Q calculate the molarity of a solution of ethnol in water in which the mole fraction of ethnol is 0.040 ?
Asked by hardik | 11th May, 2012, 05:35: PM
Expert Answer:
Mole fraction = 0.04/1 = 1/25.
In 25 moles of the total mixture, 1 mole of ethanol and 24 moles of water are present. 24 moles of water weigh 24 x 18 = 432 g = 432 mL (18g is the molar mass of water)
1 mole of ethanol is present in 432 mL of water. Molarity is no. of moles of solute present in 1 L of solution.
So molarity = 1 x 1000 / 432 = 1000/432 = 2.315 M (approx.)
Mole fraction = 0.04/1 = 1/25.
In 25 moles of the total mixture, 1 mole of ethanol and 24 moles of water are present. 24 moles of water weigh 24 x 18 = 432 g = 432 mL (18g is the molar mass of water)
1 mole of ethanol is present in 432 mL of water. Molarity is no. of moles of solute present in 1 L of solution.
So molarity = 1 x 1000 / 432 = 1000/432 = 2.315 M (approx.)
Answered by | 11th May, 2012, 05:42: PM
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