Molarity Questions: Calculate Resulting Solutions

[Kdawg]

What is the molarity of each resulting solution when the following mixtures are prepared?

553.6 mL H2O is added to 20.0 mL 4.79 M HNO3

20.8 mL 1.75 M HCl is added to 80.0 mL 0.534 M HCl

 

[FZ+]

Come on! This isn't very hard if you give a moment's thought...

1 M = 1 mol per dm^3

1 dm^3 = 1000 ml

Calculate the number of moles in each case, making the appropiate conversions, and divide by the total volume of solvent.

 

[ravenprp]

To calculate the molarity of a solution, we use the formula M = moles of solute / volume of solution in liters. In the first mixture, we are adding 553.6 mL of water to 20.0 mL of 4.79 M HNO3. First, we need to convert the volume of water to liters by dividing by 1000: 553.6 mL / 1000 = 0.5536 L. Next, we need to calculate the moles of HNO3 in the solution before the water is added. This can be done by multiplying the volume (in liters) by the molarity: 20.0 mL / 1000 = 0.02 L * 4.79 mol/L = 0.0958 moles HNO3. Now, we can calculate the molarity of the resulting solution by dividing the moles of HNO3 by the total volume of the solution: 0.0958 moles / (0.5536 L + 0.02 L) = 0.168 M HNO3. This means that the molarity of the resulting solution is 0.168 M HNO3.

In the second mixture, we are adding 20.8 mL of 1.75 M HCl to 80.0 mL of 0.534 M HCl. We can follow the same steps as before to calculate the molarity of the resulting solution. First, we need to convert the volume of the added HCl to liters: 20.8 mL / 1000 = 0.0208 L. Then, we calculate the moles of HCl in the added solution: 0.0208 L * 1.75 mol/L = 0.0364 moles. Next, we calculate the moles of HCl in the original solution: 80.0 mL / 1000 = 0.08 L * 0.534 mol/L = 0.0427 moles. Finally, we can calculate the molarity of the resulting solution by dividing the total moles of HCl by the total volume of the solution: (0.0364 moles + 0.0427 moles) / (0.0208 L + 0.08 L) = 0.079 M HCl. Therefore, the molarity of the resulting solution is 0.079