Answer: The concentration of lead nitrate Pb(NO3)2 in a 0.726 M solution is 0.755 molal.
Explanation:
Given:
The molar mass of Pb(NO3)2 is 331.2 g/mol
Assuming 1 litre of solution. This would equal 1202 g of solution
In the one litre of solution, you have 0.726 mol Pb(NO3)2
0.726 mol (331.2 g/mol) = 240.5 g Pb(NO3)2
Mass of water in 1 L of solution = 1202 g - 240.5 g = 961.5 g = 0.9615 kg
Molality = mols of solute / kg of solvent
= 0.726 mol / 0.9615 kg
= 0.755 m Pb(NO3)2
