A 36.0mL sample of 1.20 M KBr and a 56.0mL sample of 0.700 M KBr are mixed. The solution is then heated to evaporate water until the total volume is 60.0mL. What is the molarity of the KBr in the final solution?
moles soln 1 = M x L = ?
moles soln 2 = M x L = ?
final molarity = total moles/total L. total L will be 60.0 mL = 0.060L.
1.37M
To find the molarity of KBr in the final solution, we need to calculate the amount of KBr molecules present after the solution is mixed and the water is evaporated.
First, let's determine the moles of KBr in each initial solution:
For the 36.0 mL of 1.20 M KBr:
moles = volume (in L) x molarity
moles = 0.036 L x 1.20 mol/L
moles = 0.0432 mol
For the 56.0 mL of 0.700 M KBr:
moles = volume (in L) x molarity
moles = 0.056 L x 0.700 mol/L
moles = 0.0392 mol
Next, we need to find the total moles of KBr by summing the moles from both initial solutions:
total moles = moles from the first solution + moles from the second solution
total moles = 0.0432 mol + 0.0392 mol
total moles = 0.0824 mol
Since the total volume of the final solution is 60.0 mL, we need to convert it to liters:
volume (in L) = 60.0 mL ÷ 1000
volume (in L) = 0.060 L
Finally, we can calculate the molarity of KBr in the final solution:
molarity = total moles ÷ volume (in L)
molarity = 0.0824 mol ÷ 0.060 L
molarity ≈ 1.37 M
Therefore, the molarity of KBr in the final solution is approximately 1.37 M.