Optical isomerism in tartaric acid.
- (+)-Tartaric Acid. It rotates the plane of polarised light to the right (anticlockwise direction) and is called dextrorotatory.
- (-)- Tartaric Acid. It rotates the plane of polarised light to the (anticlockwise direction) and is called laevorotatory. (-)Tartaric acid is the mirror image of (+)-tartaric acid and vice verse.
- Meso-Tartaric Acid. It possesses a plane of symmetry and is consequently optically inactive. This optically inactive form is said to be internally compensated (Optical rotation of one asymmetric carbon is cancelled by that of the other).
- (±)-Tartaric Acid. It does not rotate the plane of polarised light. That is, it is optically inactive. It is an equimolar mixture of (+)-and(-)-forms (racemic mixture).