Calculate the external pressure that must be applied to seawater, 1.14 m total ion concentration at 10 degrees c if the maximum concentration allowed in the product water is 176 mg/l. assume that all the dissolved salts in the product water is sodium chloride. so, i know that i need to subtract the ion concentrations before using the pi=mrt formula, but i can't figure out how to convert mg/l into molarity. !