rates of reaction

6.1 Collision theory and rates of reaction

Understanding

Species react as a result of collisions of sufficient energy and proper orientation.
The rate of reaction is expressed as the change in concentration of a particular reactant/product per unit time.
Concentration changes in a reaction can be followed indirectly by monitoring changes in mass, volume, and colour.
Activation energy (Ea) is the minimum energy that colliding molecules need in order to have successful collisions leading to a reaction.
By decreasing Ea, a catalyst increases the rate of a chemical reaction, without itself being permanently chemically changed.

Applications and skills

Description of the kinetic theory in terms of the movement of particles whose average kinetic energy is proportional to temperature in Kelvin.
Analysis of graphical and numerical data from rate experiments.
Guidance: Calculation of reaction rates from tangents of graphs of concentration, volume, or mass vs time should be covered.
Students should be familiar with the interpretation of graphs of changes in concentration, volume, or mass against time.
Explanation of the effects of temperature, pressure/concentration, and particle size on rate of reaction.
Construction of Maxwell–Boltzmann energy distribution curves to account for the probability of successful collisions and factors affecting these, including the effect of a catalyst.
Investigation of rates of reaction experimentally and evaluation of the results.
Sketching and explanation of energy profiles with and without catalysts

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Additional resources

The Coldest Reaction

Student cooking lab - Maillard reaction - bakery (Exploration and Evaluation)

The Maillard reaction is occurring everyday in the kitchen if you cook a steak, for example, of back cookies. Let's investigate how we can control the rate of this reaction.

Link to pdf of Maillard reaction - bakery

Video of the Maillard reaction - Bakery

Task:

Check out the poster and watch the video above
Plan your own practical which investigates how to speed up the maillard reaction (use IBDP Exploration criterion) - consider the following 3 factors:

Change of Heat
Change of Concentration
Change of pH

Conduct your cooking lab (it is important to note that you are only able to measure the rate qualitative by observing the colour of the bakery). Be sure to video record your practical.
Produce a table of results
Evaluate your method (use IBDP Evaluation) criterion
Complete your video of your student lab, which should contain the following:

Introduction to your experiment (explain what you are going to do and state your research question, Variables and equipment/ingredients)
Video footage of the actual practical with your step by step method as caption
Conclusion to your experiment (show your table to results, as well as pictures/video of your results and explain in short strength and weaknesses of the practical as well as improvements)

Use Flipgrid to upload your video (max 10min)
Give peer feedback

Link to Flipgrid

How to speed up chemical reactions

Student cooking lab - Baking soda and Vinegar (Analysis)

The reaction of Baking soda and vinegar is another very common reaction in the kitchen.

Task:

Watch the video of the experiment
Understand the raw quantitative data in the poster below
Analyse the data in a lab report. Be sure to include:

Data table of volume carbon dioxide vs time
Data table of Volume of carbon dioxide vs mass of Baking soda (Concentration)
Plot a graph for each table
Calculate the rate of reaction at 8(s) for 4g as well as 8g
Find literature value
Determine absolute uncertainty and if possible the percentage error
Be sure to propagate your error when you are calculating the rate

Link to poster

Rate of reaction - theory

Task:
Watch the videos and complete the tasks within the video.

flipped classroom

Factors affecting the rate - student presentation

There are a number of factors that can effect the rate of reaction:

Temperature
Concentration
Pressure
Surface area
Catalyst

Task:

Research how of of the 5 factor impact the rate of reaction
Create a ppt/slides to present the information that you have researched and share it by putting it in the folder below. Please consider the following: