Error Analysis

Formulas:

Calculations for Pie Charts:

Note: Pie charts may be neatly hand drawn or put together on the computer and printed. They should be in color (unless printed). Pie charts will not recieve most of the credit if calculations are not included.

To find each piece of the pie chart you must find the first total sample. Please note that this must be only the sample weight and must not include the mass of the container. You must subtract out the weight of the container if your original weight also includes the container (this will throw your pie chart calculations off!).

If you have your total sample weight:

Use the % by Weight Formula above to calculate each piece.

Example: if your sample weighed a total of 30.21 grams and 1.50 grams of it is sodium chloride (NaCl) you would set up the problem like this:

= 4.96 % Sodium Chloride

This would equal one slice of the pie chart that represents sodium. Since it is only 4.96% it will be a very small piece of the chart. When you turn in a pie chart it should contain five things:

• Pie Chart
• Calculations to get each of the components (this is most of the credit)
• %'s labeled for each wedge AND type of component (eg: "sodium chloride" = 4.96% pointing to the wedge that represents this amount)
• % Error Analysis (% Error) - include this AFTER you finish your calculations & make your chart (see below for help)
• Error Analysis Reflection (see below for help)

To calculate % Error use the top formula.

Your total sample weight (without the mass of the container!) = theoretical Value

Add all of the masses that you found together = experimental value

Put into the equation (make sure you multiply by 100 at the end) and that is the percent your experiment is off by.

Writing a Reflection (be specific and explain EVERYTHING)

It is important to recognize all possible sources of error. This includes possible problems with your data numbers (be specific, which ones and why for credit), human error (things that went wrong in the lab, or troubles you had with the experiment). This should be a reflection on EVERY aspect of what you did.

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