m.k.2015 Posted February 10, 2014 Report Share Posted February 10, 2014 Hello everyone, I am stuck here and need urgent help. We had to design an internal assessment about viscosity, therefore I decided to investigate how viscosity is affected as the number of Carbons in a homologous series increase. Hence, I just calculated the time taken for 15 ml of each solution to drop of a burette. The problem is, I do not think that this is hard enough! and I believe that calculating the time only would not get me top marks, so am I right? The other thing is that I am really stuck on the uncertainties, I have only used a stopwatch, a burette, and a beaker to measure the amount of solution I have .. How do I calculate my uncertaintyPlease help asap, Thank you so much in advance Reply Link to post Share on other sites More sharing options...
Orientflower Posted February 10, 2014 Report Share Posted February 10, 2014 well to calculate uncertainty you need to find the percentage errors of the apparatus u used during the data collection and then change them to absolute valuethe formula of the percentage error = ( uncertainty divided by the actual measurement) * 100% Reply Link to post Share on other sites More sharing options...
bluedino Posted February 10, 2014 Report Share Posted February 10, 2014 I did viscosity for one of my IAs and used time to represent that. I lost the majority of my marks. My teacher said that you actually have to use and include the formula linking time to viscosity and directly calculate the viscosity. You can find the uncertainty for the equipment you've used (burette, beaker, stopwatch) either by seeing if it's written onto the equipment itself (it often is), or looking at the uncertainties given in a textbook (I used the Pearson publication with authors Derry, Connor and Jordan). Hope this helps! Reply Link to post Share on other sites More sharing options...
m.k.2015 Posted February 10, 2014 Author Report Share Posted February 10, 2014 I did viscosity for one of my IAs and used time to represent that. I lost the majority of my marks. My teacher said that you actually have to use and include the formula linking time to viscosity and directly calculate the viscosity.You can find the uncertainty for the equipment you've used (burette, beaker, stopwatch) either by seeing if it's written onto the equipment itself (it often is), or looking at the uncertainties given in a textbook (I used the Pearson publication with authors Derry, Connor and Jordan). Hope this helps! What do you mean by connecting viscosity directly to time? Reply Link to post Share on other sites More sharing options...
Guest ryuk1 Posted February 10, 2014 Report Share Posted February 10, 2014 I haven't studied the topic yet so can't help with the labFor uncertainties, our teacher told us to divide the smallest value that the instrument can measure by half to obtain the uncertainty value (at least for analog instruments) Reply Link to post Share on other sites More sharing options...
bluedino Posted February 11, 2014 Report Share Posted February 11, 2014 I decided to investigate how viscosity is affected as the number of Carbons in a homologous series increase. Hence, I just calculated the time taken..Since you said that you're investigating viscosity.. just calculating the time taken will not allow you to get the data to actually investigate viscosity. Viscosity and time taken are two different things. In your method and background information you need to include, explain and use the formula linking time and viscosity - This is a picture of one formula that I've found - notice how you can actually work out a figure for viscosity itself. Hope this makes sense.In case you were interested, I got a 4/6 for my Design on Viscosity without using the formula - I lost both marks in "Developing a Method for Collecting Data" as I only collected data of the time taken, which was not my RQ - to calculate viscosity. 1 Reply Link to post Share on other sites More sharing options...
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