an aqueous solution containing only NaOH is simultaneously 10.71 molal and 9.96 M in the solute. calculate the density in g/cm^3. the answer is 1.328 but how did they get it?
thanks for any insight
2007-11-23 13:49:32 · 2 answers · asked by Levi M 1 in Science & Mathematics ➔ Chemistry
The reason for this problem is that when NaOH or other chemicals dissolve in water, the volume of the solution does not equal the volume of the solvent and solute.
Back to the question at hand, one liter of solution contains 9.96 moles/L x 40 g/g-mole or 384 grams/Liter. Molality is in terms of moles per kg SOLVENT. So 10.7 molal means that 428 grams of NaOH mixes with 1 kg of water. Comparing these, 428/384 is the volume of a 10.7 molal solution, or about 1.11 Liter. So if you divide 1428 g (428 from NaOH and 1000 from water) by 1.11 Liter,you should get the density quoted.
2007-11-23 14:23:55 · answer #1 · answered by cattbarf 7 · 1⤊ 0⤋
molarity =no of moles /vol of answer......(a million) molality=no of moles/wt of solvent........(2) divide (2) by potential of (a million) molality/molarity=wt of solvent/vol. of answer=density of sol subsequently density is 0.795 Kg/L
2016-12-16 17:09:06 · answer #2 · answered by ? 4 · 0⤊ 0⤋