# A stock solution of 10M NaOH is prepared. From this solution, you need to make 250mL of 0.375M solution. How many mL will be required?The answer if 9.4mL but I don't know how to get that.

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### 2 Answers

suppose, V ml is the volume required from the stock solution,

and then the number of moles in that V will be, n1

n1 = 10 mol/dm3 x (v/1000)

n1 = v/100

This amount of moles are in 250mL of 0.375M solution,

therefore,

0.375 = (v/100)/250 x 1000

0.375 = v/25

v = 9.375 mL

But the amount you can measure by a measuring cylinder (10 mL) is 9.4 mL. (0.1 mL accuracy)

Therefore the answer is 9.4 mL

There are two kinds of solutions:the one we have(10 M),and the one we need(0.375M).What is the same in these solutions? the amount of substance of solute.

Assuming that xL is required.

10x=0.375*0.25

the answer is 0.009375L=9.375mL.

And you need a graduated container, such as a cylinder

It can contain 10mL.

but the smallest scale is 0.1mL.

9.375mL in it and you can only read 9.4 ml.

it is the container that makes difference.