Where do electons come from that flow in a circuit of magnesium+copper strip,dialysis tube,sulfate solution?

Question

This was a science experiment. A circuit was made of 2 alligator clips, 1 bulb, 250 mml beaker, funnel, copper sulfate solution, sodium sulfate solution, 50 ml beaker, magnesium strip, copper strip, dialysis tubing, and buzzer

Answer 1

Your description of the setup is not very clear, but the electrons are coming either from the copper, or the magnesium, being oxidized or reduced. For example the oxidation state of copper metal is zero, the oxidation state of copper in copper sulfate is Cu2+. So if the copper metal is being oxidized to Cu2+, that's two electrons per copper atom. Depending on your setup, it may be going the opposite way, in which case the electrons are coming from the magnesium (Mg -> Mg2+)

Answer 2

1