CherrieBaby
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Posts: 91
Registered: 4-3-2005
Location: London
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Fehling's and cupritartrate?
What is the nature of the cupritartrate complex created when using Fehling's solution? How many moles of Tartrate are needed per mole of Cu(II)? I've
noticed that recipes for Fehling's have a ration of Cu(II):tartrate of about 1:4.50 (but ratio of Cu(II):NaOH between 1:9 and 1:14). Am I to assume
that there are 4 moles of tartrate per mole of Cu(II) or is it that the solution must have tartrate in excess in order for cupritartrate to
predominate?
Finally is potassium needed for the cupritartrate? Is that why Rochelle's salt is used rather than tartaric acid?
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akre
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Posts: 16
Registered: 19-1-2004
Location: Sweden
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I believe you need 2mole tartrate per mole Cu. You can use tartaric acid, I've made benedict's solution with citric acid instead of sodium citrate...
The acid is reacted with the sodium hydroxide anyways.
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