200309M1 - Chem237 rl4idterm I from Fall 2OO3 Which...

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2. Chem 237 rl4idterm I from Fall 2OO3' l"/ Which statement(s) is(are)Jfalse about H-bonds? Indicate all that apply. ,.d H-bonds are involved in tertiary structure of proteins. ,H H-bonds are important in the structure of water (v the side chain of valine can H-bond with that of serine. A hydrogen bonding occurs in ice crystals. Sl^ H-bogds are not very strong, about 4 kcal/mol, so H-bonds are not a very important factor in the stability ol proteln structure. Given the following compounds, which is a good choice for a butler at pH 6.8? g. MES pKu : 6. I @ phosphoric acid pK^: 7.2 c. HEPES pKu 7.5 d. Tris base pKu 8.3 e. Not enough information-the volume of the buffer is also needed. /-14"t 4 Suppose you have two solutions:(l) 0.1 M acetic acid and (2) 0.1 M potassium acetate. You mix these solutions as follows: ,,. . .. t (solution A) 50 mL of each I and2 (solution B) 25 mL of I and 75 mL of 2 I q:.'; -, (solution CS lSmLof I and25 mLof2 - e1'.F* i-'i What are the relative pH values of the three solutions, A]frn'd CT* \ a:B:c }' a<B<c 3. t/ y -c. B<A<C t-A td}lc<A<B '
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