Question

If i have 340mL of a 1.5 M NaBr solution, What will the concentration be for 1000mL?

Answer 1

Answer:

0.51M

Explanation:

Given parameters:

Initial volume of NaBr = 340mL

Initial molarity  = 1.5M

Final volume  = 1000mL

Unknown:

Final molarity = ?

Solution;

This is a dilution problem whereas the concentration of a compound changes from one to another.

In this kind of problem, we must establish that the number of moles still remains the same.

    number of moles initially before diluting = number of moles after dilution

Number of moles  = Molarity x volume

Let us find the number of moles;

          Number of moles  = initial volume x initial molarity

Convert mL to dm³;

                  1000mL  = 1dm³

                     340mL gives $\frac{340}{1000}$   = 0.34dm³

Number of moles  = initial volume x initial molarity  = 0.34 x 1.5 = 0.51moles

Now to find the new molarity/concentration;

               Final molarity  = $\frac{number of moles}{Volume}$    = $\frac{0.51}{1}$    = 0.51M

We can see a massive drop in molarity this is due to dilution of the initial concentration.