I’m trying to solve a question about a saturated salt solution but am unsure of how to answer one of the parts or what it’s asking for.
The maximum solubility of table salt (NaCl) in water at 25 degrees Celsius is approximately 359 g/L. Assume the volume of the solution does not change with the addition of salt.
a) What is the molar concentration of the mixture in mol/L?
b) What is the molal concentration of the mixture in mol/kg? Assume that the density of water is 980 kg/m3.
c) How many moles of Cl2 gas would need to be present in order to make up an equivalent amount of saturated salt solution?
d) What is the density of the mixture?
a) molar concentration
359 g NaCl * 1 mol NaCl / 58.44 g NaCl = 6.14 mol => 6.14 mol/L
b) molal concentration
(1 L H2O * 1 m3 H2O * 980 kg) / (1000 L H2O * 1 m3) = 6.14 mol / 0.980 kg = 6.26 mol/kg
c) moles of Cl2 gas
I thought it was asking how many moles of chlorine gas is equivalent to the amount of salt in the 1 L solution (359 g NaCl). There are 70.9 g in 1 mole of Cl2, so that gives me an answer of 5.06 mol Cl2 gas (359 g NaCl / 70.9 g Cl2).
But the answer key states the correct solution as 3.07 mol Cl2 gas. How should I go about this part?
d) density of the mixture
density of water = 980 kg/m3
density of salt = 359 g/L => 359 kg/m3
density of mixture = (980 + 359) kg/m3 = 1339 kg/m3