Separation of Rock Salt

Aim: To obtain pure salt from rock salt.

Equipment: Safety Information • Sample of rock salt Hot water – risk of scalds and burns • Pestle and mortar Wear goggles, take care when • Two 250cm³ beakers heating

• Stirring rod Glassware – risk of cuts if broken

• Filter Apply pressure to wounds and inform teacher immediately • Filter papers – risk of burns • Tripod Place under cold running water for 10 minutes • Heatproof mat and inform teacher • Bunsen burner

• Evaporating basin

Method: Step 1: Carefully grind up the rock salt in the pestle and mortar.

Step 2: Stir the ground rock salt into a beaker of water to dissolve it.

Step 3: Carefully filter the solution through the in the funnel, into the second beaker.

Step 4: Transfer approximately 10ml of the filtered solution into the evaporating basin and set on the tripod over the Bunsen burner.

Page 1 of 3 Separation of Rock Salt

Step 5: Heat the water until it is gently boiling and the water begins to evaporate off.

Step 6: When crystals begin to form on the sides of the basin, turn off the Bunsen burner – you now have a saturated solution.

Step 7: Leave the equipment to cool and then move the basin to a warm place to evaporate more slowly (overnight).

Rock salt is a mixture of sand and salt. It is also sometimes called grit salt and is used on roads during winter. The sand and salt compounds have different properties and so they can be separated.

Questions: 1. In step 2, water is acting as a solvent. What is a solvent?

2. Explain how the salt water solution is separated from the sand in step 3.

3. Draw a clearly labelled diagram to show the particles of sand and salt in step 3.

4. What is meant by a saturated solution, as described in step 6?

5. Explain, in terms of energy and particle arrangement, what evaporation is.

Page 2 of 3 Separation of Rock Salt Answers:

1. In step 2, water is acting as a solvent. What is a solvent? A solvent is a substance able to dissolve other substances.

2. Explain how the salt water solution is separated from the sand in step 3. The sand grains are insoluble (unable to dissolve) and so they cannot pass through the porous filter paper with the water and are left in the .

3. Draw a clearly labelled diagram to show the particles of sand and salt in step 3.

4. What is meant by a saturated solution, as described in step 6? As much salt as possible is dissolved - no more salt can be dissolved.

5. Explain, in terms of energy and particle arrangement, what evaporation is. The water particles have gained more energy from the heating, and begin to move faster. The bonds between the water particles become weaker and some break off and become a gas particle instead. Separating Techniques A E R N D F E T H G F M C H R I A P R G N Q R I N C K S L R R H I E O C N S A E U F S N D M E V A P O R A T I O N M O P C T S D I E U C N C I O N A R U D N O I I Q I C N R T I E Q D S C N C T I E U L F S O I R I B C M E I H A O R G I E L F S D A S O I S T M I R R E G A L N A B O A E U N V N R I O O M E C R Y S T A L L I S A T I O N I M N E D E U T I S V C H I L S T S C H A W E R U N D O L I E E R D N F I R I T N F A R I O N P N P N C I N A S R I O A B D R U F B A G J F B S F I O R O G Q P N M U Y T B A N F R T D O L A L R R O P E N F I R P A B F I O E U B F A R J K L E P A N E J R P L O A B O F P N I A R O I N S O L U B L E N L T G H A N F I R O T P A N F R A I A E N F Y D C H R I S D P E I R N T C J A L R I T N D O E O Q P D N A M I O P A L S R I O P S O L V E N T N A O R I A N A M F O R P Q N D M A L O P N I A N F E L P A

Find the following words in the grid: chromatography distillation insoluble crystallisation evaporation soluble dissolving fractional distillation solvent

Task

Which separation technique would you use to:

• separate sand and salt;

• separate a mixture of dyes;

• separate crude oil;

• separate an insoluble from a liquid?

visit twinkl.com Separation Techniques - Activity Sheet Separation Techniques - Activity Sheet

Draw a line to match the separation technique used to separate the following: Draw a line to match the separation technique used to separate the following:

A mixture of sand A mixture of sand Distillation Distillation and water. and water.

Iron and Iron and Evaporation Evaporation Aluminium tins. Aluminium tins.

A sugar solution. Chromatography A sugar solution. Chromatography

A mixture of ink A mixture of ink Filtering Filtering and water. and water.

A paint sample. Magnetism A paint sample. Magnetism Distillation

Use your knowledge of changing states and scientific apparatus to note down your initial ideas on distillation. Apparatus

Bunsen burner glass beaker Round bottomed flask Tripod Separating Techniques - Distillation Use this sheet to think through what happens in distillation and write your initial ideas down, guided by the questions. Start in the bottom left hand corner and complete the boxes in a clockwise direction.

This piece of science apparatus is a… Stage 2: Cold water is pumped around this ‘tube’. What would happen to the water particles at this stage? And it is used for...

