7.2Reactivity 3 — What are the mechanisms of chemical change?
Tool 2: Technology — IB Chemistry SL Revision Notes & Topical Questions
5 min read 10 parts Lesson 6 of 12 Unit quiz
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
Lesson summary
7.2 Tool 2: Technology — IB SL Notes — IB CHEMISTRY SL notes: Use data loggers, sensors, databases, models, simulations and spreadsheets to collect and process data in chemistry.Computational chemistry — uses computer simulations and mathematics to study chemicals and how they re…
- Sources of large data sets
- Processing
- Measurements
- Advantages
- Definition
- Temperature probe
Part 1 of 8Computational chemistry and data
Computational chemistry and data
Computational chemistry
- Computational chemistry uses computer simulations and mathematics to study chemicals and how they react.
Purpose
- Purpose it helps scientists spot trends and make predictions, such as reactivity or properties of substances.
Sources of large data sets
- Sources of large data sets experiments, sensors, existing databases, and computer models and simulations.
Part 2 of 8Data loggers
1Function
- Function a data logger collects data quickly and accurately and stores it in a computer, often as a table.
2Processing
- Processing the computer can calculate averages, draw graphs and find gradients more precisely than a person.
- (rates of change)
3Measurements
- Measurements temperature, pressure, pH or conductivity through connected sensors.
4Display
- Display results appear on a screen in real time.
5Advantages
- Advantages many readings in a short time, less human reaction-time and parallax error, and several variables logged at once.
Part 3 of 8Sensors
Definition
Definition an input device that detects a specific change in its surroundings and converts it into an electrical signal stored by the data logger.
Benefit
- Benefit lets chemists collect large data sets in a short time.
Temperature probe
- Temperature probe replaces a thermometer in calorimetry and monitors exothermic and endothermic reactions.
Pressure sensor
- Pressure sensor measures gas or liquid pressure, in gas law experiments or reactions that change pressure.
Conductivity sensor
- Conductivity sensor relates conductivity to ion concentration, studies electrolytes and follows reaction rate when ions are made or used.
Part 4 of 8pH meters
Construction
- Construction a reference electrode that gives a constant reading and a glass-membrane electrode that responds to H+ ions.
Operation
- Operation the meter compares the two electrodes and displays the pH.
Uses
- Uses finding the end point of acid-base titrations, studying acids, bases and salts, and testing how well buffers resist pH change.
Calibration
- Calibration a pH meter is calibrated with buffer solutions before use.
Part 5 of 8Databases
Databases
Definition
Definition a structured collection of data that can be searched, sorted, filtered and analysed quickly.
Types of data
- Types of data formulae of polyatomic ions, melting and boiling points, enthalpies, entropies and Gibbs energies, rate constants, equilibrium constants, NMR and IR spectra, structures, bond lengths and organic synthesis conditions.
| Database | Content |
|---|---|
| Spectral Database for Organic Compounds | Formula, mass, structure and 13C NMR, 1H NMR and IR spectra |
| MolCalc | 3D molecules with enthalpy, heat capacity, entropy, vibrational frequencies, orbitals and polarity |
| PubChem | Structures, names, chemical and physical properties of a very large number of chemicals |
| ChemSpider | Chemical properties and spectra |
| NIST WebBook | Formulae, properties and reaction searches |
Part 6 of 8Models and simulations
Model
Model a simplified version of reality, such as the ball-and-stick model of bonds and angles.
Approximation
- Approximation every model involves some simplification and loss of accuracy, however powerful.
Simulation
- Simulation uses models based on chemical principles to predict the behaviour of atoms, molecules and systems.
Value
- Value explores scenarios that are unsafe or impractical,
- such as the violent reactions of heavy Group 1 metals with water, predicted from lighter ones.
Variable control
- Variable control users alter variables, e.g. temperature, pressure and volume of a gas, and collect data from the predictions.
Reliability
- Reliability depends on the quality of the models and assumptions.
Online resources
- PhET has simulations of molecular shapes, the pH scale and states of matter.
Part 7 of 8Processing data with spreadsheets and graphs
Organisation
- Organisation enter raw data and arrange it by parameter in rows and columns.
Manipulation
- Manipulation perform calculations, statistics and mathematical operations on data sets.
Visualisation
- Visualisation built-in functions produce graphs that reveal trends,
- such as first ionisation energy against atomic number or pH against volume of acid.
Graph types
- Graph types line graphs and scatter plots show trends and correlations, while bar graphs and pie charts compare data.
Direct recording
- Direct recording output from a digital pH probe can be fed straight into a spreadsheet to plot a graph.
Calibration curve
- Calibration curve a line graph of absorbance against known concentrations lets the concentration of an unknown be read from its absorbance.
Part 8 of 8Modelling and visualisation tools
1Computational models
- Computational models give insight into complex processes while saving time and resources compared with experiments alone.
2Molview
- Molview free software that builds structures and shows them in 3D.
3Visualisation
- Visualisation interactive 3D tools help in exploring structures and behaviour.
4Reaction pathways
- Reaction pathways graphs of pathways and kinetic data help elucidate mechanisms.
5Use in assessment
- Use in assessment look for chances to use spreadsheets, graphs and modelling in practical work.
Key terms
| Term | Meaning |
|---|---|
| Data logger | A device that records and stores data from sensors, usually on a computer. |
| Sensor | An input device that converts a physical or chemical change into an electrical signal. |
| Database | A structured collection of data that can be searched and analysed. |
| Model | A simplified version of reality used to explain or predict behaviour. |
| Simulation | A model-based prediction of how a system behaves when variables are changed. |
| Calibration curve | A graph of absorbance against known concentrations. |
Avoid these mistakes
1
Treating a simulation as exact — all models simplify reality.
2
Using an uncalibrated pH meter — calibrate with buffers first.
3
Assuming a data logger removes all error — sensor calibration and response time still matter.
4
Using a graph type that hides the trend — choose line or scatter graphs for relationships.
Last updated:
\n