Posted by Dora on Thursday, April 3, 2008 at 4:53pm.
Use density to determine mass toluene, then convert mass to mols toluene.
Use density to determine mass 150.0 mL benzene,
Then molality toluene = #mols/kg solvent.
molarity = mols/L solution.
Post your work if you get stuck.
i still got it wrong
0.867 g/mol= x/ 20 ml x= 17.94 g
0.874 g/mol= x/ 150 mil x= 131.1 g
toluene 17.904 g x 1 m/ 92.14 g/ mol= .194 m
benzee 131.1 g x 1m/78.1121 g/mol = 1.68 m
.194 m Toluene/ .1311 kg = 1.48
0.867 g/mol= x/ 20 ml x= 17.94 gYou made a math error here. I get 17.34 g
0.874 g/mol= x/ 150 mil x= 131.1 gThis is OK.
toluene 17.904 g x 1 m/ 92.14 g/ mol= .194 m This should be 17.34 g toluene. And that divided by 92.14 = 0.188 mols toluene. Then 0.188/kg solvent = 0.188/0.1311 = 1.434 which I would round to 1.43 for molality toluene.
benzee 131.1 g x 1m/78.1121 g/mol = 1.68 m
.194 m Toluene/ .1311 kg = 1.48 see above for correction.
For molarity of toluene, we have 0.188 mols/150 mL or 0.188/0.150 L = 1.25 mols/L = 1.25 M.