Difference between revisions of "Benedict's reagent"
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==Reagent== | ==Reagent== | ||
| − | The reagent is prepared by dissolving 100 g of anhydrous [[sodium carbonate]], 173 g of [[trisodium citrate]] dihydrate and 17.3 g of [[copper(II) sulfate]] pentahydrate in water, and diluting to 1 litre. The final solution is 71.3 mmol/dm<sup>3</sup> in copper(II) and 588 mmol/dm<sup>3</sup> in total citrate (eightfold excess). The copper(II) is believed to be present as a 1:1 citrate [[complex]], [Cu(C<sub>6</sub>H<sub>5</sub>O<sub>7</sub>)(OH)(H<sub>2</sub>O)<sub>''n''</sub>]<sup>2-</sup> (''n'' = 0, 1).<ref>{{citation | first1 = Terrence B. | last1 = Field | first2 = Janet L. | last2 = McCourt | first3 = W. A. E. McBryde | title = Composition and Stability of Iron and Copper Citrate Complexes in Aqueous Solution | journal = Can. J. Chem. | year = 1974 | volume = 52 | pages = 3119–24}}.</ref> | + | The reagent is prepared by dissolving 100 g of anhydrous [[sodium carbonate]], 173 g of [[trisodium citrate]] dihydrate and 17.3 g of [[copper(II) sulfate]] pentahydrate in water, and diluting to 1 litre. The final solution is 71.3 mmol/dm<sup>3</sup> in copper(II) and 588 mmol/dm<sup>3</sup> in total citrate (eightfold excess). The copper(II) is believed to be present as a 1:1 citrate [[complex]], [Cu(C<sub>6</sub>H<sub>5</sub>O<sub>7</sub>)(OH)(H<sub>2</sub>O)<sub>''n''</sub>]<sup>2-</sup> (''n'' = 0, 1).<ref>{{citation | first1 = Terrence B. | last1 = Field | first2 = Janet L. | last2 = McCourt | first3 = W. A. E. McBryde | title = Composition and Stability of Iron and Copper Citrate Complexes in Aqueous Solution | url = http://article.pubs.nrc-cnrc.gc.ca/ppv/RPViewDoc?issn=1480-3291&volume=52&issue=17&startPage=3119 | journal = Can. J. Chem. | year = 1974 | volume = 52 | pages = 3119–24}}.</ref> |
==References== | ==References== | ||
Revision as of 10:40, 7 April 2010
Benedict's reagent, also called Benedict's solution, is a reagent used to test for reducing sugars, named after American chemist Stanley Rossiter Benedict. Similar to Fehling's solution, it is an alkaline solution of copper(II) stabilized by citrate ions.
Reagent
The reagent is prepared by dissolving 100 g of anhydrous sodium carbonate, 173 g of trisodium citrate dihydrate and 17.3 g of copper(II) sulfate pentahydrate in water, and diluting to 1 litre. The final solution is 71.3 mmol/dm3 in copper(II) and 588 mmol/dm3 in total citrate (eightfold excess). The copper(II) is believed to be present as a 1:1 citrate complex, [Cu(C6H5O7)(OH)(H2O)n]2- (n = 0, 1).[1]
References
- ↑ Field, Terrence B.; McCourt, Janet L. Composition and Stability of Iron and Copper Citrate Complexes in Aqueous Solution. Can. J. Chem. 1974, 52, 3119–24, <http://article.pubs.nrc-cnrc.gc.ca/ppv/RPViewDoc?issn=1480-3291&volume=52&issue=17&startPage=3119>.
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