Choosing which pipet to use

The Mohr pipet measures volumes by taking the initail volume reading minus the final volume reading, so the Mohr pipet will is used when the volume of a transferred liquid must be known, but the quantity of that liquid does not need to be an exact number.

Unlike the Mohr pipet, the volumetric pipet does not measure volumes by difference. The volumetric pipet has a single graduation to indicate volume, and the pipet is drained completely when the liquid is transferred. Hence, the volumetric pipet is used when a given volume must be delivered exactly.