Tilia Posted May 31, 2009 Report Share Posted May 31, 2009 We did a lab where we were supposed to find the order of reaction of the reaction between magnesium and hydrochloric acid from measuring the volume of gas formed vs time. I've drawn a graph, found the logarithmic function and now I need to find the initial rates. I know that the initial rate is the initial gradient, but what's the best way of finding it?I haven't learned calculus yet, so I'm not expected to use derivatives. I thought about treating the first and second measured value as a straight line and hence find the slope, but that will be over a comparatively large time period. Is it better to use the function to interpolate a value inbetween and thus get a smaller time interval?If so, how do I treat the uncertainties while taking the log?I've never scored full marks on DCP, so please help me! Reply Link to post Share on other sites More sharing options...
Sandwich Posted June 3, 2009 Report Share Posted June 3, 2009 (edited) I may be taking this totally the wrong way, but you can straight-line-ify it and therefore make finding gradients pretty simple by either taking 1/T or I think you can also do it using logarithmic values. Either way, you should change it into a straight line that way.EDIT: I should add, we did a similar experiment and all the different graphs, their shapes and their axes ought to be in your textbook. I found it all there. Edited June 3, 2009 by Sandwich Reply Link to post Share on other sites More sharing options...
Tilia Posted June 4, 2009 Author Report Share Posted June 4, 2009 Thanks. I did draw a tangent by hand and found the gradient that way. But has the rate of reaction/concentration graph to be through the origin? Reply Link to post Share on other sites More sharing options...
Sandwich Posted June 4, 2009 Report Share Posted June 4, 2009 I'd guess so. After all, prior to the reaction occuring, the rate was 0. Reply Link to post Share on other sites More sharing options...
Tilia Posted June 6, 2009 Author Report Share Posted June 6, 2009 I'd guess so. After all, prior to the reaction occuring, the rate was 0.Damn it Reply Link to post Share on other sites More sharing options...
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