A student measured the optical rotation of his sample at two different concentrations. At 0.14 g/mL, he measured áD at –12°. At 0.07 g/mL, he measured áD = +174°. What would the measurement be at 0.28 g/mL?

Answer 1

For 0.07 g/mL the reading is + 174.
For 0.14 (twice that) the reading would be 174+174 = 348 so the reading will be 360-348=-12 (which is listed in the problem). Therefore, the next higher concn of 2x will be -12*2 = -24 OR
348+348=696 and
696-360=336 and 336 is -24 from 360.
Check my thinking.