Embedded Files
Purify and Test Water
Background Information and Keywords
Background Information and Keywords
Keywords
Keywords
- Soluble - When a substance can be dissolved in the solvent
- Insoluble - When a substance cannot be dissolved in the solvent
- Solution - When a solute is dissolved in a solvent
- Dissolve - the action, when a solid substance has been added to a solvent/water and broken up so it can no longer be seen by the eye.
- Potable Water - water that is safe for us to drink
- Pure Water - water that contains no dissolved solids. It is just water molecules
Background Information
Background Information
This practical is all about trying to work out if water is pure or not.
Water can be described as pure and potable.
Water is vital for life on Earth to survive, so it's vital we know if water is safe to drink and what's in it.
As water is colourless and a lot of things dissolve in it easily, it can be hard to tell just by looking what might be in the water. Is it safe to drink?
This practical is all about working out if there are impurities in the water, and how to get rid of them so it's safe for us to drink.
Other things you need to be able to do
Other things you need to be able to do
To do the practical
To do the practical
To know what universal indicator is and the different colours it goes
To be able to measure the pH of a substance
To be able to accurately weigh the mass of pieces of equipment
To be able to accurately measure volumes of liquids
To be able to measure the boiling point of a substance
To handle the data and make conclusions
To handle the data and make conclusions
To be able to use your knowledge of these tests to decide if a water sample is pure or not
To be able to calculate the mass of solute using the "mass by difference" method
To be able to describe how distillation can be used to purify water
"How To Do It" Video
"How To Do It" Video
Watch this video to remind yourself how the practical in this PAG are carried out.
What are the key steps?
What are the key chemicals called to test if the water is pure?
How is the water purified?
Diagrams
Diagrams
Practical 1: Testing pH of the water
Practical 1: Testing pH of the water
Key Steps
Key Steps
Place a small sample of the water you want to test in a test tube.
Add a small amount of universal indicator solution to the test tube OR dip a piece of universal indicator paper in it
Compare the colour of the pH paper to a pH colour scale to decide what pH value the water has.
Practical 2: Finding if the water contains dissolved solids
Practical 2: Finding if the water contains dissolved solids
Key Steps
Key Steps
Weigh an empty watch glass on a pair of scales. Record how much the watch glass weighs.
Measure out about 4cm3 of the water sample using a measuring cylinder.
Pour the water onto the watch glass and place the watch glass on top of a beaker of water over a bunsen burner. This set up allows the water in the watch glass to be heated gently so it won't bubble and spill and the glass won't break.
Heat the water until all the water has evaporated. On the watch glass there will be a residue of any dissolved solids which are left behind.
Place the watch glass on the scales again and reweigh. You will find the watch glass is heavier.
Take away the initial weight of the glass from the final weight to find the mass of the dissolved solids.
Practical 3: Purifying the water using simple distillation
Practical 3: Purifying the water using simple distillation
Key Steps
Key Steps
Place the impure water (e.g. salt water) in a flask.
Attach the flask to a condenser tube and place a conical flask to collect the water at the end of the condenser.
Attach the hose of the condenser to a tap and turn on the water (this will cool down the condenser tube).
Place a bunsen burner under the impure water and heat. The water will boil/evaporate leaving behind the dissolved solids.
The water cools and condenses. The water will flow down and collect in the conical flask.
Key Questions from this Practical
Key Questions from this Practical
What is a simple physical test you can do to see if a sample of water is pure?
What is the pH of pure water?
Describe a practical you could use to turn salt water into drinking water.
Describe a practical you could do to calculate the mass of dissolved solids in a sample of water.
Question Practice and Exam Questions
Question Practice and Exam Questions
Required Practicals Mastery Booklet - PAG 8 - Purifying Water.pdfPAG 8: Mastery Question Booklet
PAG 8: Mastery Question Booklet
This Mastery Booklet is filled with questions and exam questions to help you master this core practical. All answers and mark schemes are attached at the end.
Report abuse