A solution of ethanol (C2H5OH) in water is prepared by dissolving 67.1 mL of ethanol (density = 0.79 g/cm3) in enough water to make 250.0 mL of solution. What is the molarity of the ethanol in this solution? solve it out too please
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Mass of ethanol used = 67.1 mL x 0.79 g/mL = 53.009 g.
Molar mass of ethanol = 46.07 g mol−1 therefore moles of ethanol used = 53.009 g/46.07 g mol-1
= 1.1506 mol.
This number of moles is contained in 250 mL of solution but molarity is moles per litre or 1000 mL.
If 1.1506 moles are contained in 250 mL, 1 mL of this solution contains (1.1506 / 250) moles and 1000 mL contains (1000 x 1.1506 / 250) moles = 4.60 moles.
Molarity of the ethanol is therefore 4.60 mol/L or 4.60 M.
Molar mass of ethanol = 46.07 g mol−1 therefore moles of ethanol used = 53.009 g/46.07 g mol-1
= 1.1506 mol.
This number of moles is contained in 250 mL of solution but molarity is moles per litre or 1000 mL.
If 1.1506 moles are contained in 250 mL, 1 mL of this solution contains (1.1506 / 250) moles and 1000 mL contains (1000 x 1.1506 / 250) moles = 4.60 moles.
Molarity of the ethanol is therefore 4.60 mol/L or 4.60 M.