IA data based, boiling point estimation using molecular model vs carbon fraction with molecular weight model.

1. Which model, molecular weight or molecular weight with carbon fraction model, a better
predictor for b/p.
Independent variable
Dependent
variable
Data from CRC. Click here data
IA secondary data based – Regression analysis for boiling point estimation
Boiling point model = 49.5(carbon fractions)0.2791 + (molecular weight)0.5039 - 273
This model is based on density function theory and polarized continuum model
done by researcher. Click here to more info
Research Question
Use 5 - 25 carbon chains for regression model
Use regression eqn to estimate the b/p for carbon length of 10, 26, 30.
Find the % error using expt values with predicted values.
Using molecular weight model 3rd order as predictor for b/p.
Using carbon fractions with molecular weight model as predictor for b/p.
Molecular
formula
Carbon
fraction
Molecular
weight
Boiling point
CH4 0.2 16 -161.5
C2H6 0.25 30 -89.42
C3H8 0.272 44.1 -42
C4H10 0.285 58.12 -1
C5H12 0.294 72.15 36
C6H14 0.3 86.18 69
C7H16 0.304 100.21 98.4
C8H18 0.307 114.23 114.23
C9H20 0.31 128.2 128.2
C10H22 0.3125 142.28 142.28
Data PubChem. Click here Data PubChem. Click here Data PubChem. Click here
Boiling point model = 0.000006x3 – 0.0064x2 + 3.0855x – 153.76
Molecular
formula
Number
carbon
Molecular
weight
Carbon
fraction
Boiling
point
CH4 1 16 0.2 -161.5
CH4 = carbon fraction =
1 𝑐𝑎𝑟𝑏𝑜𝑛
1 𝑐𝑎𝑟𝑏𝑜𝑛+4 ℎ𝑦𝑑𝑟𝑜𝑔𝑒𝑛
=
1
5
= 0.2
Is molecular weight, carbon fraction a good predictor

2. Class Functional group/name Examples
alkene C = C Alkenyl ethene
alkyne C ≡ C Alkynyl ethyne
alcohol OH Hydroxyl ethanol
ether C – O - C Ether methoxymethane
ketone O
‖
C – C - C
Carbonyl propanone
aldehyde CHO Aldehyde ethanal
Carboxylic
acid
COOH Carboxyl ethanoic acid
ester O
‖
C – O -R
Ester ethyl ethanoate
amide O
‖
C – NH2
Amide propanamide
amine NH2 Amine ethanamine
nitrile C ≡ N Nitrile propanenitrile
Class Functional gp Suffix Example Formula
Alkane C - C - ane ethane CnH2n+2
Homologous Series
carbon IUPAC
name
Structure formula Molecular
formula
Boiling
point
1 Methane CH4 CH4 Gas
2 Ethane CH3CH3 C2H6 Gas
3 Propane CH3CH2CH3 C3H8 Gas
4 Butane CH3(CH2)2CH3 C4H10 Gas
5 Pentane CH3(CH2)3CH3 C5H12 Liquid
6 Hexane CH3(CH2)4CH3 C6H14 Liquid
Physical properties
• Increase RMM / molecular size
•RMM increase ↑ - Van Der Waals forces stronger ↑
↓
Melting /boiling point increases ↑
(Increasing polarisability ↑)
London dispersion forces/temporary dipole ↑
1 2 3 4 5 6 7 8 9 10
number carbons – RMM ↑
150
100
50
0
-50
-100
-150
-200
b/p
increase ↑
boiling point
room temp
gas
liquid
Homologous Series
number
Carbons / RMM ↑
1 2 3 4 5 6 7 8 9 10
boiling point
boiling point increase with increase carbon atoms
alcohol
alkane
alkene
alkyne
London dispersion force
(temporary dipole)
H2 bonding
carboxylic acid > alkane/alkene/alkyne
alcohol
carboxylic acid

