Highest boiling point……..?
septembre 8th, 2008 by maryharmonFirst, you have to figure out the number of moles of each compound by dividing the mass (10 g) by the molar mass (figured out by adding the atomic mass of each atom).
(10 g of C6H12O6) / (180 g per mole) = 0.056 moles
(10 g of CaCl2) / (110 g per mole) = 0.091 moles
(10 g of NaBr) / (102.9 g per mole) = 0.097 moles
(10 g of C12H22O11) / (342 g per mole) = 0.029 moles
And you know that ionic compounds dissociate.
So 0.091 moles of CaCl2 dissociate into 0.091 moles of Ca2+ and 2*0.091 moles of Cl-. So the total number of moles of that compound is 0.091 + 2*0.091 = 0.273 –> 0.27 moles (rounded off according to the rules of significant figures).
Similarly, 0.097 moles of NaBr dissociate into 0.097 moles of Na+ and 0.097 moles of Br- which brings it to a total of 0.194 –> 0.19 moles.
C6H12O6 and C12H22O11 do NOT dissociate because they are organic molecules. (Organic molecules are nonpolar molecules that contain carbon atoms.)
The more moles of a substance, the more number of “obstacles” there are so it requires a higher temperature to boil. Thus, 10 g of CaCl2 (0.27 moles of atoms) will result in a solution with the highest boiling point.