chemistry
posted by Anonymous on .
A 25.0 mL sample of 1.00 M KBr and a 75.0 mL sample of 0.800 M KBr are mixed. The solution is then heated to evaporate water until the total volume is 50.0 mL. What is the molarity of the KBr in the final soltion?

Use the Molarity Formula
Molarity= moles/liters of solution
Molarity= moles/0.050 Liters
To find moles you have to find the moles of each sample of KBr. SO 1.00M KBR times .025liters =.025moles
And then 0.800M KBR times .075liters=.060moles.
Then you add the moles of both samples and get .085 moles.
SO you plug it into the equation:
Molarity= 0.085moles/0.050liters
Molarity=1.7mol/L