A student tests for a specific heat of copper using cups and a thermometer. Why would this measurement be different than the accepted specific heat of copper?

Answer 1

The accepted specific heat that we know would be measured in a bomb calorimeter, which is a closed system. We know this means the net heat inside cannot change, it will just transfer to what is inside the calorimeter. Whenever you use an open system, you will loose heat, as it is not contained in the system. It is this loss of heat that causes the percent error in your experiment.