the copper anode is weighed before and after the electrolysis reation. if the copper anode is not completely dry when it is weighed after the electrolysis how would this affect the value of the faraday's constant calculated?

Faraday's constant will be smaller than it is supposed to be.

Explanation:

If the copper anode was not completely dry when its mass was measured, mass of the copper must be heavier than it should have been. Hence, the calculated Faraday's constant would be smaller than it is supposed to be since when calculating Faraday's Constant, the charge transferred is divided by the moles of electrons.