 # Question : Concentration of 1 molar solution is     a) more than 1 molal solution     b) less than 1 molal solution

10 years ago
concentration of 1 molar solution is higher than 1 molal solution.......since density of water=1 then 1 mole of solute is present is 1000 ml of water (1000ml=amount of (solute +solvent)) so mass of solvent would be less than 1000 g so 1 molar solution is more concentrated
10 years ago

As per my understanding, whether one will be greater than the other will depend upon the density of the solvent.

Take for example- We take a solute like NaCl (which actually doesnt contribute to the volume of the solution after getting dissolved because it goes into the intermolecular spaces of the solvent) and water.

Water has a density of 1kg/L.

Therefore, if we are adding x moles of NaCl in 1L of  water, then,

Molarity= x Molar

Molality= x Molal (Since, 1L of water has a mass of 1kg)

Therefore, in this case, Molarity=Molality

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Now , consider the same x mloes of NaCl being mixed into 1L of any other solvent of density p kg/L such that p>1.

Then,

Molality= x Molar

Molality= x/p Molal (and you can see that x/p < x)

Therefore, in this case, Molality < Molarity.

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Finally, consider x moles of NaCl being mixed into 1L of any solvent of density q kg/L such that q<1.

Then,

Molarity= x Molar

Molality= x/q Molal ( and you can see that x/q > x)

Therefore, in this case, Molality > Molarity.