Question

You have a solution containing 135.2 g of dissolved kbr in 2.3 l of water. what volume of this solution, in ml, would you use to make 1.5 l of a 0.10m kbr solution

Answer 1

The concentration of KBr in the solution can be calculated by dividing mass by dissolved volume.
Mass dissolved - 135.2 g 
Volume - 2300 mL
Concentration - 135.2 g/ 2300 mL = 0.059 g/mL
For the solution to be prepared, required molarity - 0.10 M KBr
The volume to be prepared - 1.5 L
amount of moles required to make this solution - 0.10 mol/L x 1.5 L = 0.15 mol
The mass of KBr required - 0.15 mol x 119 g/mol = 17.85 g

From the solution already made we have to make the new solution.
The concentration of solution - 0.059 g/mL
If mass of 0.059 g contained in - 1 mL
Then volume containing 17.85 g  - 1/0.059  x 17.85 = 302.54 mL
Volume required - 302.5 mL