An unknown compound was determined to be 74.97% carbon, 8.39% hydrogen, and no nitrogen. Calculate the empirical formula.
answer
Carbon : 74.97g x 1mol/12g = 6.2475mol of C
Hydrogen: 8.39g x 1mol/1g = 8.39mol of H
100 - (74.97+8.39) = 16.64
Oxygen: 16.64 x 1mol/16g = 1.04mol of O
6.2475/1.04 = 6.007
8.39/1.04 = 8.067
1.04/1.04 = 1
Formula = C6H8O
question
Can IR spectroscopy be used to distinguish 2-pentanone from 2-hexanone? Why or why not
answer
No
IR distinguishes molecules based on functional groups. 2-pentanone and 2-hexanone both have a carbonyl group. NMR would be a better method.
question
Explain the purpose of the hot gravity filtration. Why is it good to use the stemless funnel for this technique?
answer
The purpose of hot gravity filtration is to remove any insoluble impurities from your sample.
It is better to use a stemless funnel because a funnel with a stem is prone to premature recrystallization.
question
The density of acetic anhydride is 1.08g/ml. How many moles of acetic anhydride are used in this experiment.
answer
Given: 1.8ml used in experiment
MW: 102.09g
Density: 1.08g
1.8ml x 1.08g/1ml x 1mol/102.09g = 0.019mol
question
Calculate the amounts of p-acetamidophenol (in grams) and bromoethane (in milliliters) that are used in this reaction.
Given: 10mmol of p-acetamidophenol
15mmol of bromothane
answer
*p-acetamidophenol
10mmol x 1mol/1000mmol x 151.17g/1mol = 1.5117g
*Bromothane
15mmol x 1mol/1000mmol x 108.97g/1mol x 1ml/1.46g = 1.11955ml
question
What is ligroin? Is it polar or nonpolar?
answer
Ligroin is a petroleum derivative, it is a volatile hydrocarbon mixture and is nonpolar.
question
What is a simple experiment that you could use to determine if the two samples made though the two synthetic routes are identical.
answer
A mixed melting point to see is samples are the same.
-->Mix two samples from both parts and see if m.p. is the same as theoretical.
question
Why is HCL used instead of just plain deionized water, in the acid base rxn of p-phenetidine and hcl.
answer
The hydrochloric acid was used to more readily protonate the amine when compared to water. Increasing the solubility of the amine so it can be easier to use in the synthesis.
question
Which of the following are immiscible/miscible.
If they are immiscible which one will on top?
1.Hexane and Water
2.Methylene choride and Water
3.Ethanol and Water
4.Ether and Water
answer
1. immiscible, Hexane on top
2.immiscible, Water on top
3. miscible
4.immiscible, ether on top
question
Explain why phenol is much more acidic than cyclohexanol?
answer
The conjugate base of cyclohexanol has no resonance structures and therefore less stable then phenol who is resonance stabilized by the benzene ring.
question
Could you separate 2,4-dinirtophenol from benzoic acid using the extraction methods in out experiment?
answer
No, since the pkas are so close, you cannot selectively deprotonate one acid without deprotonating the other.
