Assignment:
DETERMINING THE RATE CONSTANT FOR MUTAROTATION
Pretend that you are running the following experiment as outlined below.
1. Prepare 100 mL of 5.0% (w/v) D-glucose solution. Fill the polarimeter cell with the solution. The cell is 10 cm in length. The polarimeter is set at 586 nm.
2. Zero the polarimeter on air.
3. Measure the optical rotation every five minutes and record the value.
4. Your data is outlined below:
|
POLARIMETRY DATA
|
|
Time (min)
|
[a] o
|
log [a]
|
2.3 log [a]
|
|
0
|
5.60
|
0.75
|
1.72
|
|
5
|
4.90
|
|
|
|
10
|
4.43
|
|
|
|
15
|
4.05
|
|
|
|
20
|
3.72
|
|
|
|
25
|
3.45
|
|
|
|
30
|
3.25
|
|
|
|
35
|
3.10
|
|
|
|
40
|
3.01
|
|
|
|
50
|
2.80
|
|
|
|
60
|
2.64
|
|
|
|
70
|
2.60
|
|
|
We will assume that this first-order reaction obeys the expression ln [At]/ln [A0]= -kt. Peforming the conversion to log10 and rearranging the log expression yields:
2.3 (log10 [At] - log 10 [A0]= -kt.
We will use the simulated data to calculate the rate constant k.The initial rate is calculated due to the equilibrium being established between the two forms of glucose.
1. Calculate the log10 for each of the optical rotation data points. Record that number in the table.
2. Convert the log10 to ln by multiplying by 2.3. Record that number in the table.
3. Plot the raw data : Time (min) = x, [a] = y on graph paper. Draw a smooth line through the data points.
4. Re-plot the data using Time (min) =x , 2.3 log [a]= y on graph paper.
5. Draw a straight line through the initial data points that appear most linear. This is probably the first three to four points.
6. Calculate the slope (k) of the line. The units are min -1 .
7. How do think the addition of a small amount of acid would affect your reaction rate?
Provide complete and step by step solution for the question and show calculations and use formulas.