Chemistry question involving molality and molarity.?

Question

Water at 25 celcius has a density of 0.997 g/cm3. Calculate the molality and molarity of pure water at this temperature.

Is it just me or am I lacking bits of information to solve for the molality and molarity! help!!

Answer 1

Molarity of Water :
Molecular Wt of water =18;
Density of water at 25 C =0.997 g/cc
Wt. of 1000 cc of water =997 gms

Hence Molarity = 997/18 =55.39 M;

Molality of Water :
Here we have to see the Gm moles in 1000gms of solvent ;

Hence Molality =1000/18 =55.55 M

Answer 2

Molarity is no of moles of solute in one liter of complete SOLUTION; molality is no of moles of solute in one kilogram of SOLVENT. In this case there is no distinction between solution and solvent.

One mole of water is 18 g. One liter of water at the density given is 997g. 997g is 997/18 moles or 55.4 moles. Therefore there are 55.4 moles in the liter of solution, and the molarity is 55.4 (mole/L)

In 1kg of water there are 1000/18 = 55.6 moles of water. Therefore the molality is 55.6 (mole/kg)

NOTE: the density was given in three significant figures; the answers should not have more than three sig figs.

Answer 3

you have 3 formulas to play with
Molarity = # moles/Vol
Density = mass/volume
Relative Mol mass = # moles/mass

If you play around with them you get
Molarity = Relative Mol mass * density = 18 * .997 = 17M

Do the same where Molality = # moles/mass

Answer 4

Molarity is moles in a given answer. In each and each answer you indexed, there is one mole in line with liter. so which you have the comparable moles in line with quantity of answer. The molarity of the two recommendations are the comparable.