List two possible steps where impurities may be gained, which would appear to be an increase in copper yield (why you may get more than 100% of the copper back at the end). Be specific about the steps and

how they might add impurities.

i) During washing

ii) During Measurement

Explanation:

The two possible steps are :

i) During washing : during the washing method the residue may be not completely dried out and this residue ( water) will add up to the final product ( copper yield ) and this kind of error is called human error.

ii) During measurement : If the weighing instrument is faulty there might be addition  in value of the final copper yield which will see the final yield value > 100% . this error occurs when the initial value and final value is  been weighed