The gain in mass by the negative electrode is the same as the loss in mass by the positive electrode. So the copper deposited on the negative electrode must be the same copper ions that are lost from the positive electrode.
Kinetic energy is the energy possessed by a body while in motion. Potential energy on the other hand is the energy possessed by a body based on its position.
Kinetic energy of a body is determined by the equation; K.E = 3RT/2;
From the equation, kinetic energy is directly proportional to the temperature of the system and therefore an increase in the kinetic energy of a sample causes an increase in temperature of the system.