Homework #6 1995 Answer #2

Time (hr)

Cp (mg/L)

0.125

14.00

0.25

11.50

0.5

8.42

0.75

6.81

1

5.95

1.5

5.19

2

4.88

3

4.53

4

4.23

6

3.71

9

3.05

12

2.50

18

1.68

24

1.13

Plot the Data on Semi-log Graph Paper

The green line and symbols represent the Cplate line. A value for can be calculated from this line to be 0.0662 hr-1 with the intercept value, B = 5.53 mg/L. The table below can be completed with the calculation of the residual (= Cp - Cplate). Plotting the Residual versus time gives the red line on the graph above. From this line it is possible to calculate = 2.74 hr-1 (from the slope) and A = 12.0 mg/L (from the intercept)

Time (hr)

Cp (mg/L)

Cplate (mg/L)

Time (hr)

Residual (mg/L)

0.125

14

5.49

0.125

8.51

0.25

11.5

5.44

0.25

6.06

0.5

8.42

5.35

0.5

3.07

0.75

6.81

5.27

0.75

1.54

1

5.95

5.18

1

0.77

1.5

5.19

5.01



2

4.88

4.85



3

4.53

4.54



4

4.23




6

3.71




9

3.05




12

2.5




18

1.68




24

1.13




The results so far:
Parameter Value Units
2.74 hr-1
0.0662 hr-1
A 12.0 mg/L
B 5.53 mg/L

= 0.910 hr-1

= 0.200 hr-1

= 1.70 hr-1

= 17.1 L

= 51.5 L