The specific optical rotations of pure a- and -D-mannopyranose are +29.3 and -17.0, respectively. When either form

The specific optical rotations of pure a- and ß-D-mannopyranose are +29.3° and -17.0°, respectively. When either form is dissolved in water, mutarotation occurs, and the observed rotation of the solution changes until a final rotation of +14.2° is observed. Assuming that only a- and ß -pyranose forms are present, calculate the percent of each isomer at equilibrium.