it doesn't matter if yield is in moles or grams because moles = grams / Mr , and Mr is same top and bottom because it's the same compound, Mr cancels to give grams anyway.
Do you remember the exact question for mass spec? Was that the question where it was multiple compounds with the same molecular formula, or just same Mr? I do remember it saying "to the nearest whole number" but H, O, C, N etc, are all .0 on our data sheet, wasn't sure how many d.p in high.res.
It was the one that had the dioic acid in part 1 and the two diol isomers in part 2, or something, and the question asked why/how you could tell the dioic acid apart from the diols using high res mass spec. Them not being specific about the precision means use your imagination! Take the limit as the decimal places goes to infinity, ya feel? You can tell apart anything with a different molecular formula. (I've done a question where some high precision masses were given - it was something along the lines of of 4 d.p.)
The NMR isomer structures I did in the last 5 minutes of the exam, hated them.
Tell me your answers so I can update this I can’t really remember much
Equation 1,6-dibromohexane and excess ammonia
C6H12Br2 2 NH3 —-> C6H16N2 2 HBr or C6H12Br2+ 4NH3 —> 2NH2(Ch2)6NH2 + 2NH4Br (this is probably the correct equation but not sure)
Nucleophilic substitution skeletal formula with ammonia Cyclic compound by-product Cyclic compound was from the amino group nucleophilic.sub. on the bromine on the same molecule? reacts with itself.
Equation of ethanoic anhydride (hydrolysis? can't remember) Forms Ethanoic Acid and Ethanol
Question about a compound and why it has no chiral carbon No chiral centre because no carbon has 4 distinct groups attached
Explain the term Complementary in terms of DNA strands Dna strands have complementary base pairs which are able to form hydrogen bonds between them
Draw hydrogen bonds between the strands 3 bonds between C and G 2 bonds between A and T
Circle the components that make up the nucleotide with cytosine 3 Circles around: Phosphate group, 2-Deoxyribose, Cytosine
Vegetable Fat Question with CxHy
Initial Rates 3.2 x 10^-4 3.2 x 10^-4 First order Second order
Bunch of numbers I can remember 1.39 182kg 20000 2.57 x 10^9 Arrhenius 28.5% percentage yield units mol-3 dm9 s-1
Diagram Distillation apparatus Add condenser and thermometer
Hydrolysing proteins HCl or NaOH debate about his one
Labelling infrared spectrum F,G,E can’t remember the order Ester at top (bc no OH peak), then alcohol, then, carboxylic acid.
6 marker on the 2 different compounds (one was a cyclic ketone the other was an alcohol) -boiling points Hydrogen bonding in one of them stronger than dipole forces -Cnmr -infrared spec
CO2 how does it cause global warming C=O absorbs IR (heat radiation). Absorbs this energy / retains heat / increases temp of gas (guessing for the second mark).
Minimum number of amino acids in mixture 7
How to see the amino acids Fluorescent dye and UV/Ninhydrin
How can they tell if the sample has dried by adding anhydrous calcium something ... Drying cyclohexane makes the solution turn clear ?
The weird question on Z,Z adding the carbons to a skeletal formula Z,Z, skeletal formula has double bond between 9/10 and 12/23. Z same side, so chain curls
Name mechanism with benzene Electrophilic substitution
Reaction with bromine finish off the mechanism - electrophilic addition forming carbo cation then the second bromine ion adds on. Forms dibromo...
Distinguishing between primary and tertiary alcohol Add acidified potassium dichromate Orange --> Green No Change
Last question about nucleophile not being able to attack an Alkene. I think it’s either: C=O is polar so the nucleophile can attack the partially positive carbon. The alkene doesn’t have a C=O group so not polar so can’t be attacked by nucleophile. OR The nucleophile repels the double bond in the alkene
Insufficient NaH4B added. Test for aldehyde Add tollens/fehlings Silver mirror/red ppt
Molecular/Emperical formula question C5H8 you had to times by 5 to get a whole number Structure was a branched monomer, e.g H2C=C(CH3)--CH=CH2
Formula of the dicarboxylic acid with an Mr of 118 HOOC- (CH2)2 -COOH
Draw two structures for C6H3Br3 One with One peak in C nmr One with 4 peaks in C nmr Benzene ring/kekule structure (several correct answers for this one) D with 4 peaks on 13C spectrum was 1,2,3-tribromobenzene - C2,C3,C4,C5 symmetrical same as C2,C1,C6,C5
Synthesis question Nitrobenzene to amine equation finish off equation Add 6[H] to form 2H2O
Reagents for the reduction of nitrobenzene Reagents are H2 and Ni (more than one correct answer for this one)
Reagents and conditions for 2 step synthesis to form an amine KCN aqueous ethanolic Sn/HCl (think there is more than one correct answer for this one)
Why does stereoisomerism occur Restricted rotation around C=C bond. Higher priority groups on same or opposite sides of the double bond.
Draw isomers for golf ball Don't degrade because no polar bonds, so not susceptible to nucleophillc attack.
Isomer of C4H8Br2 with 2 singlet peaks on 1H spectrum Structure was C(CH2Br)(Br)(CH3)2
How does high-res mass spec differentiate molecules with Mr = 118? - electro spray adds H increasing mass. Higher precision will distinguish between them because they're the same to the nearest whole number
Why would it be better to use anhydrides rather than acyl chlorides? Don't use acyl chlorides because toxic HCl fumes/ reacts violently - irritant / acid raid.
It was the one that had the dioic acid in part 1 and the two diol isomers in part 2, or something, and the question asked why/how you could tell the dioic acid apart from the diols using high res mass spec. Them not being specific about the precision means use your imagination! Take the limit as the decimal places goes to infinity, ya feel? You can tell apart anything with a different molecular formula. (I've done a question where some high precision masses were given - it was something along the lines of of 4 d.p.)
The NMR isomer structures I did in the last 5 minutes of the exam, hated them.