Doc Brown's Chemistry KS4 science GCSE/IGCSE Revision Notes
A BRAINSTORM on "Rates of Reaction" for chemistry coursework investigations-projects
Ideas for coursework assignments or projects involving the rates or speed of chemical reactions and is a companion page to see also the DETAILED GCSE Revision Notes on the Factors Affecting the Rates of Chemicals which also has brief descriptions of experimental methods and equations, particle pictures and fully explains all the factors affecting the rate of a chemical reaction
Advanced level chemistry theory pages for GCE/AS/A2/IB and adventurous GCSE students!
and A few health and safety ideas on risk assessment
AIM for a high investigation-project mark - you have nothing to lose for your assessment!e.g. suppose you are investigating the effect of hydrochloric acid concentration on the rate at which the acid dissolves limestone (calcium carbonate)
- BUT you can use and extend these 'brain stormed' ideas to most rates of reaction coursework assignments
- The magnesium/zinc + acid reaction, you can investigate acid concentration and amount of metal
- This web page is meant to teach you how to tackle an coursework e.g. on rates, it is not meant to be copied and the details filled in! Your coursework write-up must expressed in your language and expressed at 'your scientific level'.
- Your teacher will have a good idea what to expect and you must be able to justify all your write-up. Use the sources/references mentioned below and clearly indicate them in your write-up.
- More marks are lost by not writing things down, than by not doing experiments! Your write-up must be your work produced from your study and your experiments. This web page is meant to teach you how to tackle an coursework e.g. on rates, it is not meant to be copied and the details filled in!
- Your coursework write-up must expressed in your language and expressed at 'your scientific level'. Your teacher will have a good idea what to expect and you must be able to justify all your write-up.
- Use the sources/references mentioned below and clearly indicate them in your write-up. More marks are lost by not writing things down, than by not doing experiments!
- EMAIL a query or comment on the rates/coursework ideas pagesbut I do NOT do students coursework for them, neither do I replace your teacher supervisor! however I sometimes get really interesting questions and learn something new myself - and that's always a pleasure!
- A BRAINSTORM outline of a whole investigation is outlined below, it is not meant to be prescriptive, but can form the basis of aiming for a high mark and hopefully give you plenty of ideas.
- For sources and references you should research 'rates of reaction' for theory, experimental methods etc. using textbooks, the Internet, and of course your class work and exercise books and mention your research sources in your coursework report AND QUOTE YOUR RESEARCH SOURCES and ANY PREVIOUS 'RATES' EXPERIENCES
- Any previous 'rates of reaction' experience is invaluable and can be used/quoted in your write-up - particularly knowledge of experimental methods which can count as preliminary work.
- Word process your work if you can and your results can be tabulated and processed into graphs using software packages like Excel
- Preliminary work usually involves doing a few trial runs of the experiment to see how it goes and making modifications if necessary. By writing up how, and why, you have changed the experimental conditions or 'recipes' you can gain more marks.
skill P: Planning - the theory and your experiment design!First, you can start by describing the reaction situation you are intending to investigate e.g. with the word and symbol equation, short description about the reaction, and this sets the scene.
- If you are varying temperature, you need to heat up the reactant solutions separately and take their temperatures, mix, start stopwatch. However, they will cool a little standing out in the laboratory, so not completely satisfactory solution to the problem. In the case of the sodium thiosulphate - acid reaction, you can leave the thermometer in the flask and take the temperature at the end, then use an average for the temperature of the reaction.
- If temperature isn't a variable, it must be kept constant. The simplest solution here, is to make sure all the chemicals have been standing in the laboratory prior to the lesson. Then, they will all be at the same temperature, which should be recorded. If more experiments are conducted at another the time, the temperature must again be checked and recorded.
skill O: Obtaining evidence - observations, measurements, in other words the results! (possibly some data you might have been given)
These must be clearly recorded in neat tables showing all the units e.g.
|Run 3: acid concentration ?????, temperature ????|
|Time ????||Gas volume ????||Gas volume ??? (repeat)||corrected gas volume ???|
- You can produce a summary table with the average/corrected (if necessary) gas volumes v time for all the different acid concentrations or whatever variable
- For the hydrochloric acid - sodium thiosulphate reaction you are recording just the reaction time for different thiosulphate or acid concentrations or temperatures, so the data gathering and subsequent processing is 'simpler'.
