1. The problem statement, all variables and given/known data How many moles of electrons weigh 1 kg? 2. Relevant equations 3. The attempt at a solution We know the mass of an electron= 9.1*10-31kg. So no of electrons in one Kg will be 1/9.1*10-31. Then we just divide that by 6* 1023 to get the number of moles. But my teacher told me that i need to first convert the mass into grams for the calculations. Does it matter in this case since we're dealing with electrons?