Question

A salt solution is prepared by dissolving 60g of salt in 140g of water calculate the amount of solute that should be added to this solution in order to make its concentration 50%(w/w)

Answer 1

Answer:

The initial mass of the salt, Msolute = 60 g

The initial mass of water, Msolvent = 140 g

∴ Mass of solution, Msolution = Msolute + Msolvent = 60 + 140 = 200 g

Percentage concentration by mass, %w/w  

= [Msolute / Msolution] * 100

= [60 / 200] * 100

= 30 %

Now, by using the unitary method we can write

When % concentration by mass is 30%, then Msolute = 60 g

∴ When % concentration by mass is 50%,  then Msolute = [60/30]*50= 100 g

Thus, in order to make its concentration 50%, 100 g of salt should be present in the solution.

We already have 60 g of salt so we require, 100 – 60 = 40 g more amount of salt to be added in the solution.

Answer 2

Explanation:

this is the correct answer

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