posted by Lou .
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 = ?