This is part of a longer problem, and probably obvious, but if I calculate this wrong, the rest of the calculations will be wrong too!... Question: Given the mass density, molar mass, and electrical resistivity of a substance at room temperature, how do you calculate the concentration of the conduction electrons assuming the effective mass is equal to the free electron mass??? (Perhaps the electrical resistivity is not necessary to answer this part of the problem?) The rest of the problem asks for mean relaxation time, fermi energy, fermi velocity, and mean free path at the fermi level. I know how to solve for these once I can calculate the concentration of conduction electrons, so I am not completely helpless, but I just can't get the problem started. Thank you!