2007 ADA questions/help with answers please

This forum made possible through the generous support of SDN members, donors, and sponsors. Thank you.

Member 8586

Full Member
10+ Year Member
Joined
Dec 14, 2011
Messages
496
Reaction score
1
ah so i did the sciences of the ADA 07 yesterday and i was kinda of surprised bc the way people talk about it on here...maybe i expected it to be a SUPER breeze idk :-/ ...it WAS easier than others BUT some of the bio questions and chem questions were a little weird, with the wording and types of calculations so they took longer than anticipated...the orgo was def really easy though but i still got two wrong :/

bio 35/40
#12 - all biosynthetic reactions in living cells lead to a MORE ordered state and DECREASE in entropy? why did i think it was INCREASE in entropy ..bc we use and release energy?
#36 - the rate and type of cleavage occuring after fertilization would be most affected by the amount and distribution of yolk? i had no idea this and never heard of it...did i miss something somewhere?

GC 27/30

#51 - During a titration it was determined that 30mL of a 0.1M Ce4+ solution was required to react completely with 20.0mL of a 0.150M Fe2+ solution. Which one of the following reactions occurred?
WTH - i have no idea what to even do with this, especially with the answer choices given...i read someone elses response to this question but still nothing
#60- stupid mistake by overthinking it...i ended up setting up the chart, doubling the concentration of B and seeing how that effected rate and put that itd be 1/4 of the original ...
i was indeed wrong in doing this right?
ie i had concentration of B in the chart as ...1 and 2...so rate would be 4 (2^x = 4) according to the original, which would make x = 2....so then in the chart i doubled B to 4, so 4^x = 4 which would make x = 1

OC 28/30

#73 - Ethane reacts with chlorine in the presence of heat or UV light to give chloroethane. CH3CH3 + Cl2 -->heat or UV--> CH3CH2Cl + HCl
why is the intermediate with a radical instead of carbocation?

Members don't see this ad.
 
for the gen chem #51...if they both come together to react to completion then look at it this way

moles Ce4+: 0.1M=x moles/0.03L=0.003 moles Ce4+ needed

moles Fe2+: 0.15M=x moles/0.02=0.003 moles Fe2+ needed

since they use they equal the same number of moles, the mole fraction is 1:1 and answer C is the only one that has a 1 to 1 ratio in the reactants

For the orgo question...whenever you see any reaction in the presence of UV light then u automatically thing radical and not carbocation
 
for the gen chem #51...if they both come together to react to completion then look at it this way

moles Ce4+: 0.1M=x moles/0.03L=0.003 moles Ce4+ needed

moles Fe2+: 0.15M=x moles/0.02=0.003 moles Fe2+ needed

since they use they equal the same number of moles, the mole fraction is 1:1 and answer C is the only one that has a 1 to 1 ratio in the reactants

For the orgo question...whenever you see any reaction in the presence of UV light then u automatically thing radical and not carbocation

at the chem question..thanks..wow i had no idea how to even go about that..i even thought of calculating the moles but the answer choices made NO sense to me ...how likely am i to even see anything like this? ive never seen this before

orgo question - awesome thanks thats what i figured but wasnt sure..mad i got that simple problem wrong
 
haha no problem...as far as how likely you are to see the question, I cant really answer that but it isnt that hard of a question the wording is just confusing. Honestly with the DAT, like 99% of the questions given are actually very simple but they word them in a way that is meant to throw you off so you have to use ur knowledge and apply it to what they are really asking.

As for the orgo one...I really have no explanation to that lol the only reason i know that is cuz of chad so if you want a better explanation then check out video 3.3 free radical halogenation. UV light=radical formation
 
Top