Question
Mole fraction of C2H5OH in aqueous solution is 0.25. If the density of solution is 0.967g/ml. calculate molarity and molality.
0.75 mole water contains ...................................... 0.25 mole C2H5OH
so 0.75*18 gm contains ....................................... 0.25 mole
now calculate moles of alcohol in 1000 gm water. It will be molality
similarly
0.75 mole water contains ...................................... 0.25 mole C2H5OH
so 0.75*18 gm contains ....................................... 0.25*46 gm
so 0.75*18+0.25*46 gm solution contains ........................... 0.25 mole alcohol
so (0.75*18+0.25*46)*0.967 ml solution contains ............................. 0.25 mole alcohol
now calculate moles of alcohol in 1000 ml solution. It will be molarity
Read 2 Solution.
o.25=n/n+55.5 find n ie moles of c2h5oh and then find molality & molarity
denstiy se vol find and moles se find mass of c2h5oh and now put in formula 4 molality and molarity