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Date: 25-2-2018
1452
Date: 2-3-2018
1446
Date: 26-4-2017
1970
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Interconversion of Composition Measures
Given the solution composition in mass percent, it is easy to compute the mole fractions of solute and solvent and the molal concentration of solute.
Example 1
What are the mole fractions and molal concentrations in a 10% by weight solution of CH3OH in water? We first compute the number of moles of CH3OH and water:
The total number of moles is 5.33 and the mole fractions are:
The molal concentrations of CH3OH is computed from the number of moles and the mass of H2O.
Molar concentrations involve the volume of the solution and to get this from the mass, we need the density.
Example 2
Given that the density of 10.0% aqueous NaCl is 1.071 g/cm3, what is the molar concentrations of Na+ and Cl-?
Two approaches are possible. (1) We know how many moles of NaCl are contained in 100 g of solution. Thus we have
(2) One liter of solution weighs 1071 g and contains 107.1 g NaCl/L; converting to moles, we have [NaCl] = [Na+] = [Cl-] = 1.83 mol/
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علامات بسيطة في جسدك قد تنذر بمرض "قاتل"
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أول صور ثلاثية الأبعاد للغدة الزعترية البشرية
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مكتبة أمّ البنين النسويّة تصدر العدد 212 من مجلّة رياض الزهراء (عليها السلام)
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