- All experiments should be repeated where time allows to check for accuracy and consistency, this may become more necessary after you have done a preliminary analysis
- The 'bung effect'! - look up about dead volumes and its correction when dealing with gas volumes!
- Your recorded results should indicate the accuracy of the measuring equipment e.g. 0- 2 decimal places.
- Some of the work done here in presenting the results, e.g. working out averages etc. actually counts towards the mark for analysing (described below).
- Have you got enough results, do they seem ok? Starting the analysis as soon as possible will help you decide whether further, wider ranging or repeat experiments - best decided after examining the graphs of results (see below) - difficult to decide just looking at tables of data.
skill A: Analysing and considering the evidence - what do the results mean in terms of your prediction and theory!The results are initially processed into graphical form ('graphing') for several reasons for both the analysis and evaluating the experimental .... they can clearly show the general trend of the effect of changing that factor or variable, highlighting experimental 'runs' that don't seem to fit the pattern of the other sets of results for the other runs, individual points that don't seem the pattern of a particular sets of results - BUT ITS UP TO YOU
- For the hydrochloric acid - sodium thiosulphate reaction you can plot either (i) reaction time, or (ii) 1/time versus a concentration or temperature (1/time = relative rate of reaction).
- We are basically talking about plotting the initial rate versus e.g. acid concentration.
- If you are doing something like the hydrochloric acid - sodium thiosulphate reaction, your reaction time measures the formation of a fixed amount of sulphur per 'time'. So the rate is 'x amount of sulphur per time', which means the speed or rate is proportional to 1/time, then plot this 1/time against the concentration of the acid.
skill E: Evaluating - and how good are your results then? error sources? can we improve the existing method? are there other experimental methods?Do your results seem consistent and accurate - always refer directly to the graph or graphs in your analysis ... do any of the sets of results not fit in with the others?, do most/all sets of results fit a pattern?, are there any particular points that don't fit the pattern? (anomalies), can some results be ignored in drawing your conclusion(s)? if so, which results and why? QUOTE DIRECTLY - WITH REFERENCE TO YOUR GRAPH(s)
- For the hydrochloric acid - sodium thiosulphate reaction think about the precipitate, observing it etc.
- e.g. in the case of the sodium thiosulphate - hydrochloric acid experiment , you can use a light gate to detect the precipitate formation. The system consists of a light beam emitter and sensor connected to computer and the reaction vessel is placed between the emitter and sensor. The light reading falls as the sulphur precipitate forms.
- Note that if the temperature of a rates experiment was too low compared to all the other experiments, the 'double error' would occur again, but this time the measured gas volume and the calculated speed/rate of reaction would be lower than expected.
This page should help with rates of reaction coursework projects or assignments investigations
Rate of Reaction
- Length: 1851 words (5.3 double-spaced pages)
- Rating: Excellent
Rate of Reaction Coursework
Aim: To investigate how temperature affects rate of reaction.
Introduction: I am going to investigate how temperature affects the
rate of reaction of hydrochloric acid with calcium carbonate.
This is the reaction that will take place:
Hydrochloric acid + Calcium Carbonate è Calcium Carbonate + Water +
The rate of reaction can be measured in various different ways:
* Using a balance you can check the mass before the reaction and
then after the reaction has taken place. Then check the change in
* You can also use the method of obscuring a cross with sodium
thiosulphate and time which cross becomes invisible first.
I am going to use a syringe to measure the amount of carbon dioxide
given of at regular intervals. This is because it is accurate as the
smallest division on it is 1ml.