3. Number
carbon
Molecular
weight b/p
predicted b/p
using model
1
2
3
4
5 72.15 36
6 86.18 69
7 100.21 98.4
8 114.23 125.6
9 128.2 151
10 142.28 174.1
11 156.31 196
12 170.33 216.2
13 184.37 234
14 198.39 253.6
15 212.42 270.6
16 226.41 286.9
17 240.4 302
18 254.5 317
19 268.5 330
20 282.5 343
21 296.6 363
22 310.6 368
23 324.6 379
24 338.6 391
25 352.7 403
IA secondary data based –Regression analysis for boiling point estimation
Research Question
Use 5 - 25 carbon chains for regression model
Use regression eqn to estimate the b/p for carbon length of 10, 26, 30
Find the % error using expt values with predicted values.
Using molecular weight model 3rd order as predictor for b/p.
Using carbon fraction with molecular weight model, as predictor for b/p.
Molecular weight 3rd order as predictor for b/p
Number
carbon
Molecular
weight
Carbon
fraction b/p
predicted b/p
using model
1
2
3
4
5 72.15 0.294 36
6 86.18 0.3 69
7 100.21 0.304 98.4
8 114.23 0.307 125.6
9 128.2 0.31 151
10 142.28 0.3125 174.1
11 156.31 0.314 196
12 170.33 0.315 216.2
13 184.37 0.317 234
14 198.39 0.318 253.6
15 212.42 0.319 270.6
16 226.41 0.32 286.9
17 240.4 0.3207 302
18 254.5 0.3214 317
19 268.5 0.322 330
20 282.5 0.3225 343
21 296.6 0.323 363
22 310.6 0.3235 368
23 324.6 0.3239 379
24 338.6 0.3243 391
25 352.7 0.3246 403
Carbon fraction and molecular weight as predictor for b/p
Independent
variable
Independent variable Dependent
variable
Dependent
variable

4. Predicted b/p for carbon 10 – MW of 142.3
3rd order fit, y = 0.000006x3 – 0.0064x2 + 3.0855x – 153.76
b/p=0.000006(142.3)3 – 0.0064(142.3)2 + 3.0855(142.3) – 153.76 = 173
Research Question
Which model, molecular weight model, 3rd order, better predictor for b/p.
Which model, molecular weight and carbon fraction model, better predictor for b/p.
y = 6E-06x3 - 0.0064x2 + 3.0855x - 153.76
R² = 0.9998
0
50
100
150
200
250
300
350
400
450
0 50 100 150 200 250 300 350 400
b/p
molecular weight
molecular weight vs b/p
Predicted b/p carbon 10 – using model CF – 0.3125, MW – 142.28
y = 49.5(carbon fractions)0.2791 x (molecular weight)0.5039 - 273
b/p=49.5(0.3125)0.2791 x (142.28)0.5039 -273 = 162
Predicted b/p for carbon 26 – MW of 366.7
3rd order fit, y = 0.000006x3 – 0.0064x2 + 3.0855x – 153.76
b/p=0.000006(366.7)3 – 0.0064(366.7)2 + 3.0855(366.7) – 153.76 = 413
Predicted b/p for carbon 30 – MW of 422.8
3rd order fit, y = 0.000006x3 – 0.0064x2 + 3.0855x – 153.76
b/p=0.000006(422.8)3 – 0.0064(422.8)2 + 3.0855(422.8) – 153.76 = 460
Molecular weight 3rd order as estimator for b/p
Molecular weight and carbon fraction as predictor for b/p
Boiling pt model = 49.5(carbon fractions)0.2791 x (molecular weight)0.5039 -273
This model is based on density function theory and polarized continuum
model done by researcher. Click here to more info
Number
carbon
Molecular
weight
Carbon
fraction b/p
predicted b/p
using model
10 142.28 0.3125 174.1 162
26 366.7 0.325 412 435
30 422.8 0.326 449.7 489
Predicted b/p carbon 26 – using model CF – 0.325, MW – 366.7
y = 49.5(carbon fractions)0.2791 x (molecular weight)0.5039 -273
b/p=49.5(0.325)0.2791 x (366.7)0.5039 - 273 = 435
Predicted b/p carbon 30 – using model CF – 0.326, MW – 422.8
y = 49.5(carbon fractions)0.2791 x (molecular weight)0.5039 -273
b/p=49.5(0.326)0.2791 x (422.8)0.5039 -273 = 489

