A solution of Al2 (SO4) 3 {d=1.253gm/ml } contain 22% salt by weight. The molarity, normality, and molality of the solution is?

2 Answers

22% by mass means 22 g solute/100 g solution.

How many mols in 22g? That’s 22/342 about 0.064 mols which is an estimate as are all of the other calculations that follow. You should recalculate each for yourself.

So we have 0.064g solute/100 g solution. Use the density to convert 100 g to volume. mass = v x d or v = m/d = 100/1.253 = about 80 mL or 0.08 L

Then M = mols/L = about 0.064/0.08 = about 0.8M

How many mols in 22g? That’s 22/342 about 0.064 mols which is an estimate as are all of the other calculations that follow. You should recalculate each for yourself.

So we have 0.064g solute/100 g solution. Use the density to convert 100 g to volume. mass = v x d or v = m/d = 100/1.253 = about 80 mL or 0.08 L

Then M = mols/L = about 0.064/0.08 = about 0.8M

N = M x #+/- charges = 0.8M x 6 = ?

m = mols/kgsolvent. We have 0.064 mols/100 g solutions and that is made of 0.064/(22g solute + 78 g solvent) so

m = 0.064/0.078 = ?

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