The important variables are:
* Temperature – if it is increased the reaction as the particles
will have more energy.
* Number of calcium carbonate chips – if there are a lot of chips
more carbon dioxide will be formed.
* Amount of acid – if there is more acid the rate of reaction will
* Surface area – if the chips have a larger surface area then the
rate of reaction will be faster.
I have chosen to investigate the affect of hydrochloric acid on
calcium carbonate chips. I predict that as the temperature of the acid
increases so will the rate of reaction. This is because for two
substances to react they have to have a successful collision which
means the have to collide with a minimum amount of energy which is
called the activation energy.
This diagram shows how the particles will react with each other with
the minimum amount of energy (activation energy):
The higher the temperature of the acid the faster the acid particles
will be moving around as they’ll have more energy and there will more
collisions. This energy will also allow there to be more successful
collisions and so more carbon dioxide will be formed in smaller amount
of time. Therefore the rate of reaction will be faster.
This diagram shows the reaction of particles with more energy from the
I can also predict that the shape of my final graph of rate of
reaction and temperature will look like this:
From this graph I can predict that as I increase the temperature by
10°C the rate of reaction will double.
Apparatus: 1 Bunsen burner
Calcium Carbonate chips
1 50ml measuring cylinder
1 Wire gauze
1 Conical flask
1 Beaker filled with ice
I chose to use the syringe as it has small divisions to help me make
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Rate Of Reaction Carbonate Chips Activation Energy Carbon Dioxide Calcium Carbonate Collisions Syringe Diagram
an accurate measurement of the amount of carbon dioxide formed. I
chose to use a 50ml measuring cylinder rather than a 100ml one because
it has smaller divisions on it and is therefore more accurate.
1) Set up syringe as shown in the diagram.
2) Measure 50ml of hydrochloric acid, at room temperature, using the
measuring cylinder and pour into conical flask.
3) Immediately put 5 calcium carbonate chips in the acid and seal the
top using the cork on the syringe.
4) Start the stopwatch straight away and record the volume of carbon
dioxide formed every 10 seconds.
5) Repeat the experiment to ensure the results are reliable.
6) Repeat steps 1 – 4 for a range of different temperatures. Use the
beaker filled with ice to cool the acid and the Bunsen burner to warm
To make this a fair test I will control a various variables that will
affect the rate of reaction. I the only variable I will change is the
temperature as this my independent variable. However I have to keep
the all other variables constant. I will use the same number of
calcium carbonate chips every time I repeat the experiment, if I use
more one time and less another time then the rate of reaction will
increase or decrease accordingly. Along with same number of chips I
will try to ensure that the chips that I use have the same surface
area because if the surface area changes so will the rate of reaction.
Also I will use the same amount of acid throughout the experiment
because if there is too much acid the rate of reaction will be fast
but if there is too little then it will be slow. In addition to this I
will ensure that the acid is of the same concentration throughout the
Reliability: To make my results reliable I will repeat the experiment
and find an average volume of carbon dioxide formed at each
temperature. I will also use temperatures ranging from 15 degrees
Celsius to 60 degrees Celsius. Also to make sure I have enough points
on my graph to show a strong correlation I will take 6 readings of
carbon dioxide gas formed at each temperature. When I repeat the
experiment if I have any two points at the same temperature which are
very different I will repeat the experiment and I will use the results
which are closest together to find the average.
Safety: To ensure safety I will wear goggles to protect my eyes from
the acid. I will also wash my hands after using the acid as it is an
Preliminary: From my preliminary work I learnt that if the temperature
of the acid is too low then it doesn’t react with the calcium
carbonate and no carbon dioxide gas is given off. I also found out
that if the temperature is too high the calcium carbonate reacts too
quickly and we can’t make enough readings of carbon dioxide formed.
