Flashcards
Chemistry Topic 2
Cards in this deck (25)
- 1When a substance is pure what does it mean?It’s completely made up of a single element or compound
- 2How can you test for purity?Using melting points
- 3How can you test the purity using melting points?Comparing the actual melting point of the sample to the expected melting point
- 4What type of substance will melt gradually over a range of temperatures?Impure and Mixtures
- 5What is distillation used for?To separate mixtures that contain liquids
- 6What is simple distillation used for?Separating out a liquid from a solution
- 7How do you use simple distillation to get pure water from seawater?Pour your sample of seawater into the distillation flask
Set up the apparatus. Connect the bottom end of the condenser to a cold tap using rubber tubing. Run cold water through the condenser to keep it cool
Gradually heat the distillation flask
Water vapour passes into the condenser where it cools and condenser in then flows back into the beaker where it is collected
Eventually you’ll end up with just salt in the flask - 8What is a problem with simple distillation?You can only use it to separate things with very different boiling points
- 9If you have a mixture and of liquids with similar boiling points, what type of distillation do you use?Fractional Distillation
- 10How do you complete fractional distillation?Put your mixture in a flask. Attach a fractioning column and condenser above the flask.
Gradually heat the flask.
The liquid with lowest boiling point evaporates first. When the temperature of the thermometer matches the boiling point of this liquid it will reach the top of the column.
When the first liquid has been collected raise the temperature until the next one reaches the top - 11What is filtration?It is used to separate an insoluble solid from a liquid
- 12Flirtation MethodPop some filter paper into a funnel and pour your mixture into it. The liquid part of the mixture runs through the paper, leaving behind a solid residue
- 13What does crystallisation do?Separates a soluble solid from a solution
- 14How do you crystallise a product?Pour solution into an evaporating dish and gently heat the solution
Once some of the water has evaporated or when you see crystals start to form remove the dish from the heat and leave solution to cool
The salt should start to from crystals as it becomes insoluble in the cold
Filter the crystals out of the solution and leave them in a warm place to dry - 15What is chromatography used to separate?A mixture of soluble substances
- 16What are the two phases of chromatography?Mobile Phase
And
Stationary Phase - 17What is the mobile phase?Where the molecules can move. This is always a liquid or a gas
- 18What is the stationary phase?Where the molecules can’t move. This can be a solid or a really thick liquid
- 193 examples of where we get our water fromSurface Water, Ground Water and Waste Water
- 20Where does surface water come from?Lakes, rivers and reservoirs
- 21Where does ground water come from?Aquifers - rocks that trap water underground
- 22Where does waste water come from?Water that’s been contaminated by a human process
- 23What purifies water?Water treatment plants
- 24What is the process of a water treatment plant?-Filtration - a wire mesh screens out large twigs and then gravel and sand beds filter out any other solids
-Sedimentation -iron sulfate or aluminium sulfate is added to the water which makes fine particles clump together and settle and the bottom
-chlorination - chlorine gas is bubbles through to kill harmful bacteria and other microbes - 25How can you get potable water?Distilling sea water
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- Flashcards on Chemistry Topic 2, created by Harry Smith on 26/11/2018.
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- Harry Smith
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