midterm wint02

midterm wint02 - Seat # _ Last initial _ Chemistry and...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Seat # ________ Last initial ________ Chemistry and Biochemistry 153A Winter 2002 Midterm Examination Question # Value Score 1 23 2 23 3 20 4 10 5 11 6 25 7 10 8 30 TOTAL 152 __________ KEY _______________ Print your full name ( last name first) ______________________________ Student ID Number ______________________________ Print your TA's name ______________________________ Discussion section # [or time & day] I have read the instructions below. ______________________________ Signature INSTRUCTIONS READ EACH QUESTION CAREFULLY! SHOW YOUR CALCULATIONS! WRITE YOUR LAST NAME IN THE SPACE PROVIDED ON EVERY PAGE OF THE EXAM. NO CREDIT WILL BE GIVEN FOR ANYTHING WRITTEN ON THE BACK OF A PAGE OR ANYWHERE OTHER THAN THE SPACE PROVIDED FOR EACH ANSWER. ANSWERS MUST BE BRIEF AND TO THE POINT. WHERE A WORD LIMIT IS SPECIFIED, NO CREDIT WILL BE GIVEN FOR THE PART OF THE ANSWER IN EXCESS OF THE LIMIT. Numbers in parentheses represent the point values.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Name ______ KEY __________________ 2 1. (23) a. (3) Circle an expression that represents an acid/base reaction that could cause a resistance to change in pH upon addition of hydroxide to a dilute aqueous solution containing a weak acid, HA. H 2 O H + OH - H + + H 2 O + H 2 O H 3 O + OH - - HA H 2 O A - H 2 O + HA H 3 A +±±± - H 3 O + H 2 A + b. (6) Fill in the blanks giving the concentrations of each of the following species in a dilute aqueous solution at pH 8. [H 2 O] = __ 55.5 _____ M [H + ] = __ 10 -8 ___ M [OH-] = ____ 10 -6 ____ M c. (6) - equiv. 1 pH 0.5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 a b c d 1) The above plot shows the titration of 2mmoles of a weak acid, HA, in dilute aqueous solution. Write a balanced equation showing the predominating reaction occurring between points "a" and "b" on the plot as OH - is added. H 2 O H + OH - +H 3 O + OH - or 2H 2 O 2) What is the pK a for deprotonation of the weak acid, HA, represented in the above plot? __ 6 _______ 3) What is the ratio A - over HA at point c on the plot? _ 1000/1 or _ 10 -3 ___ 4) What is the pH of the solution represented by the plot when 1.5 mmoles of OH - have been added? __ 7 _ d. (8) Name the four classes of biological macromolecules. ___________ proteins _____________________ ____________ polysaccharides ____________ ___________ lipids _______________________ ____________ nucleic acids _______________ These four classes of macromolecules play a large number of biological roles in living organisms. This suggests a high level of structural diversity leading to great complexity in the structures of these macromolecules. What two major factors permit the necessary structural diversity while maintaining a degree of simplicity in structure? 1) __ Macromolecules are polymers of known simple subunits ___________________________________ _____________________________________________________________________________________________ 2) ___ Many _macromolecules are virtually ubiquitous (i.e., similar or identical macromolecules in many different and diverse organisms ____________________________________________________
Background image of page 2
Name ______ KEY __________________ 3 2. (23 ) a.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 7

midterm wint02 - Seat # _ Last initial _ Chemistry and...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online