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Integrating Virtual Labs into the AP/IB Chemistry Curriculum
Kumar Venkat
Science By Simulation www.sciencebysimulation.com
Questions
• What are virtual labs?
• How do they align with AP/IB chemistry?
• How can I set up & run virtual experiments?
• Why should I use virtual labs?
• How can I assign and assess virtual labs?
What are virtual labs?
• Based on simulation tools & technologies
• Common in industry, still new to academia
• Run experiments through a web browser
• Easy to generate data and report results
Simulation tools used
• Two web apps, both available free:
– ChemReaXTM: chemical reaction simulator
• www.sciencebysimulation.com/chemreax
– GasSimTM: gas law simulator
• www.sciencebysimulation.com/gassim
Demonstration topics
• Equilibrium – Effect of temperature/pressure changes (Le Chatelier’s principle)
– AP: unit 10; IB: unit 7
• Kinetics – Reaction order, rate constant, half life
– AP: unit 9; IB: unit 6
• Acid-Base Titration – Polyprotic acids, hydrolysis
– AP: unit 11; IB: unit 8
• Gas Laws – Real gases, deviations from ideal gas law
– AP: unit 4; IB: unit 1
Equilibrium Effect of temperature, exothermic reaction
• Reaction: Methanol synthesis
CO (g) + 2H2 (g) ⇌ CH3OH (g)
• Virtual Experiment:
Simulate the reaction in ChemReaX under different temperatures and collect data Initial partial pressures: P(CO) = 10 bar; P(H2) = 1 bar ;
P(CH3OH) = 0.1 bar
Plot the final composition and free energy vs. temperature
ChemReaX
Equilibrium Effect of temperature, exothermic reaction
0
0.2
0.4
0.6
0.8
1
1.2
1.4
-60
-40
-20
0
20
40
60
200 300 400 500 600
Fin
al P
arti
al P
ress
ure
s (
bar
s)
Fre
e E
ne
rgy
Ch
ange
(K
J)
Temperature (K)
As temperature increases, equilibrium shifts to the left towards reactants
Standard free-energy change
CH3OH
H2
Equilibrium Effect of temperature, endothermic reaction
• Reaction:
H2 (g) + CO2 (g) ⇌ H2O (g) + CO (g)
• Virtual Experiment:
Simulate the reaction in ChemReaX under different temperatures and collect data Initial partial pressures: P(H2) = P(CO2) = 1 bar; P(CO) = P(H2O) = 0.1 bar
Plot the final composition and free energy vs. temperature
ChemReaX
Equilibrium Effect of temperature, endothermic reaction
0.0
0.2
0.4
0.6
0.8
1.0
1.2
-10
-5
0
5
10
15
20
25
30
35
200 300 400 500 600 700 800 900 1000 1100 1200 1300
Fin
al P
arti
al P
ress
ure
s (
bar
s)
Fre
e E
ne
rgy
Ch
ange
(K
J)
Temperature (K)
As temperature increases, equilibrium shifts to the right towards products
Standard free-energy change
CO
CO2
Equilibrium Effect of pressure
• Reaction:
CO (g) + 2H2 (g) ⇌ CH3OH (g)
• Virtual Experiment:
Simulate the reaction in ChemReaX under different pressure factors and collect data Initial partial pressures: P(CO) = 1 bar; P(H2) = 2 bar; P(CH3OH) = 0.1 bar
Plot the final composition vs. pressure factor
ChemReaX
Equilibrium Effect of pressure
0.94
0.96
0.98
1.00
1.02
1.04
1.06
1.08
1.10
1.12
0.00
0.05
0.10
0.15
0.20
0.25
0.1 0.5 1 2 10 Fin
al N
orm
aliz
ed
Par
tial
Pre
ssu
re
- P
rod
uct
(b
ars)
Fin
al N
orm
aliz
ed
Par
tial
P
ress
ure
s -
Re
acta
nts
(b
ars)
Pressure Factor
