C12, Chemical Analysis. 5.0 / 5 based on 3 ratings ? ChemistryAnalysing substancesGCSEAQA Created by: cieran_10Created on: 21-09-18 23:23 What is pure substance? One made up of just a single element/compound, meaning it is not mixed with any other substance. 1 of 34 What is a pure substance in everyday life? That something has had nothing added to it or is in its natural state, such as: pure orange juice. 2 of 34 What is a test for water (but doesn't show that it is pure?) Turning white anhydrous copper sulphate to a blue colour. 3 of 34 What is the test for PURE water? If it boiling point at exactly 100 degrees and if its melting point is exactly 0 degrees. 4 of 34 Why is it that boiling and melting points can be used to measure the purity of substances? As pure substances have specific ones. 5 of 34 What are tow fixed points? The melting snd boiling points of a substance. 6 of 34 What can be said about the melting and boiling points of mixtures and why is this? That they are variable, given that the state can change over a range of different temperatures. 7 of 34 How can the difference between a pure and impure substance be found? Through the melting range of the different substances. 8 of 34 What do impurities do to the meting and boiling points of substances? They lower the melting points and raise the boiling points. 9 of 34 What is a formulation? A mixture that has been designed to produce a useful product. 10 of 34 In a formulation, why will each element have been chosen? For a certain purpose. 11 of 34 Why are the chemicals of a formulation mixed in set proportions? So that they give the required properties. 12 of 34 Give eight examples of formulations? Paint, fuel, alloys, fertilisers, cleaning agents, medicines, cosmetics and food products. 13 of 34 What three things does paint contain and why? Pigment to provide colour, binder to help the paint attach to things and a solvent to hep the pigment and binder spread well. 14 of 34 What is the mobile phase of paper chromotography? The solvent. 15 of 34 What is the stationary phase of paper chromatography? The paper. 16 of 34 What does a substance travelling further up the chromatogram show? That it has a stronger force of attraction to the solvent. 17 of 34 How many spots will a pure substance form on a chromatogram? What about a mixture? One spot. Multiple spots. 18 of 34 How can you calculate the retention factor? Distance moved by substance / distance moved by solvent. 19 of 34 What is the retention factor used for? To compare the spots on the chromatogram. 20 of 34 How can you test for hydrogen gas? Collect a tube of gas, then, hold a lit splint at the open end of the test tube and if it burns with a squeaky pop then it is hydrogen. 21 of 34 How can you test for oxygen gas? By inserting a glowing splint into the mouth of a test tube of gas and if the glowing splint relights, oxygen is present. 22 of 34 What is the test for carbon dioxide? Bubble the gas through limewater and if it turns to a cloudy white solution, carbon dioxide is present. 23 of 34 What is limewater? Calcium hydroxide solution. 24 of 34 What is the test for chlorine gas? If a piece of damp and blue litmus paper turns white/is bleached, then chlorine is present. 25 of 34 Why must you be careful when testing for chlorine gas? As it is a toxic gas. 26 of 34 What colour flame does a lithium ion produce? Crimson. 27 of 34 What colour flame does a sodium ion produce? Yellow. 28 of 34 What colour flame does a potassium ion produce? Lilac. 29 of 34 What colour flame does a calcium ion produce? Orange-red. 30 of 34 What colour flame does a copper ion produce? Green. 31 of 34 What is the general rule for hydroxides of metals with ions of 2+ and 3+ charges? That they are insoluble in water. 32 of 34 What happens when sodium hydroxide solution is added to hydroxides of metals with ions of 2+ and 3+ charges? They produce a precipitate of metal hydroxides, as they are insoluble. 33 of 34 What three ions form white precipitates of their hydroxides? Aluminium, calcium and magnesium. 34 of 34
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