revision/1

Link the hazard symbols with their name and description.

Old

hazard

symbol

New

hazard

symbol

Name Description

1

Corrosive

This may dissolve or

burn materials,

including skin

2

Health

hazard

(Harmful)

This includes irritants,

harmful substances,

and some low-hazard

substances

3

Explosive

This contains dangerous

organisms such as

bacteria

4

Flammable This can be poisonous

and possibly deadly

5

Toxic This may explode

6

Caution

(Irritant)

This can catch fire

easily

3. The hazards associated with acids and alkalis depends on how concentrated

or dilute they are – this mean how much water there is mixed with the

substance.

Complete the diagrams (using circles) and sentences below to describe

the difference between concentrated and dilute.

Concentrated solutions have many/few particles of

the acid or alkali. They have many/few water

particles.

Concentrated

Dilute solutions have many/few particles of the acid

or alkali. They have many/few water particles.

Dilute

Acids and alkalis lesson 2

For this lesson you will need to use the student textbook section 4.2 Indicators and

pH.

It looks like this

1. Before doing anything! See if you can answer these questions without using

the book, we will come back to them at the end of the lesson too. Put a T/F

next to the question – it doesn’t matter if they are wrong.

True or False?

1. Acids turn universal indicator blue

2. Litmus paper is always red

3. Acids can only be strong

4. Neutral substances turn Universal indicator green

5. Alkalis turn universal indicator blue

6. Alkalis can be weak or strong

2. Answer the following questions:

• What is an indicator?

• What plants can be used as indicators?

• What colour does red litmus turn in alkali?

• What colour does blue litmus turn in acid?

3. Colour in the pH scale/ add coloured boxes if on computer.

Label acid, alkali and neutral on the scale.

Label everyday substances in the place they would be on the pH scale.

4. Why is the pH scale different from other indicators? What does it tell you?

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

5. Colour in the strip of indicator paper in each box to show its colour with universal indicator. You can print this out or put coloured boxes over each I have shown an example below.

Toothpaste

pH 9

Washing powder

pH 10

Vinegar

pH 3

Pure water

pH 7

Fizzy drinks

pH 4.5

Oven cleaner

pH 13

Soap

pH 8

Salt water

pH 7

Stomach acid

pH 2

Hair dye

pH 11

Sea water

pH 8

Rainwater

pH 5.5

Sugar solution

pH 7

Lemon juice

pH 2.5

Milk

pH 6.5

Baking soda

pH 9

6. How much do you know now? Complete the questions again from the

beginning of the lesson.

True or False?

1. Acids turn universal indicator blue

2. Litmus paper is always red

3. Acids can only be strong

4. Neutral substances turn Universal indicator green

5. Alkalis turn universal indicator blue

6. Alkalis can be weak or strong

Extension

Make your own indicator

https://www.3plearning.com/blog/simple-chemistry-experiments-kids-home/#Cabbage

Follow the method for making red cabbage indicator on the link provided.

Take pictures of your experiment – can you make an indicator scale? What colours are acids? What

colours are alkalis?

Draw a results table to show your results.

Please only do this if you have the equipment to, don’t go and buy things if

you do not need to.

Extension if you cannot do the experiment

What doe pH mean?

What type of ions do all acids contain?

What type of ions do all alkalis contain?

Acids and alkalis lesson 3

For this lesson you will need to access the student book section 4.3 Neutralisation.

It looks like this

You may also want to use these links to help you:

https://www.youtube.com/watch?v=_cB2vSaalXg

https://www.youtube.com/watch?v=xZtqzBgSqnI

https://www.bbc.co.uk/bitesize/guides/z89jq6f/revision/1

How are indigestion tablets and farmers soil linked? A process called neutralisation.

When you add an acid to an alkali, they cancel each other out to make a neutral

solution (neither acid nor alkali).

pH1

pH11 pH7

1. A) Find out the names of 3 acids that may be used in the laboratory:

b) Find out the names of 3 alkalis that may be use in the laboratory:

2. Complete the sentences use the word box to help you. You can use the

words once, more than once or not at all.

Neutralisation is when an __________ and _________ are mixed together to

form a ___________ solution (pH7).

If an alkali is added to an _______ of pH 1, the pH will _________ until it

reaches___________. If more alkali is added, the neutral solution will become

more ___________.

Neutral acid alkali

Increase decrease stay the same

pH7 pH1 pH11

alkaline acidic

3. Complete the questions below:

1 Look at the picture. What type of substance will neutralise an acid?

Another mechanic suggests using one of the other substances in the picture to neutralise the acid.

2 a Which of the materials shown in the diagram would not neutralise the spilt

acid?

b Explain why this material cannot be used.

3 The car mechanics decide to use the sodium hydroxide drain cleaner. The word equation for the reaction is

sulfuric acid + sodium hydroxide → sodium sulfate + water

Each sentence below contains a mistake. Cross out the incorrect word and write in the correct one.

a Neutralisation is a physical change because new substances are formed.

b They could use an adjudicator to show when the acid has been neutralised.

c When the neutralisation is complete there is only sodium hydroxide left in the water.

d Sodium sulfate is one of the reactants in the reaction.

Extension

When looking at neutralisation reactions we have to be able to write word equations. We put the

reactants (things that react together) on the left and the products (things we make) on the right. We

join them together with an arrow in the middle.

sulfuric acid + sodium hydroxide → sodium sulfate + water

Reactants Products

Water Hydrochloric

acid Sodium

hydroxide Water

Potassium citrate

Lithium chloride

Potassium hydroxide

Nitric acid Sodium

ethanoate Ammonium hydroxide

Calcium hydroxide

Ammonium nitrate

Water Sulfuric acid Calcium sulfate

Ethanoic acid

Water Water Lithium

hydroxide Citric acid

Use this table to write out the word equations for 5 neutralisation reactions. You can

print them and cut them out if you need to.