As pressure increases, equilibrium shifts to the right to reduce the number of moles of gas
CO
H2
CH3OH
Kinetics Effect of reaction order
• Reaction:
H2 (g) + I2 (g) ⇌ 2HI (g)
• Virtual Experiment:
Simulate the reaction kinetics modeled as first/second/third order and collect data Initial partial pressures: P(H2) = 0.5 bar; P(I2) = 0.6 bar; P(HI) = 0
Temperature: 721K
Plot the reaction progress vs. time
ChemReaX
Kinetics Effect of reaction order
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
0.00 0.19 0.37 0.56 0.75 0.94 1.12 1.31 1.50 1.68 1.87
Par
tial
Pre
ssu
res
(bar
s)
Time (seconds)
First Order (k=1, X=1, Y=0, Z=0)
H2
I2
HI
Kinetics Effect of reaction order
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
0.00 0.65 1.30 1.95 2.60 3.25 3.89 4.55 5.20 5.85 6.49
Par
tial
Pre
ssu
res
(bar
s)
Time (seconds)
Second Order (k=1, X=1, Y=1, Z=0)
H2
I2
HI
Kinetics Effect of reaction order
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
0.00 4.48 8.95 13.45 17.93 22.39 26.86 31.33 35.83 40.34 44.75
Par
tial
Pre
ssu
res
(bar
s)
Time (seconds)
Third Order (k=1, X=2, Y=1, Z=0)
H2
I2
HI
Kinetics Effect of rate constant
• Reaction:
CO (g) + 2H2 (g) ⇌ CH3OH (g)
• Virtual Experiment:
Simulate a second-order reaction in ChemReaX , vary the rate constant, collect data Initial partial pressures: P(CO) = P(H2) = 1 bar; P(CH3OH) = 0
Temperature: 298.15K
Plot the reaction progress vs. time
ChemReaX
Kinetics Effect of rate constant
0.00
0.20
0.40
0.60
0.80
1.00
1.20
0.00 0.87 1.74 2.61 3.48 4.35 5.22 6.09 6.96 7.83 8.70
Par
tial
Pre
ssu
res
(bar
s)
Time (seconds)
Second Order (k=0.5, X=1, Y=1, Z=0)
CO
H2
CH3OH
Kinetics Effect of rate constant
0.00
0.20
0.40
0.60
0.80
1.00
1.20
0.00 0.22 0.44 0.65 0.87 1.09 1.31 1.52 1.74 1.96 2.17
Par
tial
Pre
ssu
res
(bar
s)
Time (seconds)
Second Order (k=2, X=1, Y=1, Z=0)
CO
H2
CH3OH
Kinetics Half lives of reactants
• Reaction:
N2 (g) + 3H2 (g) ⇌ 2NH3 (g)
• Virtual Experiment:
Simulate as first and second order reactions, vary the initial partial pressure of H2, and note the half lives of H2 Initial partial pressures: P(N2)= 10 bar; P(NH3) = 0
Temperature: 298.15K
Plot the half lives of H2 vs. reaction order and initial partial pressure
ChemReaX
Kinetics Half lives of reactants
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
1 2
Hal
f Li
fe o
f H
2 (
seco
nd
s)
Reaction Order
Half life of reactant depends on initial partial pressure if reaction order > 1
Initial P(H2) = 1
Initial P(H2) = 2
Acid-Base Titration Effect of Titrand Concentration
• Reaction:
Titrand: CH3CO2H; Titrant: NaOH
• Virtual Experiment:
Run titration simulations in ChemReaX with varying titrand concentrations Titrand volume = 1L; Titrant concentration = 1M
Plot the pH curves side-by-side
ChemReaX
Acid-Base Titration Effect of Titrand Concentration
0
2
4
6
8
10
12
14
16
0
0.0
8
0.1
6
0.2
4
0.3
2
0.4
0.4
8
0.5
6
0.6
4
0.7
2
0.8
0.8
8
0.9
6
1.0
4
1.1
2
1.2
1.2
8
1.3
6
1.4
4
1.5
2
1.6
1.6
8
1.7
6
1.8
4
1.9
2
2
pH
Titrant Volume (L)
Equivalence point moves to the right as the titrand concentration increases
0.25M
0.5M
0.75M
1M
1.25M
1.5M
Acid-Base Titration Comparing different acids
• Reaction:
