A sample advertised as pure fructose obtained at a health food store, is analyzed as follows: a 22.5 gram sample is dissolved in 50.0 mL distilled water and the solution is allowed to slowly equilibrate for one hour. It is then placed in a 1dm tube in a polarimeter at 20 degree C. The observed rotation is -41.4 degrees. Calcultae the specific rotaion. Consult the following specific rotations for common carbohydrates and decide if the commericial sample is pure fructose.
Specific rotations: D-Ribose-23.7, L-Arabinose +104.5, D-Xylose +19.0, D-Glucose +52.2, D-Galactose +80.5, D-Mannose +14.6, D-fructone -92.0, D, L-rhamnose +8.9, L-sorbose -43.4, Lactose +55.3, maltose +136.0, sucrose +66.5, ralttinose +105.2, trehalose +178.3.