Section 11 - States of Matter and Mixtures 5.0 / 5 based on 1 rating ? ScienceChemistryGCSEEdexcel Created by: ineedtorevise12Created on: 23-04-18 18:28 What is a physical change? When a substance changes from one state of matter to another. 1 of 30 What happens when a solid is heated? The particles vibrate more, which weakens the forces that hold the solid together. This makes it expand. 2 of 30 What happens when a solid melts? When they reach a certain temperature, the particles have enough energy to break free from their positions, so the solid turns into a liquid. 3 of 30 What happens when a liquid evaporates? The particles gain even more energy so they move faster, and they weaken and break their bonds. 4 of 30 What is sublimation? When a solid turns into a gas. 5 of 30 What happens in a chemical reaction? Chemical changes - when bonds between atoms break and the atoms change places. Reactants are re-arranged to form products. 6 of 30 What does it mean if a substance is pure? It is made up of a single element or compound. 7 of 30 What is a mixture? A substance with more than one compound presemt, or different elements which aren't all part of a single compound. 8 of 30 Is air a compound, mixture or pure? Why? It is a mixture as it consists of several different elements, such as oxygen, nitrogen, carbon dioxide, water vapour, etc. 9 of 30 How can you test if a substance is pure? By comparing the actual melting point of a sample of a substance to the expected value. Impure substances will melt over a rang of temperatures. 10 of 30 What is filtration used for? To separate an insoluble solid from a liquid. 11 of 30 What is crystallisation used for? To separate a soluble solid from a solution. 12 of 30 What are the two phases in chromatography? Stationary phase and mobile phase? 13 of 30 What is the mobile phase? Where the molecules can move. The solvent (water/ethanol). 14 of 30 What is the stationary phase? Where the molecules can't move. The filter paper. 15 of 30 How do you work out the Rf value? Distance travelled by solute divided by distance travelled by solvent. 16 of 30 Why do you draw the line near the bottom of the paper using a pencil? Because it's insoluble and won't move with the solvent. 17 of 30 The amount of time the molecules spend in each phase depends on what? 1) How soluble they are in the solvent. 2) How attracted they are to the stationary phase. 18 of 30 If the chemicals in your mixture are colourless (e.g. amino acids), what do you do? You spray the chromatogram with a locating agent to show where the spots are. 19 of 30 What is the Rf value? The ratio between the distance travelled by the dissolved substance and the solvent. 20 of 30 Where do we get our water from? Surface water, ground water and waste water. 21 of 30 Through what processes is water purified? Filtration, sedimentation and chorination. 22 of 30 How does filtration purify water? A wire mesh screens out large twigs and then gravel and sand beds filter out any other solid bits. 23 of 30 How does sedimentation purify water? Iron sulfate or aluminium sulfate is added to the water, which makes fine particles clump together and settle at the bottom. 24 of 30 How does chlorination purify water? Chlorine gas is bubbled through to kill harmful bacteria and other microbes. 25 of 30 How else can you get potable water? By distilling sea water. 26 of 30 Why isn't sea water distilled in the UK? Because it requires lots of energy so it is very expensive. 27 of 30 What kind of water should be used in chemical analysis? Deionised water. 28 of 30 What is deionised water? Water that has had the ions (calcium, iron and copper ions) that are present in normal tap water removed. 29 of 30 Why is deionised water used? Because the ions can interfere with reactions and give the experiment a false result. 30 of 30
EDEXCEL GCSE 9-1 COMBINED SCIENCE FOUNDATION PAPER 3 CHEMISTRY 1 QUESTION PAPER SAMPLE ASSESSMENT MATERIAL 0.0 / 5
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