Mass charge runs Final mass metal strip (g)
Time (s)
Integral value
Run 1
35.94
300
157
Run 2
35.891
302
163
Run 3
35.84
298
149
Run 4
35.79
301
151
Run 5
35.737
300
150
(26pts) Spreadsheet and Graph
When you create your spreadsheet, only plot points where you have collected data.
(15pts)
Upload your spreadsheet.

Export an image of your trendline plot and upload the image here.

(6pts) Analysis
When you enter numbers in scientific notation use the E format. For example:
6.02E23
1.602E-19

(0.5pts)
What is the identity of the metal you used?
(0.5pts)
Enter the slope of your trendline
(0.5pts)
Enter the y-intercept of your trendline
(0.5pts)
Enter the R2 of your trendline
(1pts)
What is your experimental value for Avogadro's number?
(2pts)
What is the percent error in your experimental value?
(1pts)
Based on the following scale (note: this scale only applies to this experiment)

R2 ≥ 0.999 Excellent
R2 ≥ 0.995 Very good
R2 ≥ 0.990 Good
R2 ≥ 0.980 Satisfactory
R2 < 0.980 Questionable!
How would you characterize the "fit" of your data?

Choose...
(4pts) Additional questions
For the first run, you should have recorded the time period for the reaction, the integral of the current, and the mean (average) value for the current. The charge calculated from the product of the mean current × time should be the same as the charge from the integral value (within round-off errors).

(2pts)
a. Calculate the charge based on mean current and time.
(2pts)
b. Does this value agree with the integral? The best way to evaluate this is to calculate the percent difference between the two values. (The percent difference should be small - if it is more than 2%, you probably have made some sort of miscalculation.

(6pts) "What if" type questions
The following are "what if" type questions: If there were some sort of systematic error in your experiment, what effect would that have on your final result (calculated value of Avogadro's Number)? Would your experimental (observed) value be higher, lower, or the same as the value you would have found had everything proceeded correctly. For each of the following, analyze the error and its consequences, and explain your answer clearly. Keep in mind that the "observed" value is calculated with the numbers you collected or otherwise used in the calculations - you complete the calculations without being aware of the problem. In your answer, you must clearly distinguish between the experimental (observed) value and the true value. (Note: The word "it" generally causes problems as in "It will be higher." This may be interpreted as "The experimental value will be higher" or as "The true value will be higher." Be specific!)

(3pts)
a. The balance you used for weighing the metal strip does not zero properly, and consequently, all of your mass measurements are high by precisely 0.050 g (e. g., if you read "20.450 g", the real value was 20.400 g). What effect would this have on your experimental value of Avogadro's Number?

(3pts)
b. The electrical leads from the Constant Current System are damaged slightly, leading to a small "short-circuit" that results in 10% of the measured current passing through the short circuit without going through the metal strips. The current displayed (and hence the value of the integral) are based on the total current, but only 90% of this actually leads to dissolution of metal. What effect would this have on your experimental value of Avogadro's Number? (Note that you complete your calculations assuming that 100% of the current is applied to dissolving the metal strip.)