Question

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Today is my chemistry exam...
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Answer 1

1.......
Mass percent = mass of solute / mass of solution .

Where mass of solution = mass of solute +  mass of solvent

Here mass of solution = 500g

Mass percent = 2.5 % 

Let the mass of solute be x.

Then 2.5 %  = x / 500

⇒ x = 12.5g

Hence mass of sugar is 12.5 g

∴ mass of solvent = mass of solution - mass of solute

∴ mass of solvent = 500 g - 12.5g

⇒ mass of solvent = 487.5 g 

Hence 487.5 g of water is required to prepare 500g of 2.5 % sugar solution. 



2....
Weight of solute = 2.5g
Weight of solvent = 50g

Molality = (Weight of solute / Weight of Solvent) * 1000
= (2.5/50) * 1000
= 50 m

Concentration of solution is 50 m

Answer 2

Calculate rhe concentration of a solution which contains 2.5 g of salt dissolved in 50g of water