25 ml of a concentrated solution of sodium chloride is added to a 500 ml volumetric flask and sufficient water added to make up to the mark. the concentration of this diluted solution is 0.125 m. what was the concentration of the original solution?

2.5 M

Explanation:

To address this question, we can use the dilution formula:  

M1V1= M2V2

Where M1 is the concentration of the concentrated solution  

V1 is the volume of the concentrated solution (the amount of mL that we                            take from the initial solution)  

        M2 is the concentration of the diluted solution  

V2 is the volume of the diluted solution or the final volume.  

For this case, we know V1, M2 and V2 and we want to know M1.  

Following the formula, M1=  

Therefore, M1 =  

For this, the  concentration of the original solution is 2.5 M.

I hope this clarifies your inquiry.