Molarity = number of moles of solute / liters of solution number of moles = molarity * liters of solution number of moles of Na2C2O4 = 0.1 * 0.25 = 0.025 moles
Now, from the periodic table: mass of Na = 22.9 grams mass of C = 12 grams mass of O = 16 grams molar mass of Na2C2O4 = 2(22.9) + 2(12) + 4(16) = 133.8 grams Therefore, one mole is equal to 133.8 grams. To know the mass of 0.025 moles, all you have to do is cross multiplication as follows: mass = (0.025*133.8) / 1 = 3.345 grams
In covalent bonding, the octet rule is important because sharing electrons gives both atoms a full valence shell. As a result, each atom can consider the shared electrons to be part of its own valence shell.