Chemical quantities (AS)
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I am doing a titration experiment on finding the concentration of sulphuric acid which will be between 0.05 and 0.15 mol dm-3, using anhydrous sodium carbonate (dissolved in distilled water) and as an indicator methyl orange... However I am uncertain of the amounts of each substance to use. Could you possibly recommend some guidelines for me to follow.
At the moment I am thinking of using 5 g of sodium carbonate but I'm still unsure of how much sulphuric acid and distilled water to use.
Corrie writes
Let's assume you would like a burette reading of around 25 cm3 of acid in your titration. Let's also assume, for the moment, your acid is 0.10 M, the middle of your range above. Work out how many moles of sulphuric acid this volume would contain.
From the balanced equation for the reaction you should know the ratio in which the carbonate and acid react is 1:1. So now you know how many moles, and hence the mass, of sodium carbonate to weigh out and put in your titration flask, to achieve a reasonable titration volume. Do you think the volume of water added to dissolve the carbonate will affect the titration value? (Hint: will the number of moles of sodium carbonate in the flask change if water is added?)
Since the acid's concentration is actually somewhere between 0.05 and 0.15 M, your real titration value should be somewhere between 12.5 and 37.5 cm3 - a perfectly respectable working range.
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updated: 20 August 2007
