3.6-8 chemistry 3.0 / 5 based on 1 rating ? ChemistryGCSEAQA Created by: Rebecca WalmsleyCreated on: 23-04-13 20:40 what is a reversible reaction? a reaction that can go both forwards and backwards, or both ways, or in both directions 1 of 30 what happens in a reversible reaction? the products of the reaction can react to make the original reactants 2 of 30 eg of reversible reaction? thermal decomposition of ammonium chloride 3 of 30 what dioes ammonium chloride form when heated? decomposes to form ammonia and hydrogen chloride. 4 of 30 what happens when it cools? ammonia and hydrogen chloride react to form ammonium chloride 5 of 30 what are food additives? substances added to food to improve its qualities. 6 of 30 what may food additives be? natural products; synthetic chemicals 7 of 30 foods can be checked by what? chemical analysis 8 of 30 why? to ensure only safe permitted additives have been used 9 of 30 what do these types of methods include? paper chromatography and mass chromatogrophy 10 of 30 what can paper chromotography be used for? analysing artificial colours in foods 11 of 30 describe paper chromatography a spot of colour is but onto the paper and solvent is allowed to move through the paper 12 of 30 what do different distances depend on? the solubilty of the colours 13 of 30 what do modern instrumental techniques provide? fast, accurate and sensitive ways of analysing chemical substances 14 of 30 what can seperate compounds in a mixture gas chromatography 15 of 30 how can be identified once seperated? using mass spectrometer 16 of 30 what does it find? relative molecular mass of a compound from its molecular ion peak 17 of 30 what are samples needed to be used for analysis? mixtures that need to be seperated 18 of 30 why do they need to be seperated so that compunds can be identfied 19 of 30 how would one go about doing this? use gas chromatography 20 of 30 what is mixture carried by in gas chromatography? gas 21 of 30 what does it go through? a long column packed with solid particles 22 of 30 what do the individual compounds do? travel at different speeds through the column and come out at different times 23 of 30 what does recording the amount of substance leaving the column against time show? the number of compounds in a mixture and their retention time 24 of 30 how does the retention time help? can be compared with results of other known compunds to help identify the compounds in a mixture 25 of 30 what can the output from gas chromatography be directly linked to? mass spectrometer 26 of 30 what does it give? further data, can be used quickly to identify the individual compounds 27 of 30 for an individual compound the peak with the largest mass coresponds to.. an ion with just one electron removed 28 of 30 what is the peak called? molecular ion peak 29 of 30 how is it represented on a mass spectrum furthest to the right 30 of 30
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