Organic 2 Review Problem 478

Organic 2 Review Problem 478 - 4 62 P RACTICAL O RGANIC C...

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462 PRACTICAL ORGANIC CHEMISTRY ESTIMATION OF GLUCOSE IN A GIVEN SAMPLE. This is clearly the reverse of the standardisation of the Fehling's solution described above. Weigh out accurately about 1-25 g. of the sample, dissolve it in water and make the solution up to 250 ml. Titrate this solution against 25 ml. of the standard Fehling's solution, precisely as before. Example of Calculation. Weight of sample taken, i -250 g. Dissolved in 250 ml. of water. 25 ml. of Fehling's solution required 26-7 ml. of glucose solution. But i ml. of Fehling's solution = 0-005 g. of pure glucose, i.e., 26*7 ml. of glucose solution contain 25 X 0-005 g- °f pure glucose. , r . . . . 25 x 0-005 x 250 .. 250 ml. of glucose solution contain g. pure glucose 26-7 . 0 . . 25 X 0-005 x 250 x ioo . . Sample contains % of pure glucose 26-7 X 1-250 = 93'7% glucose. ESTIMATION OF CANE SUGAR (SUCROSE). This is done by estimating the reducing power of the sugar after hydrolysis (or "inversion") by acid, the glucose and fructose thus formed having very
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.

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