Answer:
1) the product may be contaminated by the solvent
2) side reactions may yield unwanted products
3) some reactants may be present in the product if the reaction was incomplete
Step-by-step explanation:
It is common in chemistry to pass reaction products through purification processes. This is done for a number of reasons.
First of all, some solvents molecules may be attached to the reaction product. These solvent particles must be separated in order to obtain a pure product.
Secondly, some side reactions also yield products that are isolated along with the desired products and these must be separated accordingly.
Finally, some chemical reactions do not go on to completion. This implies that some reactants may still be isolated alongside the product at the end of the reaction.