Question

What is the molality of the solution, if 2.82 g of glucose dissolved in 30 g of water?

Answer 1

Explanation:

you should ask molality , not molarity because for finding molarity we have require volume of solution , this is possible when you will give either volume of solution or density of solution .

(a) 2.82g of glucose are dissolved in 30g of water

∴ mass of solute = 2.82 g , mass of solvent = 30g

Now, molality = mass of solute × 1000/{mass of solvent (in g) × molar mass of solute }

= 2.82 × 1000/(30 × 180)

= 2820/5400

= 0.5222 m

Hence, molality = 0.5222m

(b) mole of glucose = 2.82/180 = 0.0156

mole of water = 30/18 = 5/3 = 1.66

total number of mole = 0.0156 + 1.66 = 1.6756

∴ mole fraction of glucose = mole of glucose/total number of mole

= 0.0156/1.6756

= 0.00931

Also mole fraction of water = mole of water/total number of mole

= 1.66/1.6756

= 0.990