© Boardworks Ltd 2004 1 of 20 © Boardworks Ltd 2004 1 of 34 What is an acid? Acids are a group of chemicals. What do you know about acids? Are all acids

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What is an acid?

Acids are a group of chemicals. What do you know about acids? Are all acids dangerous?


What is an acid?

everyday acids laboratory acids

Acids are a group of chemicals.

Can you think of other examples of acids?

Which of these items contains an acid?


What is a weak acid?

Acids are found in household items such as food, drinkand beauty/skincare products.

It is safe to handle these acids and even taste them, if theyare for eating! These acids are known weak acids.


What is a strong acid?

Some acids, like those found in the laboratory or a car battery, are very dangerous (too dangerous to taste or touch).

These acids are said to be corrosive as they can damage other materials by wearing them away! They are strong acids.

Why must strong acids always be handled very carefully?


What is an base?

everyday bases laboratory bases

bases are another group of chemicals, the opposite of acids.

Which of these items contains an base?

Can you think of other examples of bases?


What is a weak base?

bases are found in soaps and other materials used for cleaning.

It is safe to handle these bases, which can feel soapy.These bases are known as weak bases.


What is a strong base?

Some bases, like those in the laboratory or in cleaning materials such as toilet cleaner, are too dangerous to touch.

These bases are said to be caustic because they can burn skin and damage other materials! They are strong bases.

Why must strong bases always be handled very carefully?


How can you tell which chemicals are safe and which are dangerous?

Special symbols are used on bottles and vehicles that contain dangerous chemicals.

What are hazard symbols?

corrosiveharmfulirritanttoxic

These hazard symbols show why the chemical is dangerous.

Why is it important that these symbols can be recognised by

i h

highly flammable

people from other countries?


How can you test a liquid to find if it is an acid or an base?

An indicator is a special chemical that changes to a different colour in an acid or an base.

What is an indicator?

Litmus paper and litmus solution are examples of indicators.

Litmus is red in acid.

Litmus is blue in base.


Litmus is used to show if a solution is acid or base.

Litmus does not show if the acid or base is weak or strong.

What is universal indicator?

Universal indicator has a range of colours that show how weak or strong the acid or base is.

stronger basestronger acid

What is the colour for a weak acid? What is the colour for a strong base?

weak base

weakacid

strongbaseneutral

strongacid


The strength of an acid or base is measured by the pH scale.

What is the pH scale?

Each universal indicator colour is given a number called the pH value.

Universal indicator can tell you the pH of a solution.

What is the pH of a weak acid? What is the pH of strong base?

weak base

weakacid

strongbase

strongacid

stronger basestronger acid

neutral

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


What is the pH?


Are these substances acidic or basene? Are they weak or strong?

1 2 14131211109876543

Substance pH Description of acid/base

soda water 6

car battery acid 1

soap 8

washing soda 10

stomach acid 2

oven cleaner 14

vinegar 4

very weak acid

very strong acid

very weak base

weak base

strong acid

very strong base

weak acid

baseacid

What type of substance?


Mixing an acid and an base

What happens when an acid and an base are mixed?

Mixing an acid and an base causes a chemical change.

This chemical change is called a chemical reaction.

How do you know this chemical reaction has taken place?

?


What is neutralization?

The chemical reaction between an acid and an base is called neutralization.

What happens to the pH value of the reaction mixture during neutralization?

acid base a salt water

The pH value of the reaction mixture becomes closer to 7.

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© Boardworks Ltd 2004 1 of 20 © Boardworks Ltd 2004 1 of 34 What is an acid? Acids are a group of chemicals. What do you know about acids? Are all acids