Atomic masses are: C 12.01, H 1.01 Present your answer as a numerical value only
ID: 526496 • Letter: A
Question
Atomic masses are: C 12.01, H 1.01Present your answer as a numerical value only, to 2 significant figures in the form x.xEx.If the mole fraction of a solution of octane (C8H18) in benzene (C6H6) is 0.27, what is the molality of octane in the solution? Atomic masses are: C 12.01, H 1.01
Present your answer as a numerical value only, to 2 significant figures in the form x.xEx.If the mole fraction of a solution of octane (C8H18) in benzene (C6H6) is 0.27, what is the molality of octane in the solution?
Explanation / Answer
It is given that mole fraction of octane in benzene is 0.27 - which means that for every (1-0.27) mole of benzene, there are 0.27 moles of octane.
Molality= No.of moles of solute (here octane) / 1 kg of solvent(here benzene)
molar weight of benzene = 78.11 g/mol
No. of moles of benzene to make up a mass of 1 kg= 1000g/(78.11* 0.73)g/mol = 1000/57.02 =17.53 moles
No. of moles of octane for 12.80 moles of benzene = 0.27 * 17.53 =4.73 moles
Therefore, molality of octane in solution = 4.73
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