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Investigate the effect of concentration on rate of reaction
Background Information and Keywords
Background Information and Keywords
Keywords
Keywords
- Concentration - A measure of how much solute is dissolved in the solvent. Units g/cm3
- Collision Theory - The theory explaining how particles react. To react particles need to be able to collide with sufficient energy (activation energy) and with the correct orientation
- Activation Energy - The minimum energy required for a collision between particles to be successful and a reaction to take place
- Rate of Reaction - A measure of how fast a reaction occurs over a specific time. Units are g/s or cm3/s
Background Information
Background Information
In order for a reaction to take place, chemical particles must be able to collide with sufficient energy and with the correct orientation. This is called "collision" theory.
The speed at which a reaction happens is called the "rate of reaction"
There are 4 factors which can affect the rate of reaction:
Concentration (liquids)/ Pressure (gasses)
Surface area (solids)
Temperature
Adding a catalyst
We can measure the rate of reaction using different practicals. We can measure rate by:
Collecting and measuring the volume of gas produced by a reaction over time
Measuring the loss of mass of a reaction over time
Timing how long it takes for a reaction to change colour
Other things you need to be able to do
Other things you need to be able to do
To do the practical
To do the practical
Know how to read a scale on a measuring cylinder or gas syringe
Know how to keep time using a stopwatch
Be able to measure volumes and masses of chemicals accurately
Be able to repeat an experiment accurately
To handle the data and make conclusions
To handle the data and make conclusions
Be able to draw a table of results
Be able to draw a graph with suitable axis from experimental data
Be able to draw a line of best fit for a set of data points
Be able to calculate the mean rate of reaction from data
Be able to convert between minutes and seconds and cm3 and dm3
Be able to draw tangents to curved lines
Be able to calculate a gradient for a tangent of a line
"How To Do It" Video
"How To Do It" Video
Watch this video to remind yourself how this practical is carried out.
What are the key steps to this practical?
What are the pieces of equipment called?
Why are these pieces of equipment used?
Diagrams
Diagrams
There are two key practicals here. One where we collect the gas given off by a practical over time. One where we time how long it takes for a reaction to change colour. You need to be able to describe how to do both of them.
Practical 1: Measuring the colour change of a reaction
Practical 1: Measuring the colour change of a reaction
Key Steps
Key Steps
Measure a volume of sodium thiosulfate using a measuring cylinder and pour it into the conical flask.
Place the conical flask on top of a piece of paper with a cross on it.
Measure the dilute acid using a measuring cylinder
Add the acid to the conical flask and start the stopwatch.
Look at the cross from directly above the conical flask.
Stop the stopwatch when the cross has completely disappeared.
Repeat the experiment with different concentrations of acid.
Practical 1: Collecting the gas formed during a reaction.
Practical 1: Collecting the gas formed during a reaction.
Key Steps
Key Steps
Measure a volume of acid using a measuring cylinder and pour it into a conical flask.
Set up your gas syringe or measuring cylinder to collect the gas. Make sure that it's starting at 0 before starting the experiment.
Add the magnesium/reactant to the conical flash and start the stop watch. Quickly replace the bung to prevent gas escaping.
Measure the volume of gas produced every unit of time (e.g. 20 secs, 30 secs, 1 min) until the reaction finishes.
Repeat the experiment for a different concentration of acid.
Key Questions from this Practical
Key Questions from this Practical
What is the independent variable in this practical (the thing that's changed)?
What is the dependent variable in this practical (the thing that's measured)?
What are the control variables for this practical (the things which are kept the same)?
How could the practical be improved?
Where are the major sources of error/ what could go wrong in this practical which would lead to bad results?
How would you draw a graph for your set of data collected from this practical?
How would you draw a line of best fit for your data?
What does the shape of the graph tell you about how the rate of reaction changes over time?
How would you calculate the mean rate of reaction?
How would you draw a tangent to your curve at a specific time?
How would you work out the instantaneous rate of reaction at a specific time (H)?
How would the shape of your rate graph change if we decreased temperature/increased surface area/added a catalyst?
Question Practice and Exam Questions
Question Practice and Exam Questions
Required Practicals Mastery Booklet - PAG 5 - Measuring Rate of Reaction.pdfPAG 5: Mastery Question Booklet
PAG 5: Mastery Question Booklet
This Mastery Booklet is filled with questions and exam questions to help you master this core practical. All answers and mark schemes are attached at the end.
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