posted by jessica .
describe how you would prepare 500 mL 0.250 M ethylene glycol (MW=62.07) from concentrated 31% (w/w) solution that has a density of 1.0350 g/mL
31% w/w means 31.0 g ethylene glycol in 100 g solution.
mols ethylene glycol = grams/molar mass = about about 0.5 but you may need to do it more accurately.
Use density to convert 100 g soln to volume. volume = mass/density = 100/1.0350 = about 95 mL.
Then M = mols/L soln. Substitute and solve for M of the 31% material.
Then use the dilution formula of
c1v1 = c2v2 where\
c = concn
v = volume
and dilute the 31% material.