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Date: 17-4-2017
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Date: 7-5-2017
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Date: 3-5-2017
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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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تفوقت في الاختبار على الجميع.. فاكهة "خارقة" في عالم التغذية
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أمين عام أوبك: النفط الخام والغاز الطبيعي "هبة من الله"
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قسم شؤون المعارف ينظم دورة عن آليات عمل الفهارس الفنية للموسوعات والكتب لملاكاته
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