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
To find the molarity of KBr in the final solution, we first need to determine the moles of KBr in each initial solution. The formula to calculate moles of a solute is:
Moles = Molarity × Volume (in liters)
For the 25.0 mL sample of 1.00 M KBr:
Moles of KBr = 1.00 M × 0.025 L = 0.025 moles
For the 75.0 mL sample of 0.800 M KBr:
Moles of KBr = 0.800 M × 0.075 L = 0.060 moles
Now, we can calculate the total moles of KBr in the initial solution by summing the moles from both samples:
Total moles of KBr = 0.025 moles + 0.060 moles = 0.085 moles
The next step is to calculate the new molarity after evaporation. Since there is a change in volume, the moles of KBr will remain constant, but the volume will change. To find the new molarity, we divide the total moles of KBr by the final volume, which is 50.0 mL (convert to liters):
Molarity = Moles / Volume (in liters) = 0.085 moles / 0.050 L = 1.70 M
The molarity of KBr in the final solution is then 1.70 M.
To find the molarity of KBr in the final solution, we need to calculate the moles of KBr in each original solution and the final volume of the solution.
First, let's calculate the moles of KBr in the 25.0 mL sample of 1.00 M KBr:
Moles = Molarity × Volume
Moles = 1.00 mol/L × 0.025 L
Moles = 0.025 mol
Next, let's calculate the moles of KBr in the 75.0 mL sample of 0.800 M KBr:
Moles = Molarity × Volume
Moles = 0.800 mol/L × 0.075 L
Moles = 0.060 mol
Now, let's add the moles of KBr from both original solutions to find the total moles of KBr:
Total moles = 0.025 mol + 0.060 mol
Total moles = 0.085 mol
Next, let's calculate the final volume of the solution by evaporating water:
Final volume = 50.0 mL
Finally, we can calculate the molarity of KBr in the final solution:
Molarity = Moles / Volume
Molarity = 0.085 mol / 0.050 L
Molarity = 1.70 mol/L
Therefore, the molarity of KBr in the final solution is 1.70 mol/L.