Question

I have this lab for Quantitative Analysis that is worded a little strangely. I was hoping someone could explain what is meant by plotting average measured volume by expected volume delivered. How can one average be plotted against another average?

Prompt: Convert the mass of water to the volume delivered by the pipette. Plot the average measured volume obtained from your replicate measurements delivered versus the expected volume delivered as read on the pipette for the 10 mL pipette. Plot y-value error bars corresponding to the standard deviation obtained from your replicate measurements.  

Answer 1

DEAR STUDENT, AS YOU WOULD BE AWARE THAT PIPETTE IS USED TO TRANSFER A MEASURED VOLUME OF LIQUID. HOWEVER, DUE TO EXPERIMENTAL ERRORS WHICH MAY INVOLVE TAKING INCORRECT READING IN PIPETTE, ANY UNFORESEEN MISTAKE IN TRANFERRING THE LIQUID, DESIRED VOLUME OF LIQUID IS NOT TRANSFERRED. THEREFORE, PROMPT STATED MEANS THAT MASS OF WATER DELIVERED FROM PIPETTE IS MEASURED SEPARATELY FOR EACH DATA SET & IT IS CONVERTED TO VOLUME BY USING DENSITY OF WATER. THIS VOLUME HAS BEEN CALLED MEASURED VOLUME & IT MAY DIFFER FROM THE VALUE OF VOLUME OBTAINED FROM PIPETTE READING(THIS VOLUME HAS BEEN CALLED EXPECTED VOLUME). YOU SIMPLY HAVE TO PLOT THESE TWO VOLUMES FOR EACH MEASUREMENT ON A GRAPH.

FOR EXAPMPLE, YOU TRANSFERRED 5 ML WATER AS PER RPIPETTE READING. EXPECTED VOLUME IS 5ml. NOW, MASS OF THIS VOLUME TRANFERRED IS CALCULATED. SUPPOSE IT COMES OUT TO BE 4.9 GRAM. IF WATER DENSITY FOR EXPERIMENT IS 1gram/ml, THEN VOLUME OBTAINED FROM MEASURED MASS IS 4.9 ml. THIS IS MEASURED VOLUME. THESE TWO VOLUMES HAVE TO BE PLOTTED WITH OTHER SUCH SET OF READINGS.

NOTE: DEAR STUDENT, I HOPE I MAY HAVE SOLVED YOUR QUERY. KINDLY INFORM ME. THANK YOU.