Final answer:
It is false that washing crystals with a large portion of solvent during suction filtration is more effective; smaller portions of fresh solvent are typically better for removing impurities efficiently.
Step-by-step explanation:
The statement that it is more effective to wash the crystals with a large portion of solvent is false. It is typically better to wash crystals with two or three small portions of solvent rather than one large volume during suction filtration. This is because smaller portions of fresh solvent can more effectively remove impurities without dissolving too much of the desired compound.
The solvent can carry away the impurities while minimising the dissolution of the purified product, making the overall purification process more efficient. In the context of fractional crystallization, impurities must be more soluble than the compound of interest.