5. Molecular weight 3rd order as predictor for b/p Molecular weight and carbon fraction model predictor for b/p
Number
carbon
Molecular
weight b/p
predicted
poly fit
3rd order
(% error)
1
2
3
4
5 72.15 36
6 86.18 69
7 100.21 98.4
8 114.23 125.6
9 128.2 151
10 142.28 174.1 173 (0.5%)
11 156.31 196
12 170.33 216.2
13 184.37 234
14 198.39 253.6
15 212.42 270.6
16 226.41 286.9
17 240.4 302
18 254.5 317
19 268.5 330
20 282.5 343
21 296.6 363
22 310.6 368
23 324.6 379
24 338.6 391
25 352.7 403
26 366.7 412 413 (0.2%)
27 378.8 422
28 392.7 431
29 406.8 440
30 422.8 449.7 460 (2%)
Number
carbon
Boiling
point
predicted
(% error)
1
2
3
4
5 36
6 69
7 98.4
8 125.6
9 151
10 174.1 162 (7%)
11 196
12 216.2
13 234
14 253.6
15 270.6
16 286.9
17 302
18 317
19 330
20 343
21 363
22 368
23 379
24 391
25 403
26 412 435 (5.5%)
27 422
28 431
29 440
30 449.7 489 (8.7%)
% error =
(𝑬𝒙𝒑𝒕 𝒗𝒂𝒍𝒖𝒆 −𝑷𝒓𝒆𝒅𝒊𝒄𝒕𝒆𝒅 𝒗𝒂𝒍𝒖𝒆)
𝑬𝒙𝒑𝒕 𝒗𝒂𝒍𝒖𝒆
x 100%
% error =
(𝟏𝟕𝟒.𝟏 −𝟏𝟕𝟑)
𝟏𝟕𝟒.𝟏
x 100% = 0.5%
% error =
(𝑬𝒙𝒑𝒕 𝒗𝒂𝒍𝒖𝒆 −𝑷𝒓𝒆𝒅𝒊𝒄𝒕𝒆𝒅 𝒗𝒂𝒍𝒖𝒆)
𝑬𝒙𝒑𝒕 𝒗𝒂𝒍𝒖𝒆
x 100%
% error =
(𝟏𝟕𝟒.𝟏 −𝟏𝟔𝟐)
𝟏𝟕𝟒.𝟏
x 100% = 7%

6. Molecular weight and carbon fraction model is a weaker fit
Molecular weight model is a better fit
% error, smaller compared to the other model
% error increases as molecular weight increases
3rd order fit – % error changes from 0.5% to 0.2% to 2% as
carbon chain changes from 10 to 26 to 30
y = 6E-06x3 - 0.0064x2 + 3.0855x - 153.76
R² = 0.9998
0
50
100
150
200
250
300
350
400
450
0 50 100 150 200 250 300 350 400
b/p
molecular weight
molecular weight vs b/p
Number
carbon
Molecular
weight b/p
predicted
poly fit
3rd order
(% error)
10 142.28 174.1 173 (0.5%)
26 366.7 412 413 (0.2%)
30 422.8 449.7 460 (2%)
% error, bigger compared to molecular weight model.
% error increases as carbon chains increases
% error changes from 7% to 5.5% to 8.7% as
carbon chain changes from 10 to 26 to 30
Research Question
Which model, molecular weight model, 3rd order, better predictor for b/p.
Which model, molecular weight and carbon fraction model, better predictor for b/p.
Boiling pt model = 49.5(carbon fractions)0.2791 x (molecular weight)0.5039 -273
This model is based on density function theory and polarized continuum
model done by researcher. Click here to more info
Number
carbon
Molecular
weight
Carbon
fraction b/p
predicted
(% error)
10 14228 0.3125 174.1 162 (7%)
26 366.7 0.325 412 435 (5.5%)
30 422.8 0.326 449.7 489 (8.7%)