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Hazardous Substances

In this worksheet, students will look at the dangers associated with acids and alkalis and the hazard symbols associated with them.

'Hazardous Substances' worksheet

Key stage:  KS 3

Curriculum topic:   Chemistry: Chemical Reactions

Curriculum subtopic:   Acids and Alkalis: Neutralisation Reactions

Difficulty level:  

Worksheet Overview

QUESTION 1 of 10

Your home contains a variety of substances that are acidic, such as vinegar, fizzy pop and lemon juice, but they are only weakly acidic and therefore harmless. Your home also contains weak alkalis such as bicarbonate of soda and milk which are also harmless.

 

However stronger acids such as hydrochloric acid and alkalis such as sodium hydroxide that are found mostly in science labs, must have a hazard symbol on their packaging to warn people of the dangers of the chemical they are using.

 

Harmful hazard symbolThis is the symbol for harmful. If the symbol has a small letter 'h' next to it, it signifies that the substance is harmful, similar to a toxic substance but less dangerous.

A small letter 'i' next to the symbol indicates that the substance is an irritant and can damage the skin or lungs.

 

 

Corrosive hazard symbol

 

This is the symbol for corrosive. Corrosive substances attack and destroy living tissue including the skin and eyes.

 

 

 

 

When chemicals are transported by road, the vehicles carrying the chemicals must display the appropriate hazard-warning sign. These signs inform the emergency services of what chemical is being carried and how it should be dealt with.

 

If large amounts of acid are released, the fire brigade would add lots of water to dilute the acid and make it less harmful.

    What hazard is represented by the following symbol (look carefully!)?

 

Irritant hazard symbol i

 

    

harmful (irritant)

harmful (harmful)

corrosive

    What hazard is represented by the following symbol?

 

Harmful hazard symbol h

 

    

harmful (irritant)

harmful (harmful)

corrosive

What hazard is represented by the following symbol? 

harmful (irritant)

harmful (harmful)

corrosive

Tick the substances below that should carry a hazard symbol.

Hydrochloric acid

Vinegar

Sodium hydroxide

Lemon juice

Bicarbonate of soda

Battery acid

If battery acid from a car battery is spilled on the floor of a garage, what would be the best substance to add to the spillage to reduce the risk of injury?

Hydrochloric acid

Sodium hydroxide

Water

Concentrated sodium hydroxide is spilled onto the floor of a science lab.

 

Which of the following should be added to it before it is cleaned up?

Hydrochloric acid

Sodium hydroxide

Water

Which of the following should be worn when dealing with strong acids or alkalis that carry hazard symbols?

Safety goggles

Hard hat

Rubber gloves

Protective clothing

Ear plugs

Tick the words below that best describe a concentrated solution of sulfuric acid.

Corrosive

Harmful

Radioactive

Oxidising

Flammable

Which of the following symbols would you not expect to see on a bottle of concentrated sodium hydroxide?

 

Hazard Symbol 1 Hazard Symbol 2 Hazard Symbol 3
Hazard Symbol 1

Hazard Symbol 2

Hazard Symbol 3

Using the table below, decide which of the substances are acids and which are alkalis.

 AcidAlkali
Hydrochloric acid
Vinegar
Bicarbonate of soda
Lemon juice
Sodium hydroxide
Fizzy pop
  • Question 1

    What hazard is represented by the following symbol (look carefully!)?

 

Irritant hazard symbol i

 

    

CORRECT ANSWER
harmful (irritant)
EDDIE SAYS
The small letter 'i' next to the harmful symbol indicates that it is an irritant.
  • Question 2

    What hazard is represented by the following symbol?

 

Harmful hazard symbol h

 

    

CORRECT ANSWER
harmful (harmful)
EDDIE SAYS
The small letter 'h' next to the harmful symbol indicates that it is a harmful substance.
  • Question 3

What hazard is represented by the following symbol? 

CORRECT ANSWER
corrosive
EDDIE SAYS
Acids are corrosive and can damage tissue if they are strong acids.
  • Question 4

Tick the substances below that should carry a hazard symbol.

CORRECT ANSWER
Hydrochloric acid
Sodium hydroxide
Battery acid
EDDIE SAYS
Stong acids such as hydrochloric acid or battery acid, and strong alkalis such as sodium hydroxide (caustic soda) should always carry the appropriate hazard symbol. To some extent, if you find it in your food cupboard, it probably doesn't need a hazard label (unless it's the product of one of your experiments!).
  • Question 5

If battery acid from a car battery is spilled on the floor of a garage, what would be the best substance to add to the spillage to reduce the risk of injury?

CORRECT ANSWER
Water
EDDIE SAYS
Only water should be added to an acid spillage as it will dilute the acid. Adding an alkali such as sodium hydroxide may result in the solution becoming alkaline which can be just as dangerous.
  • Question 6

Concentrated sodium hydroxide is spilled onto the floor of a science lab.

 

Which of the following should be added to it before it is cleaned up?

CORRECT ANSWER
Water
EDDIE SAYS
Only water should be added to an alkali spillage as it will dilute the alkali. If you add a strong acid, you increase the hazard: handling the acid is potentially dangerous, as is pouring it on to the floor, it will react with the spilt alkali and produce heat and, if you add too much, you'll now have an excess of acid on the floor! Much better just to use water to dilute it. Much safer!
  • Question 7

Which of the following should be worn when dealing with strong acids or alkalis that carry hazard symbols?

CORRECT ANSWER
Safety goggles
Rubber gloves
Protective clothing
EDDIE SAYS
Safety goggles, gloves and protective clothing such as a lab coat should always be worn when handling strong acids and alkalis.
  • Question 8

Tick the words below that best describe a concentrated solution of sulfuric acid.

CORRECT ANSWER
Corrosive
Harmful
EDDIE SAYS
Both acids and alkalis are described as harmful and corrosive.
  • Question 9

Which of the following symbols would you not expect to see on a bottle of concentrated sodium hydroxide?

 

Hazard Symbol 1 Hazard Symbol 2 Hazard Symbol 3
CORRECT ANSWER
Hazard Symbol 3
EDDIE SAYS
Hazard symbol 3 is the hazard sign for an oxidising agent and would not be used on a bottle of sodium hydroxide. It's definitely worth getting to know these hazard symbols - one day, it might save your life!
  • Question 10

Using the table below, decide which of the substances are acids and which are alkalis.

CORRECT ANSWER
 AcidAlkali
Hydrochloric acid
Vinegar
Bicarbonate of soda
Lemon juice
Sodium hydroxide
Fizzy pop
EDDIE SAYS
The information at the start of this worksheet categorises all the substances in the table as being an acid or an alkali. Hopefully, as you learn more and more about your world, this sort of knowledge is easier to access.
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