This is why I am using the range of temperatures from 15 – 60 degrees
I also realised if I use small chips of marble they react too quickly
as well and as temperature increases it isn’t possible to make enough
readings of carbon dioxide formed. This is because the smaller the
surface area the higher the rate of reaction.
I worked out the rate of reaction by choosing a point on my line or
curve of best fit and then dividing the volume by the temperature (the
initial gradient). I used these results to draw my graph of rate of
reaction and time.
Conclusion: In my graphs of temperature and volume of carbon dioxide
formed the line of best fit shows an increase of carbon dioxide
formed. Also if I compare the line of best fit I can see that the
graphs with the higher temperatures have a steeper line. On the graph
of rate of reaction and temperature the shape shows the doubling of
the rate of reaction. From this I can conclude that as the temperature
of the hydrochloric acid increases so does the rate of reaction.
The reason for the rate of reaction increasing with the temperature
is, as the acid gets hotter the energy of the acid particles
increases, therefore causing more successful collisions. For a
successful collision to take place the acid particles must have a
minimum amount energy called the activation energy. With this energy
the acid particles can collide and react with the calcium carbonate
particles, but if the acid particles don’t have the activation energy
even if they collide with chips a reaction won’t take place. I know
that the activation energy for this reaction was approximately 15°c; I
know this because if the temperature was any lower than this no carbon
dioxide would be formed. Therefore as I increased the temperature the
particles gained more energy and had more successful collisions with
the calcium carbonate chips, this increased the amount of carbon
My graph of rate of reaction agrees with my prediction because as the
temperature increases so does the rate of reaction and from my line of
best fit it is possible to see that as the temperature increases by
10°C the rate of reaction approximately doubles. For example when the
temperature is 25°C the rate of reaction is 0.34ml/s and when the
temperature increases to 35°C the rate of reaction doubles to
0.68ml/s. This proves my quantitative prediction to be correct; as the
temperature increases the rate of reaction doubles.
Also my other graphs of amount of carbon dioxide formed and
temperature also agree with my prediction. This is because on the
graphs with higher temperatures the line of best fit is steeper and so
the initial gradient is higher, this proves that as the temperature
increases so does the rate of reaction.
Evaluation: I think that my measurements were quite accurate but not
completely because if they were there wouldn’t be any anomalous points
on my graphs. I think that the syringe I used was accurate because its
smallest division was 1ml. Also my measuring cylinder was accurate as
it was a 50ml measuring cylinder and again it had small divisions of
1ml, if I had used a larger measuring cylinder it wouldn’t be as
accurate because the divisions on it would be bigger. However whilst
making measurements I might’ve made a few human errors. Also when I
was measuring the volume of carbon dioxide formed sometimes it was
difficult to read the amount formed as it was in between the small
divisions so I had decide which millilitre it was closest to, this
might caused error as the measurement wasn’t exact. Also when I
measured the acid I tried to use the lower meniscus but in some cases
I forgot to check and so some measurements might not have been
completely accurate. Furthermore when I added I chips of calcium
carbonate to the acid they started to react straight away but I
couldn’t put the bung in straight away due to my slightly slow
reaction time, this is one of the human errors that I caused.
To get more reliable results I could’ve repeated my experiment again
to get a more reliable average. Some of my averages weren’t reliable
because when I repeated the experiment for the second time the first
and second time the results were not similar.
I might have some incorrect results because my evidence isn’t
completely reliable. The reason for this is, I only measured the
volume of carbon dioxide formed for 60 seconds, and to make my
evidence more reliable could have taken more measurements so I could
draw firmer conclusions.
To improve my experiment I could have used a balance to measure the
change in mass of the acid and calcium carbonate chips. This would
have been more accurate because I wouldn’t have to worry about carbon
dioxide escaping before I put the bung on. Another reason this method
would be more accurate is because when I counted the chips some were
different sizes and this made my results slightly less reliable.
However if I could weigh the chips then I would know the exact mass of
calcium carbonate that I started with. Therefore I could use the same
mass of calcium carbonate every time and this would make my results