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Salt

In this worksheet, students will learn about salt from the sea and the ground, how it is extracted and what it is used for.

'Salt' worksheet

Key stage:  KS 3

Curriculum topic:  Chemistry: Pure and Impure Substances

Curriculum subtopic:  Separating Mixtures

Difficulty level:  

Worksheet Overview

QUESTION 1 of 10

If we let different samples of water evaporate, various chemicals will be left behind. These chemicals are called salts. One of them is the common table salt, but there are different types of salts.

 

Chemists test water samples in the laboratory to make sure they meet quality standards set by the government in order to ensure drinking water is safe. Hard water is found in some parts of the country; it contains chemicals that prevent soap from making foam. Water that does not contain these chemicals is called soft water. Hard water can damage appliances, like kettles and washing machines (see photograph below).

 

Scale on kettle element

 

Salt is obtained from sea water by letting the Sun's heat evaporate the water. The chemical name for common salt is sodium chloride. The photograph below shows a worker in a salt extraction area.

 


Extracting salt

 

 

Salt can also be obtained from rocks by mining or by pumping water into the ground. The water dissolves the salt making brine, i.e. salt solution. The brine is pumped back to the surface and heated to evaporate the water. The photograph shows rock salt.


Rock salt

Salts are important for a healthy diet and for preserving food. Salt used to be very valuable in the Roman Empire. 

What types of chemicals are dissolved in water?

Tick two uses of salt.

It gives taste to food.

It is used to clean food.

It is used in medicine.

It is used to preserve food.

It is used as fuel.

Why is water tested in laboratories?

Tick three options.

to determine which one tastes better

to determine if it is safe to drink

to identify any chemicals it contains

to determine which sample to use for cleaning

to ensure it meets quality standards

Fill in the missing word in this sentence:

to determine which one tastes better

to determine if it is safe to drink

to identify any chemicals it contains

to determine which sample to use for cleaning

to ensure it meets quality standards

Complete this sentence.

Water that does not contain chemicals that prevent soap making foam is called _______ water.

hard

soft

silky

Why do some people use water softeners to remove the chemicals that cause hard water?

It is expensive to use hard water.

It makes the water less safe.

Hard water damages appliances.

What is the chemical name for table salt?

sodium bromide

potassium chloride

sodium chloride

Name two methods of obtaining salt.

evaporating sea water

extracting brine

mining rock salt

heating hard water

analysing soft water

What happens when water is pumped into the ground during salt extraction?

Salt is dissolved, making brine.

Salt is collected.

Scum is formed.

A student investigates the salt content of three different samples of water by pouring the samples into containers and then letting the water evaporate. The mass of the salt left behind is measured in order to compare the salt quantities of the samples.

 

What variable must be kept the same, so that the results are accurate?

salt quantity

water quantity

size of beaker

  • Question 1

What types of chemicals are dissolved in water?

CORRECT ANSWER
salt
salts
EDDIE SAYS
Various chemicals are dissolved in different samples of water. All these chemicals are salts.
  • Question 2

Tick two uses of salt.

CORRECT ANSWER
It gives taste to food.
It is used to preserve food.
EDDIE SAYS
Salt is added to food to make it taste better and to preserve it.
  • Question 3

Why is water tested in laboratories?

Tick three options.

CORRECT ANSWER
to determine if it is safe to drink
to identify any chemicals it contains
to ensure it meets quality standards
EDDIE SAYS
Drinking water is tested in laboratories to identify any chemicals it contains and determine if it is safe. This is part of adhering to quality standards set by the government.
  • Question 4

Fill in the missing word in this sentence:

CORRECT ANSWER
EDDIE SAYS
Hard water contains chemicals that prevent soap from making foam. These chemicals also cause a build-up of limescale inside appliances like kettles and washing machines. This can damage them.
  • Question 5

Complete this sentence.

Water that does not contain chemicals that prevent soap making foam is called _______ water.

CORRECT ANSWER
soft
EDDIE SAYS
Water that does not contain chemicals that prevent soap making foam is called soft water.
  • Question 6

Why do some people use water softeners to remove the chemicals that cause hard water?

CORRECT ANSWER
Hard water damages appliances.
EDDIE SAYS
Water softener is used to remove chemicals that cause hard water; these chemicals damage appliances, so owners try to ensure that their appliances will remain in a good condition for as long as possible.
  • Question 7

What is the chemical name for table salt?

CORRECT ANSWER
sodium chloride
EDDIE SAYS
Table salt is chemically known as sodium chloride.
  • Question 8

Name two methods of obtaining salt.

CORRECT ANSWER
evaporating sea water
mining rock salt
EDDIE SAYS
Salt can be obtained by evaporating sea water and mining rock salt.
Brine is also used to obtain salt from rocks, but brine is made by humans, not extracted. Salt is extracted.
  • Question 9

What happens when water is pumped into the ground during salt extraction?

CORRECT ANSWER
Salt is dissolved, making brine.
EDDIE SAYS
Salt from rocks can be removed by pumping water into the ground. This dissolves the salt, making brine. Brine is pumped back to the surface and heated to evaporate the water.
  • Question 10

A student investigates the salt content of three different samples of water by pouring the samples into containers and then letting the water evaporate. The mass of the salt left behind is measured in order to compare the salt quantities of the samples.

 

What variable must be kept the same, so that the results are accurate?

CORRECT ANSWER
water quantity
EDDIE SAYS
Ideally, all equipment used for this experiment must be kept the same and the same method used to evaporate each sample. However, it is imperative that the amount of each sample is kept the same, otherwise the amount of salt left behind cannot be compared accurately.
---- OR ----

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