8303174-59-Titration-Calculations

8303174-59-Titration-Calculations - Chem Factsheet...

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Titration Calculations: Revision Summary Number 59 1 C hem F actsheet www.curriculumpress.co.uk To succeed with this topic you need to know and understand the material covered so far in Factsheets No. 7 (Moles and Volumetric Analysis), No.23 (How to Answer Questions on Titration Calculations), No.51 (‘Redox Equilibria (IV) : Redox Titrations’) No.57: Answering questions on Redox Titrations 1) The purpose of this Factsheet is to bring together all the different types of titration calculations under various categories. By now you should be competent in titration calculations. If you can now recognise a calculation problem as belonging to a particular category it will help you to get into the problem more quickly. You should regard this Factsheet as a summary of all the four Factsheets listed above. We will re-visit the basic equations and terms, and then put in the categories. TERMS USED Volumetric analysis - this is another way of saying TITRATION i.e. adding reacting solutions together to find the exact point (the end- point) when the two solutions have completely reacted together. Standard Solution - a solution made by dissolving an accurate amount of solid in, usually, water. The volume is usually 250cm 3 so you can always calculate g dm -3 . If the M r is known, you can calculate mol dm -3 . Titre - the final volume added from the burette in the titration. When a series of titrations are done, then titres in good agreement (concordant) are averaged to give the volume used in calculations – the AVERAGE TITRE. Acid/Base Titration - as it says! An acidic solution reacting with a basic solution (neutralisation). Redox Titration - the two half equations are combined to give the balanced chemical equation (using the ‘electron balancing method’). One of the half equations is a reduction process (electron gain) and the other an oxidation process (loss of electrons) EQUATIONS USED IN CALCULATIONS moles = grams A r / M r moles = volume (cm 3 ) × M (mol dm -3 ) 1000 purity percentage = mass of pure × 100 mass of impure percentage by mass = mass of element × 100 mass of compound CATEGORIES OF TITRATION CALCULATIONS categories 1, 2, 3, 4 and 5 use examples from both redox and acid/ base titrations. category 6 is usually only acid/base titration type. 1 Finding concentration of a solution 2. Finding the formula mass ( M r ) of a compound 3. Finding the percentage purity of a sample of impure compounds 4. Finding the formula of a compound 5. Finding the percentage mass of an element in a compound 6. Using the 'back titration' method A standard solution is made and used to find the concentration of the other solution in the titration. A standard solution is made of the

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This note was uploaded on 03/08/2011 for the course CHEM 101 taught by Professor Hard during the Spring '11 term at UT Arlington.

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8303174-59-Titration-Calculations - Chem Factsheet...

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