An aqueous solution contains 4.9 % NaCl by mass. You may want to reference ( pages...

An aqueous solution contains 4.9 % NaCl by mass. You may want to reference ( pages 586 - 592) Section 13.5 while completing this problem. 1.Calculate the molality of the solution. Express the molality to two significant figures. Part B Calculate the mole fraction of the solution. Express the mole fraction to two significant figures.

Solutions

Expert Solution

part A

4.9 % NaCl by mass , 4.9 g of NaCl present in 100 g solution.

no of mole of NaCl present in soltion(n) = w/mwt = 4.9/58.5 = 0.084 mol

mass of solvent (w) = 100-4.9 = 95.1 g

molality(m) = n*1000/W

= 0.084*1000/95.1

= 0.88 m

part B

no of mole of NaCl present in soltion(n) = w/mwt = 4.9/58.5 = 0.084 mol

no of mole of water in solution = 95.1/18 = 5.283 mol

molefraction of NaCl = nNaCl/nTotal

= 0.084/(0.084+5.283) = 0.016

molefraction of water = nwater/nTotal

= 5.283/(0.084+5.283) = 0.984

queen_honey_blossom answered 1 year ago

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