Practical investigations
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I have done my practical investigation, which is metal + acid, and have used HCl and ethanoic acid and then varied the temperature. I have used temperatures from 5 degrees up to 60 degrees, and measured the gas given off with a gas syringe when the Mg was added, at 10 second intervals.
Now, for each temperature, I have about 10 values - the amount of gas given off at the different time intervals, and I am supposed to plot an Arrhenius graph. I dont think it is in anyway possible to plot one, with the data I have, because from what I have learnt, you plot it according to time taken for the reaction to finish. Is there anyway that I could plot the graph with gas values at different times, or does it have to be time taken for reaction to finish?
Ulex says
I think you have enough data to proceed. Plot your volume-time data for each temperature. You should find that the first part of each graph is more-or-less a straight line. The gradient of each of these straight lines is a measure of the ‘initial rate’ of the reaction at that temperature. Use these rates and temperatures to do an Arrhenius plot.
If the first parts of the graphs are nowhere near straight, don’t worry – just draw a tangent to the graph as close as possible to zero time and use that to get a rate instead.
Risk assessment
Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the risks. You must have these approved by those in authority in your school or college laboratory. Do not rely on what is said on this website.
For further guidance see our tutorial on Risk Assessment.
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updated: 08 November 2007
