CHEM 2204

Chemical Laboratory Techniques

Browsing Posts in Past Labs

Lab 3 Site Data

No comments

Please check the data for your set.

Set A site data
Set B site data

Using the built-in functions of your SHARP calculator, determine:

  1. Mean or Average, x
  2. Standard deviation, sx
  3. Relative standard deviation, RSD = (sx /x)· 100

for the following set of data: 95, 80, 80, 75, 75, 75, 50

Screen Display
Put calculator in statistic mode 0.
Input 95
(95 M+)
1.
Input 80 two times
(80 M+)
2.

(M+)
3.
Input a number, 75, three times
(75 STO 3 M+)
4.
Input a number, 50, once
(50 M+)
5.
Screen Display
To display Mean
(RCL 4)
75.71428571
To display Standard Deviation
(RCL 5)
13.3630621
To display Relative Standard Deviation
(RCL 5 / RCL 4 * 100)
17.6493273

Therefore, for our data, we can write 75.7 ± 13.4 or 75.7 ± 17.6%

Question: “What should I do if I entered (and stored) a wrong data point on my calculator ? I don’t want to re-enter everything!”
Solution (How to correct after realizing one has stored an incorrect value):
(Courtesy of Vicky Tsui, CENV graduate)

  1. Continue entering the rest of the data points
  2. After that’s done, scroll up with the “up arrow” on the calculator to find the incorrect data value
    • The calculator will scroll through a series of “X=” and the corresponding “N=” entries (i.e. X1=___, N1=___, X2=___, N2=___, etc.)
    • The “X=” fields represent the data points entered, while “N=” denotes the frequency of the corresponding data value (X)
      (for the purpose of the lab, N would equal 1 (default)…. unless if you want to specify the N number of times that a value is repeated)
  3. Once the calculator is displaying the incorrect value, “X= ____” , input the desired correction value and press “M+” to store this number in its place

DONE 😀 (proceed to find the mean, SD, etc.)

To clear data set

Start over!

Read the following:

  1. T & P 3 – Volumetric flask, Pipette, Standard solution, Dilution, Graphing
  2. Demonstrations of Nine Practical Lab Techniques – Techniques 2, 3, and 7. Read through the lab carefully before coming to the lab.
  3. Read Friday’s schedule.

Prior to coming to the lab, read the lab and do the prelab calculations so that you can maximize practice time. Fill in the highlighted fields on page TP3-8, TP3-9, and TP3-11.

Remember to bring Lab 2 datasheets as we will be weighing the crucible from last week.