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39 Cards in this Set
- Front
- Back
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How to test the purity of a sample |
-Measure it's melting or boiling point -Compare it to the pure substance (found in a data book) -The closer it is, the purer the sample is |
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Melting point of a substance with impurities |
-Lower than original -Higher range |
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Boiling point of a substance with impurities |
-Higher than original -May boil at a range of tempretures |
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What are formulations |
-Useful mixtures with a precise formula -Each component present in a measured quantity and contributes to properties so it meets function |
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6 every - day uses of formulations |
-Cleaning products -Fuels -Cosmetics -Fertilisers -Metal alloys -Food and drink |
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How to test for carbonates |
-Add dilute acid to solution -Connect tube to lime water -If carbonates present then lime water turns cloudy |
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Formula of carbonates |
2- CO3 |
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Formula of sulfates |
2- SO4 |
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How to test for sulfates |
-Add a couple of drops of dilute hydrochloric acid to solution -Add barium chloride -If sulfate ions present a white precipitate will form (Barium sulfate) |
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How to test for halides |
-Add dilute nitric acid -Add silver nitrate solution -Observe colour of precipitate |
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Colour of chloride precipitate |
White |
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Colour of bromide precipitate |
Cream |
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Colour of iodide precipitate |
Yellow |
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3 substances which can be tested for which are anions |
-Carbonates -Sulfates -Halides |
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Flame colour of sodium |
Yellow |
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Flame colour of lithium |
Crimson |
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Flame colour of potassium |
Lilac |
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Flame colour of calcium |
Orange-red |
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Flame colour of copper |
Green |
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How to perform a flame test |
-Dip a clean platinum wire into dilute HCl -Hold the wire in a blue flame until it burns without any colour -Dip wire into sample and put on flame -Observe colour of flame |
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How to test for cations by making them into a precipitate |
-Add sodium hydroxide -Observe colour of precipitate |
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Colour of calcium precipitate |
White |
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Colour of copper (II) precipitate |
Blue |
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Colour of iron (II) precipitate |
Green |
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Colour of iron (III) precipitate |
Brown |
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Colour of aluminium precipitate |
White then colourless (redissolves) |
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Colour of magnesium precipitate |
White |
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2 tests for cations |
-Flame tests -NaOH coloured precipitate |
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Ionic equation for aluminium and sodium hydroxide |
3+ - Al + 3OH 》Al (OH)3 (aq) (aq) (s) |
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What does the line spectrum depend on |
-Charge -Electron arrangement |
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What does the intensity of a line spectrum indicate |
The concentration of the ion in the solution |
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Why is flame emission spectroscopy more useful than flame tests |
It can identify different ions in mixtures |
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Advantages of instrumental analysis |
-Very sensitive -Very fast -Very accurate |
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The two phases of chromotagraphy |
-Mobile phase - Molecules can move -Stationary phase - Molecules can't move |
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What is the mobile phase in chromatography |
A stage where molecules can move. Always a liquid or a gas |
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What is the stationary phase in chromotagraphy |
A stage where molecules can't move. Can be a solid or a really thick liquid |
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What does how quickly a chemical moves in chromatography depend on |
-How it's distributed between the two phases, where the equilibrium is -If more time in mobile phase then it will move further in the stationary phase |
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In paper chromatography what does the time the molecules spend in each phase depend on |
-How soluble the are in the solvent -How attracted the are to the paper |
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How to tell if a compound is present in a mixture using chromotagraphy |
-Put mixture in a solvent and compere Rf value with reference -Repeat with different solvents -If they match then it is likely they are the same |
