Lab final questions

Question 1

When is it ok to work alone in the lab?

Answer 1

NEVER!!!

Question 2

Why isn’t it advisable to wear contacts in the lab?

Answer 2

Gas could become trapped underneath them, they could react with a chemical vapor, and lenses can fall out of your eyes.

Question 3

Can you heat closed containers?

Answer 3

Nope

Question 4

Where can you find C=C bond on IR? What else is found there? Which has the largest spike?

Answer 4

You can find them from 1600-1850. It is accompanied by C=N and C=O. C=O has the largest spike, followed by C=N

Question 5

Where is C-+= found? What else is found with it?

Answer 5

2100-2300 with C triple bond N

Question 6

Where is H-x found?

Answer 6

2700-4000

Question 7

Where is C-H found?

Answer 7

2700-3200

Question 8

Where is N-H and O-H found? What is peculiar about O-H?

Answer 8

3200+, OH is super broad.

Question 9

;What is found at 2750-2850?

Answer 9

Double point with a bridge for H-C=O

Question 10

Some clean up ranges. C-Br, C-Cl, C-N, C-O

Answer 10

C-Br: 500-600
C-Cl: 600-800
C-O: 1000-1100
C-N:1000-1200

Question 11

What is the range of the phenol ring?

Answer 11

1450-1600 or 1650-2000

Question 12

What does integration mean?

Answer 12

The number of signals that corresponds with number of protons in the identical environment.

Question 13

What does splitting means?

Answer 13

Splitting indicates the number of neighbors that a given hydrogen has, indicated by N+1.

Question 14

What is chemical shift?

Answer 14

Either up or downfield depending on the carbons proximity to an electronegative atom.

Question 15

When doing an acid bas extraction, what is the general principal?

Answer 15

We are trying to separate the acidic part by first neutralizing it to separate it, then making it acidic again, and purifying by crystallization. The reaming aqueous component must be washed, then separated again, then combined with a either, combined with the organic phase and evaporated.

Question 16

Why would we prefer multiple extractions over a single extraction?

Answer 16

It’s more effective in removing the majority of the solute that single extraction with an equal total amount of solvent.

Question 17

What compounds are acidic and which are basic?

Answer 17

The acidic compounds feature a hydrogen with a neutral charge, while the basic compounds feature a negative charge and no hydrogen.

Question 18

Which is the organic layer?

Answer 18

The layer on top or floating.

Question 19

What’s the formula for percent recovery?

Answer 19

Recovered amount/initial amount *100

Question 20

What’s melting point?

Answer 20

It is the point at which a solid material will slowly become a liquid.

Question 21

What does purity have to do with the melting point range?

Answer 21

The less pure a substance, the wider melting point that the substance will have. This is due to the fact that the impurities in the substance will feature different melting points, either higher or lower, causing the melting point range to change.

Question 22

What is the refractive index and what does it tell us?

Answer 22

It looks at how much the light is bent as it passes though a solution. The higher the value, the more concentrated a substance is.

Question 23

What is the relationship between boiling point and retention time?

Answer 23

The more volatile a compound is, the lower boiling point and shorter retention time.

Question 24

how to find product ratios using peaks?

Answer 24

There will be 2 peak areas. Divide one by another to get a product ratio.

Question 25

What is the formula for calculating the percent conversion for the H NMR?

Answer 25

Make sure that your hydrogens are even by dividing the larger by 2 or whatever. Then it is the one your divided (D) / (D+A) *100

Question 26

What is the ideal solvent for recrystalization?

Answer 26

Compound should be soluble in it as a hot solvent and insoluble as possible in cold temps. Should also be inexpensive, unreactive, low toxicity, and low Bolling point.

Question 27

What's the basic process of recrystalization?

Answer 27

Add your two reactants and heat to a boil. Place it in a ice bath with sulphuric acid and wait. Separate via separatory funnel. Take your product and boil in water, let cool and recrystallize.

Question 28

What is the order or reactivity for SN1 and SN2

Answer 28

Sn1: 3 prime, 2 prime, 1 prime, methyl Sn2: Methyl, Primary, Secondary, Tertiary.

Question 29

What is the effect a leaving group identity has on substrate structure on rate of sn1 and sn2

Answer 29

The better a leaving group, the faster that an sn1 reaction will occur, same for sn2. Substate structure, will also affect rate.

Question 30

What's the difference between fractional and simple distillation

Answer 30

Fractional distillation takes longer then simple distillation but does so because it has twice the condensing length. It also creates a more concentrated distillate.

Question 31

Which is more selective between E1 and E2 reactions

Answer 31

The more selective is E2 because the hydrogen leaving group must be anti coplanar to the leaving group, making it so that only some products can be formed.

Question 32

What does bromination prefer, less mor more subsitutued?

Answer 32

Bromination is much more selective, so the more substituted carbon.