in the final reaction of the copper cycle, which experimental error would not decrease the overall percent recovery of copper? there was excess granular zinc, but hcl was added until all the zinc had reacted. some solution was spilled before the zinc was added for the reaction. some solid was left in the beaker after transferring the precipitate to the evaporating dish. not enough hcl was added to react with the excess granular zinc, so some zinc was included with the copper in the evaporating dish.