Do my answers look correct for these? Thanks
Calculate the mass percent of a solution containing 45.6 grams ethanol (C2H6O) in 245 grams of water.
15.7%
You are asked to make 500.0 mL of a 4.5M solution of HCl, but the only HCl you have available to dilute is 18.0M. Describe how you would make the desired solution.
.1253L
To calculate the mass percent of a solution, you need to determine the mass of the solute (ethanol in this case) and the total mass of the solution (ethanol + water). Then you can use the formula:
Mass percent = (mass of solute / mass of solution) * 100%
For the first question, you correctly calculated the mass percent as 15.7%. Well done!
Now, for the second question, to calculate the volume of the 18.0M HCl solution you need to use to make the desired 4.5M HCl solution, you can use the formula:
(C1 * V1) = (C2 * V2)
Where C1 is the concentration of the stock solution (18.0M), V1 is the volume of the stock solution you need to calculate, C2 is the concentration of the desired solution (4.5M), and V2 is the final volume of the desired solution (500.0 mL).
Let's plug in the values:
(18.0M * V1) = (4.5M * 500.0 mL)
Now, solve for V1:
V1 = (4.5M * 500.0 mL) / 18.0M
Calculating the expression gives approximately 125.3 mL. So, your answer of 0.1253 L is not correct; it should be 125.3 mL.
Therefore, to make the desired solution, you need to measure 125.3 mL of the 18.0M HCl solution and dilute it to a final volume of 500.0 mL by adding enough solvent (typically water) to reach that volume.