BIO 202 Lecture 3

BIO 202 Lecture 3 - pH Buffers Macromolecules 1 Lipids...

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pH, Buffers, Macromolecules 1: Lipids, Carbohydrates
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Solutions • Solutions of molecules are characterized by their concentration – Most commonly used concentration is molarity Molarity (M) = number of moles per liter of solution Mole = amount of substance equal to its molecular weight in grams. The amount of grams in 1 mole of substance depends on its chemical formula, but 1 mole of any substance will contain the same number of molecules [1 gram- mole ~6.022 x 10 23 molecules (Avogadro number)] Molecular weight = sum of weights of all the atoms in the molecule • Example - NaCl: Na = 23, Cl = 35.5, MW= 58.5 2 M solution of NaCl contain 2 x 58.5 = 117 g of NaCl in a total volume of 1 liter (to make: dissolve 117 g NaCl in H 2 O, then add H 2 O to total of 1 liter)
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Dissociation of water • Water itself can dissociate. An electron gets attracted to O, and leaves H altogether: • Normally, only 1 molecule of H 2 O in 554 x 10 6 molecules is dissociated • The concentration of H + (protons) is 10 -7 M at 25°C • The concentration of OH - (hydroxyls) is also 10 -7 M at 25°C H 2 O H + + OH -
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How can we change concentrations of H + or OH - ? • Dissolve in water a substance that will
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BIO 202 Lecture 3 - pH Buffers Macromolecules 1 Lipids...

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