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Ch06Extras

# Ch06Extras - 2 0.18 m Cl-Thus the total concentration of...

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Molarity & molality… CaCl 2 has a molecular weight of 110 g/mol. In the lab, you weigh out 10 grams of CaCl 2 and add water up to 1 L total volume. What is the molarity of your solution? Molarity = moles solute (CaCl 2 ) / liter soln, so: [(1mol CaCl 2 )/(110 g CaCl 2 )] x 10 g CaCl 2 = 0.09 mol CaCl 2 0.09 mol CaCl 2 / 1 L solution = 0.09 M CaCl 2 soln Suppose that instead you’d created your solution by adding 10 g CaCl 2 to 1 L of water. What is the molality of your solution? Molality = moles solute (CaCl 2 ) / kg solvent (water), so: [(1mol CaCl 2 )/(110 g CaCl 2 )] x 10 g CaCl 2 = 0.09 mol CaCl 2 0.09 mol CaCl 2 / 1 kg water = 0.09 m CaCl 2 soln

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Osmolality… What is the osmolality of that second solution? Osmolality = sum of all solute molalities (the identities or chemical natures of the solutes is immaterial) CaCl 2 completely dissociates (ionizes) in water: CaCl 2 -----> Ca 2+ + 2Cl - 0.09 m CaCl 2 ----->

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Unformatted text preview: 2+ + 0.18 m Cl-Thus, the total concentration of this aqueous CaCl 2 solution is 3 x 0.09, or 0.27 Osm (osmolality) Calculating E K … Given these typical concentration gradients, what is the Nernst equilibrium potential for potassium? Wells/VPHY3100/Fall08 Predicting ionic movements The membrane potential (V m ) The Nernst potential (E x ) The charge of ion x So… given the opportunity, in which direction would net movement of a particular ion (x) occur? We can predict this by knowing three things: Wells/VPHY3100/Fall08 Predicting ionic movements The membrane potential (V m ) The Nernst potential (E Mg ) The charge of Mg So… if the membrane were made suddenly permeable to Mg 2+ ions, in which direction would net Mg 2+ movement occur? We can predict this by knowing three things:...
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Ch06Extras - 2 0.18 m Cl-Thus the total concentration of...

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