Titrands: CH3CO2H, H2SO4, H2SeO3, H3BO3; Titrant: NaOH
• Virtual Experiment:
Run titration simulations of each titrand against the titrant using ChemReaX Titrand volume = 1L; Titrand/titrant concentrations = 1M
Plot the pH curves side-by-side
ChemReaX
Acid-Base Titration Comparing different acids
0
2
4
6
8
10
12
14
16
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2
2.1
2.2
2.3
2.4
2.5
pH
Titrant Volume (L)
First ionization is neutralized when the titrant volume is about 1L, and the second ionization at approximately 2L
Very weak polyprotic acid: H3BO3
Weak polyprotic acid: H2SeO3
Weak acid: CH3CO2H
Strong polyprotic acid: H2SO4
Acid-Base Titration Effect of hydrolysis
• Reaction:
Titrand: H2SeO3; Titrant: NaOH
• Virtual Experiment:
Run a titration simulation of titrand against the titrant using ChemReaX Titrand volume = 1L; Titrand/titrant concentrations = 1M
Plot the pH curve with and without hydrolysis
ChemReaX
Acid-Base Titration Effect of hydrolysis
0
2
4
6
8
10
12
14
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2
2.1
2.2
2.3
2.4
2.5
pH
Titrant Volume (L)
Hydrolysis speeds up the neutralization of this polyprotic acid and accelerates the pH change
With hydrolysis
Without hydrolysis
Gas Laws Deviation from the ideal gas law
• Virtual Experiment:
In a fixed volume of 1L, vary the number of moles of CO2
Run GasSim simulations for temperatures below and well above the critical temperature Tc for CO2 (304K)
Plot pressure vs. number of moles for the ideal gas law and “ real” gas laws
GasSim
Gas Laws Deviation from the ideal gas law
0
10
20
30
40
50
60
70
80
0.0
5
0.1
7
0.2
9
0.4
1
0.5
3
0.6
5
0.7
7
0.8
9
1.0
1
1.1
3
1.2
5
1.3
7
1.4
9
1.6
1
1.7
3
1.8
5
1.9
7
2.0
9
2.2
1
2.3
3
2.4
5
2.5
7
2.6
9
2.8
1
2.9
3
Pre
ssu
re (
bar
s)
Number of Moles
T = 273K < TC: Inter-molecular attractive forces dominate at higher gas densities and reduce the pressure in “real” gas
models
Ideal Gas Model
van der Waals Gas Model
Peng-Robinson Gas Model
Gas Laws Deviation from the ideal gas law
0
20
40
60
80
100
120
140
160
0.0
5
0.1
7
0.2
9
0.4
1
0.5
3
0.6
5
0.7
7
0.8
9
1.0
1
1.1
3
1.2
5
1.3
7
1.4
9
1.6
1
1.7
3
1.8
5
1.9
7
2.0
9
2.2
1
2.3
3
2.4
5
2.5
7
2.6
9
2.8
1
2.9
3
Pre
ssu
re (
bar
s)
Number of Moles
T = 600K > TC: Both ideal and “real” gas models predict similar pressures -- inter-molecular attractive forces are mostly
overcome by the higher kinetic energy
Ideal Gas Model
van der Waals Gas Model
Peng-Robinson Gas Model
Why use virtual labs?
• Integrate demonstrations into lectures
• Supplement textbooks and real labs
• Bring textbook concepts to life
• Enable students to learn by doing
• Meet specific learning targets
• All at no cost to you or your students
Assigning and assessing virtual labs
• Can go beyond conventional lab reports
• Structure as quizzes in Google Forms: – guided sequence of experiments with questions to
answer along the way
– students run multiple simulations, collect data and perform additional calculations/analysis
– students get quick feedback and scores
– assign in-class or as homework
• Sample exercises: www.sciencebysimulation.com/chemreax/Exercises.aspx
