Tripod Method Firstly I will draw a small dark cross on a piece of paper and place it on a bench mat. I will then put 40cm3 of sodium thiosulphate into a conical flask and place it on a tripod and gauze. I will heat the solution for a few minutes until the desired heat is reached, i. Next I will place the conical flask on top of the cross, pour 5cm3 of hydrochloric into the hot sodium thiosulphate solution and time how long it takes for the cross to disappear.
Planning - the theory and your experiment design! For example, with the word and symbol equation, short description about the reaction, and so on.
This sets the scene. If you are confident and chosen the VARIABLE you want to investigate you should try to make a quantative prediction and maybe justify it with some theory if you can.
You can continue in a broader context by introducing some background theory and descriptions of the factors or VARIABLES which may have an effect on the rate of the reaction you are studying include briefly factors which might not apply.
In your 'method' description use the correct units or descriptors. The factors to discuss might be: Example of the theory is the factors will increase the molecules inside the chemical and it will eventually increase the rate of reaction.
Is there any other factor for the reaction you are studying? If you have decided, for example, to investigate the effect of acid concentration on the speed of a reaction, then everything else should be kept constant for a fair test, and this should be obvious in your plan for the reasons discussed above!
If you haven't already chosen the VARIABLE, do so now, and make a prediction and justify it with some theory which you may have previously described and should refer to. If a gas is formed, there are at least two ways of collecting a gas e. The hydrochloric acid - sodium thiosulphate reaction depends on the time for a certain amount of sulphur precipitate to form and obscuring a marked black X on white paper.
Briefly explain how the method can be used to measure the speed - the results of the first few minutes is usually the most crucial - you can discuss briefly other methods, but perhaps better in evaluation as a means of further evidence. When you have decided on the method, give a detailed description of how you might carry it out.
Clearly indicate why the method would be expected to produce precise and reliable evidence - the results! Complete a full risk assessment. If you are looking at changing the reaction temperature, its not easy to accurately vary and control the temperature of the reactants without a thermostated water bath to hold the reaction flask in.
Even with a thermostated water bath normally only available to advanced level studentsall the reactant solutions should be pre-warmed in the bath before mixing and start the timing and recoding of results.
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. Refer to any previous laboratory experience with 'rate of reaction' experiments which may have helped you decide and design the experimental method.
A clearly labelled diagram of the method with a brief outline of how you intend to carry out the experiments - this cuts down on the writing and makes the scene clear! You must give details of how long you might time the experiment as well as the time interval between experimental readings REMEMBER you can change your 'recipe' or way of doing the experiment.
Obtaining evidence[ edit ] Observations, measurements, in other words the results! Possibly some data you might have been given secondary data These must be clearly recorded in neat tables showing all the units e. Repeat corrected gas volume???
All experiments should be repeated where time allows checking for accuracy and consistency; this may become more necessary after you have done a preliminary analysis The 'bung effect'! Your recorded results should indicate the accuracy of the measuring equipment e.
Some of the work done here in presenting the results, e. 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.
Analysing and considering the evidence[ edit ] 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 It is best, if possible, to have all the average results points plotted on the same graph for easy comparison - take care because this may involve 4 or 5 lines for 4 or 5 different acid concentrations Make sure you use a clear KEY for the different line points and a clear title for the graph AND clearly label the axis including the units or whatever.
Use smooth 'best curves' for as many of the points as possible, though some parts of the graph might be linear, watch out for the 'scatter' - the experiment is not that easy to get good results.
See Rates of Reaction Notes. From the graph you can then describe in words what the results mean, always refer to the graph lines and gradients directly - don't make vague comments. So what we are after is the main 'trend s ' or 'pattern s ' describing with reference to the graphs.
Does the 'trend' of all the graph lines support you're your prediction, are all the results consistent with your prediction AND theory?The hydrochloric acid should be about 1M for a reasonable rate of reaction.
Each experiment run will need 50 cm 3. Though low hazard, eye protection is necessary as you may get a . I am going to investigate how the rate of the reaction between sodium GCSE Chemistry Coursework Investigation] Free Essays words ( pages) Investigating Rates of Reactions Essay Method: I will carry my experiment as follow: 1.
For safety I will wear goggles.
In order to get maximum marks in this coursework it is vital that you discuss all factors which affect the rate of a reaction. These include: Temperature.
In order to get maximum marks in this coursework it is vital that you discuss all factors which affect the rate of a reaction. These include: Temperature. 3 Rates of reactions science (chemistry) coursework My coursework is based on rates of reaction.
This deals with the time taken for reactants to be changed into products, when the . 1 Introduction My investigation is about the rate of reaction. A rate of reaction is defined as how fast or slow a reaction takes place.
For example, the oxidation of iron under the atmosphere is a slow.