Things to remeber for exams - specific cases

Question 1

Why does the base-mediated esterification of carbox. acids NOT work

Answer 1

• the carboxylic acid is simply deprotonated and is then left, it is more stable as that anion

Question 2

what is a nice thing to include when thinking about the relative energies of AB and B MOs and stabilities wrt dissociation

Answer 2

draw the energy - bond length diagram
the LJ potential thing and draw the overall lines to show whether there is a minimum at a finite bond length or as bond length tends to infinity

Question 3

what should we do and NOT do when asked to plot a graph using eq. const. k to find deltarH” and deltarS” for a reaction

Answer 3

• DON’T go directly from
  deltarG” = -RTln(K), this requires making certain assumptions
• use the van’t hoff eq. of
  dln(k)/dt = deltarH” / RT^2

so ln(k) on Y against 1/T gives grad -deltarH”/R

• to find deltarS” find deltarG” at a certain temp using -RTln(k) and use deltarH” at the same temp

Question 4

what should we watch for when doing conc’s or rate equations

Answer 4

UNITS
especially when it’s wanted in moelcules s^-1 or similar