Question

A chemist needs to make 250 mL of a 2.50 M aqueous solution of ammonium hydroxide from a 6.00 M ammonium hydroxide solution. How much water must be combined with a sample of the 6.00 M solution to make the diluted solution? The answer is 146 mL but I keep getting 104 mL through M1V1=M2V2. What must I additionally do?

Answer 1

Answer:

250 mL (total solution)  = 104 mL (stock solution)  + 146 mL (water)

Explanation:

Data Given

M1 = 6.00 M

M2 = 2.5 M

V1 = 250 mL

V2 = ?

Solution:

As the chemist needs to prepare 250 mL of solution from 6.00 M ammonium hydroxide solution to prepare a 2.50 M aqueous solution of ammonium hydroxide.

Now

first he have to determine the amount of ammonium hydroxide solution that will be taken from6.00 M ammonium hydroxide solution

For this Purpose we use the following formula

                    M1V1=M2V2

Put values from given data in the formula

                   6 x V1 = 2.5 x 250

Rearrange the equation

                   V1 = 2.5 x 250 /6

                    V1 = 104 mL

So 104 mL is the volume of the solution which we have to take from the 6.00 M ammonium hydroxide solution to prepare 2.5 M  aqueous solution of ammonium hydroxide

But we have to prepare 250 mL of the solution.

so the chemist will take 104 mL from 6.00 M ammonium hydroxide solution and have to add 146 mL water to make 250 mL of new solution.

in this question you have to tell about the amount of water that is 146 mL

250 mL (total solution)  = 104 mL (stock solution)  + 146 mL (water)