105.987. First we have to find the atomic mass of each atom of the molecule Na = 22.98977, C = 12.011 and O = 15.999. Since we have two atoms of Na the atomic mass of Na need be multiplied by 2, in case of carbon is 1 and 3 for oxigen and add them all together. 2x(22.98977) +1x(12.011) + 3x(15.999) = 105.987