[(exp value - accepted value)/accepted value]*100 = percent error.
For exp value, do I have to average my five trials?
Yes I think you do. You add them together and then divide by how many trials you had. Then use that value to plug into the exp value.
Personally, I would calculate the percent error of each trial, then do the averaging bit. You want to know the error of each sample you did AND you wnt to know the average. To calculate percent error ONLY on the average doesn't tell you anything about how accurate each titration was. But when all is said and done, you want the average percent error, too.
Percentage difference is the same as percentage error?
yes
Assuming, of course, that the difference we are measuring is the accepted value. But you can find the average results, then find the percent difference between the average and any one of the trials.
To calculate the percent error, you need to compare the experimental value to the accepted value. The formula you provided is correct:
Percent Error = [(Experimental Value - Accepted Value) / Accepted Value] * 100
Regarding your question about averaging your five trials, it depends on the specific context of your experiment.
If your five trials represent multiple measurements of the same quantity under the same conditions, then yes, you would typically calculate the average of these trial values to obtain a 'representative' experimental value. This average experimental value would then be used in the percent error formula.
On the other hand, if your five trials were conducted to measure different quantities or were done under different conditions, you may not need to average them. In such cases, you would calculate the percent error individually for each trial by substituting the trial value as the experimental value in the formula.
In summary, if your five trials correspond to multiple measurements of the same quantity, averaging them is appropriate. If not, you can calculate the percent error for each trial separately without averaging.