(a) The 1H NMR spectrum of DMF exhibits three signals. Upon treatment with excess LAH followed by water, DMF is converted into a
new compound that exhibits only one signal in its 1H NMR spectrum. Explain. DMF, like most , exhibits restricted rotation about the bond between the carbonyl group and the nitrogen atom. This restricted rotation causes the groups to be in different electronic environments. They are not chemically equivalent, and will therefore produce different signals (in addition to the signal from the other proton in the compound). Upon treatment with excess LAH followed by water, DMF is to an amine that exhibit restricted rotation. As such, the methyl groups chemically equivalent and will together produce . (b) Based on your answer to part a, how many signals do you expect in the 13C NMR spectrum of DMF? Restricted rotation causes the methyl groups to be in electronic environments. As a result, the 13C NMR spectrum of DMF should have .
1 answer:
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Explanation:
According to the Henderson-Hasselbalch equation, the relation between pH and is as follows.
pH =
where, pH = 7.4 and = 7.21
As here, we can use the nearest to the desired pH.
So, 7.4 = 7.21 +
0.19 =
= 1.55
1 mM phosphate buffer means +
= 1 mM
Therefore, the two equations will be as follows.
= 1.55 ............. (1)
+
= 1 mM ........... (2)
Now, putting the value of from equation (1) into equation (2) as follows.
1.55 = 1 mM
2.55 = 1 mM
= 0.392 mM
Putting the value of in equation (1) we get the following.
0.392 mM + = 1 mM
= (1 - 0.392) mM
= 0.608 mM
Thus, we can conclude that concentration of the acid must be 0.608 mM.
Answer:
His results will be skewed because there was more water than stock solution. Which would cause the percentage solution to be less than 50% therefore the density would be less than the actual value.
Explanation:
The solution will have percentage less than that of 50%. Therefore the density would be less than the actual value.
Suppose there should be 50 mL of the solution, and he added 60 mL. So 10 mL of the solution is added more.
Suppose the mass of the solute is m.
Originally, the density is =
Now after adding extra 10 mL , the density becomes .
Therefore,
So the density decreases when we add more solution.
I hope this helps :)
