1) Consider a solution that contains 72.0% R isomer and 28.0% S isomer. If the observed specific rotation of the mixture is -41.0°, what is the specific rotation of the pure R isomer?
2) If a pure R isomer has a specific rotation of -147.0°, and a sample contains 85.0% of the R isomer and 15.0% of its enantiomer, what is the observed specific rotation of the mixture?
3) An aqueous solution containing 4.33 g of an optically pure compound was diluted to 400.0 mL with water and placed in a polarimeter tube 20.0 cm long. The measured rotation was -2.19° at 25 °C. Calculate the specific rotation of the compound.