An aqueous solution of NaCl has a concentration of .500 M. 35.0 mL of this solution is allowed to evaporate to a volume of 20.0 mL.

a) Is the solution more concentrated or more dilute afterwards?
b) What is the new concentration of the solution?

M = mols/L

a. If some solvent (L) has evaporated then L is a smaller number and M goes up and it is more concentrated.

b. new concn =
I would use 0.500M x (35/20) = ? BUT YOU may prefer to use the dilution formula.
c1v1 = c2v2
c = concentration
v = volume
35 mL x 0.500 = 20 mL x ?M
?M = 35*0.500/20 = ?

To determine whether the solution is more concentrated or more dilute afterwards, we need to compare the initial concentration with the final concentration after evaporation.

a) Comparing the initial volume (35.0 mL) with the final volume (20.0 mL), we can see that less solvent is present after evaporation. As a result, the solution is more concentrated afterwards.

b) To find the new concentration, we can use the formula:

C1V1 = C2V2

Where:
C1 = Initial concentration
V1 = Initial volume
C2 = New concentration
V2 = New volume

Given:
C1 = 0.500 M (initial concentration)
V1 = 35.0 mL (initial volume)
V2 = 20.0 mL (new volume)

Now, substitute the values into the formula and solve for C2:

0.500 M x 35.0 mL = C2 x 20.0 mL

17.5 = 20C2

Divide both sides by 20.0:

C2 = 17.5 / 20.0

C2 = 0.875 M

Therefore, the new concentration of the solution after evaporation is 0.875 M.

To determine whether the solution is more concentrated or more dilute after evaporation, we need to compare the initial concentration before evaporation with the final concentration after evaporation.

a) To determine if the solution is more concentrated or more dilute afterwards, we need to compare the initial and final volumes of the solution.

Initial volume of the solution = 35.0 mL
Final volume of the solution = 20.0 mL

Since the final volume is smaller than the initial volume, this means that the solution has become more concentrated after evaporation.

b) To find the new concentration of the solution after evaporation, we can use the relationship between initial and final volumes and concentrations.

Initial concentration of the solution = 0.500 M
Initial volume of the solution = 35.0 mL
Final volume of the solution = 20.0 mL

First, we can use the formula C1V1 = C2V2, where C1 is the initial concentration, V1 is the initial volume, C2 is the final concentration, and V2 is the final volume.

Substituting the given values, we get: 0.500 M * 35.0 mL = C2 * 20.0 mL

Next, solve for C2 (the final concentration):

C2 = (0.500 M * 35.0 mL) / 20.0 mL

C2 = (17.5 mol/L * mL) / 20.0 mL

C2 = 0.875 M

Therefore, the new concentration of the solution after evaporation is 0.875 M.