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Chemical reactions & Solutions & ACIDS BASES. Adding H + or OH -. HCl + H2O H3O + + Cl - + H2O NaOH + H2O Na + + OH - + H20 Our model considers these reactions as couples that attend where one party is disinterested (Young woman and brother) (Young man and aunt).
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Adding H+ or OH- HCl + H2O H3O+ + Cl- + H2O NaOH + H2O Na+ + OH- + H20 Our model considers these reactions as couples that attend where one party is disinterested (Young woman and brother) (Young man and aunt) GSCI 163 Spring 2010
The process of forming couples must depend on the number of single men and single women in an area. Consider: • Equal numbers • Lots of men few women • Lots of women few men It is plausible that the rate of forming couples depends on the product. rate = [M][W] This at least has the correct behavior. • Lowering either number increase rate • Increasing either increases the rate • Lowering one can be compensated by increasing the other. Might feel confident that the meeting probability has to depend on this product. GSCI 163 Spring 2010
Therefore at some point the room stabilizes with a certain number of couples separating and equal number forming. The number of single men and women is then fixed. GSCI 163 Spring 2010
Strong and Weak Adding some molecules to water the entire solution consists of ions so that the number of additional H+ or OH- is easy to find. The maximum number of H+ or OH- are added. These molecules are referred to as strong acids or bases. If only a fraction of the molecules are present as ions the number of additional H+ or OH- will depend on this fraction. The compounds are typically referred to as weak acids or bases. GSCI 163 Spring 2010
HCL @ PH = 1Need PH = 5 [H+]=0.1 moles/liter [H+]=0.00001 moles/liter Need to dilute by 10,000 Original 1 liter beaker has to be added to 10,000 liters. GSCI 163 Spring 2010
HCL @ PH = 1Need PH = 5 Add NaOH HCl(aq) + NaOH (aq) H2O +NaCl H+ in on liter = 0.10000 moles Remove = 0.09999 H+ remaining = 0.00001 NaOH has MW=23+16+1=40 g/mole (Need about 4 grams) GSCI 163 Spring 2010
Buffer A buffer solution is an aqueous solution consisting of a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid. It has the property that the pH of the solution changes very little when a small amount of strong acid or is added to it. Mixing a weak acid and a salt to add the conjugate base. HX + NaX (H+ + X-) + Na + X- + HX + NaX (AQ) The action of a buffer is to neutralize the addition of H+ or OH- and maintain the PH GSCI 163 Spring 2010
Material Water and the H+ or OH- ions. Concentrations and equilibrium PH and logarithms PH for strong acids and bases Neutralizing acids or bases GSCI 163 Spring 2010