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
the first is right, the second has no description at all.
To calculate the mass percent of a solution, you need to determine the mass of the solute (in this case, ethanol) and the mass of the solution (in this case, ethanol + water).
For the first question, you correctly identified that the mass of ethanol is 45.6 grams. Now, to find the mass of the solution, you need to add the mass of ethanol and the mass of water.
Given that the mass of water is 245 grams, the total mass of the solution is:
45.6 grams (ethanol) + 245 grams (water) = 290.6 grams
To find the mass percent, divide the mass of the solute by the mass of the solution and then multiply by 100:
(45.6 grams / 290.6 grams) x 100 = 15.7%
Therefore, your answer of 15.7% is correct.
Moving on to the second question, you have a desired solution of 500.0 mL with a concentration of 4.5M of hydrochloric acid (HCl), but you only have 18.0M HCl available for dilution. To create the desired solution, you need to dilute the concentrated solution.
To dilute the HCl, you will use the dilution formula:
M1V1 = M2V2
Where:
M1 = initial concentration (18.0M)
V1 = initial volume (unknown)
M2 = final concentration (4.5M)
V2 = final volume (500.0 mL or 0.5L)
Substituting the known values into the formula, you can solve for V1 (initial volume):
(18.0M)(V1) = (4.5M)(0.5L)
V1 = (4.5M)(0.5L) / 18.0M
V1 = 0.1253L or 125.3 mL
Therefore, your answer of 0.1253L or 125.3 mL is correct.