Question

To prepare 0.5M KCl solution from 100 ml of 0.40 M KCI
which of the following should be done?
(1) add 0.745 g KCI (2) add 20 ml of water
(3) add 0.1 mole KCI (4) evaporate 10 ml of water
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Answer 1

Hey Friend,

Here is your Answer,

4) evaporate 10 ml of water.

Because if you add water then concentration of this solution are got less and in given question we need to make higher concentration. When you evaporate water Concentration of kcl's concentration are more then before.

Thank Uh...

Answer 2

Answer:

0.745 g of kcl is to be added

Explanation:

Original solution contains

As we know

No of moles=molarity*volume

No of moles =0.5*100/1000

=0.05 mole

Initial soln

No of moles=0.40*100=0.04

In order to balance we need

0.05-0.04=0.01 mole

Now

Molae mass * moles =mass

76 approx*0.01=0.76 gram

U can do it directly think intuitively

If we add water the concentration ie molarity will obviously decrease

Now u can have a gist between 1st and 3rd