Stage 1: Inside the round bottomed flask is a mixture of ink and water. Describe what is happening to the water particles at this stage. Stage 3: Predict what comes out of the ‘tube’ into the beaker. Hint: remember this is a

separating technique!

*Start* This piece of science apparatus is a…

And it is used for...

visit twinkl.com Crystallisation Separation Technique Method

Cut out the cards below and reorganise them into the correct sequence.

Turn off the Bunsen burner.

Set the on a gauze and tripod.

Pour the solution into an evaporating dish.

Gently heat the solution until only a small amount of liquid remains.

Place the evaporating dish somewhere warm and allow the remaining liquid to evaporate overnight.

Allow the equipment to cool before handling.

Connect and light the Bunsen burner. Crystallisation Separation Technique Method

Cut out the cards below and reorganise them into the correct sequence.

Open the Bunsen burner air hole.

Gently heat the solution until only a small amount of liquid remains.

Connect a Bunsen burner.

Pour the solution into an evaporating dish.

Close the Bunsen burner air hole.

Turn off the Bunsen burner.

Allow the equipment to cool before handling.

Set the evaporating dish on a gauze and tripod.

Place the evaporating dish somewhere warm and allow the remaining liquid to evaporate overnight.

Turn on the gas and light the Bunsen burner using a lit splint. Chromatography

Chromatography separates Carotin substances in a mixture. Phaeophytin The technique relies on the substance being soluble in a solvent. Chlorophyll A The term was first used in 1906 when Russian botanist Mikhail Tsvet wrote a paper about producing a colourful Chlorophyll B pattern of plant pigments! Lutein

Violaxanthin

Neoxanthin

Photo courtesy of Flo~commonswiki, via Wikimedia Commons Chromatography

Step 1: A small amount of solution is placed in a beaker.

Step 2: On a piece of chromatography/filter paper, a pencil line is drawn.

pencil substance base to be tested line

experiment at start

Step 3: Spots of the substance are placed on the line, spaced apart. Chromatography

Step 4: The paper is placed into the beaker, with the pencil line at the bottom. Step 5: The solvent moves up the paper and the dyes begin to separate out. Step 6: The spots on the chromatogram are analysed and compared. Real World Applications

A red dye is often activated and explodes onto on large quantities of money taken from banks. The dye creates a unique chromatogram that can be compared with suspect notes.

Foods can be tested to see if they contain flavour or colour additives. Also to quantify the vitamin content. Separating Techniques Answers A E R N D F E T H G F M C H R I A P R G N Q R I N C K S L R R H I E O C N S A E U F S N D M E V A P O R A T I O N M O P C T S D I E U C N C I O N A R U D N O I I Q I C N R T I E Q D S C N C T I E U L F S O I R I B C M E I H A O R G I E L F S D A S O I S T M I R R E G A L N A B O A E U N V N R I O O M E C R Y S T A L L I S A T I O N I M N E D E U T I S V C H I L S T S C H A W E R U N D O L I E E R D N F I R I T N F A R I O N P N P N C I N A S R I O A B D R U F B A G J F B S F I O R O G Q P N M U Y T B A N F R T D O L A L R R O P E N F I R P A B F I O E U B F A R J K L E P A N E J R P L O A B O F P N I A R O I N S O L U B L E N L T G H A N F I R O T P A N F R A I A E N F Y D C H R I S D P E I R N T C J A L R I T N D O E O Q P D N A M I O P A L S R I O P S O L V E N T N A O R I A N A M F O R P Q N D M A L O P N I A N F E L P A

Task

Which separation technique would you use to:

• separate sand and salt; filtration and evaporation

• separate a mixture of dyes; chromatography

• separate crude oil; fractional distillation

• separate an insoluble from a liquid? filtration

visit twinkl.com Separation Techniques - Activity Sheet Answers

Draw a line to match the separation technique used to separate the following:

A mixture of sand and water. Distillation

Iron and Aluminium tins. Evaporation

A sugar solution. Chromatography

A mixture of ink and water. Filtering

A paint sample. Magnetism Crystallisation Separation Technique Method (Answers)

Pour the solution into an evaporating dish.

Set the evaporating dish on a gauze and tripod.

Connect and light the Bunsen burner.

Gently heat the solution until only a small amount of liquid remains.

Turn off the Bunsen burner.

Allow the equipment to cool before handling.

Place the evaporating dish somewhere warm and allow the remaining liquid to evaporate overnight. Crystallisation Separation Technique Method (Answers)

Pour the solution into an evaporating dish.

Set the evaporating dish on a gauze and tripod.

Connect a Bunsen burner.

Close the Bunsen burner air hole.

Turn on the gas and light the Bunsen burner using a lit splint.

Open the Bunsen burner air hole.

Gently heat the solution until only a small amount of liquid remains.

Turn off the Bunsen burner.

Allow the equipment to cool before handling.

Place the evaporating dish somewhere warm and allow the remaining liquid to evaporate overnight.