a) What is the mass in percentage of iodine, I2, in a solution containing 0.035 mol I2
in 115 g of CCl4?
The mass per cent of a component in a solution is given by
Mass % of component = (mass of component / total mass of solution) x 100
so, mass % of I2 = (mass of I2 in solution / total mass of solution) x 100
to find the mass of I2, convert 0.035 mol I2 to grams; the molecular weight of I2 is 253.809 gm/mol
(b) Seawater contains 0.0079 g of Sr2+ per kilogram of water. What is the concentration of Sr2+ in ppm?
from the info in the problem, we have the mass of Sr2+ and the total mass of the solution
(1 kg). We just divide (like in part a) and multiply x 106 to get ppm.