This worksheet is due in class on Thursday at the beginning of class. It will be counted in some as-yet undetermined way toward your course grade. After this worksheet, you should be able to complete PS1a.
Task 1 . Open up the emailed, updated version of Ppt01. It should open up in “Presentation Mode”. Right click on the first slide and choose the “Go to slide ____” option to get to Slide 32 (or you can click through Slides 1-31 if you want to review). Read and click through Slides 32, 33, and 34 and answer the following :
Q1.
a) To use the “multiplication / division” rule for propagating uncertainty in a calculation, you must i) Count up all of the __ significant figures ___s in each given quantity, ii) Identify the number of significant figures (SFs) in the quantity that has the _ few _est SFs. Call this number of SFs “n”. iii) Write down the full answer from your calculator on your paper.* iv) Underline the n th
digit. v) When you reach the final result of your calculation, round the value to the digit that is ____ underlin ___ed.
[*Note: In practice, you need not write down all of the digits from your calculator. Just write one or two more than “n” digits. This is enough to avoid rounding error.] b) Follow all the steps above for:
4.32
45 g
3.12
mL

1.38
60..
.

1.39 g/ mL (for this problem, n = _ 3 _)
For practice with this, as well as writing in scientific notation, see the URL in Slide 35.
Task 2 . Click through Slides 36-38 (spend time analyzing the examples on 38!) and answer the following:
Q2.
a) To use the “addition / subtraction” rule for propagating uncertainty in a calculation, you must i) Determine the ___ decimal __ place of the last significant figure in each given quantity, ii) Of all the decimal places determined in (i), identify the one that is farthest to the _ left __. (Note: the “units” place, “tens place”, etc. are also considered decimal places! I.e., a decimal place need not be a place to the right of the decimal point.) iii) Write down the full answer from your calculator on your paper.* iv) Underline the digit in the ___ decimal place _______ identified in (ii) above. v) When you reach the final result of your calculation, round the value to the digit that is ____ underlin ___ed.
[*Note: In practice, you need not write down all of the digits from your calculator. Just write one or two more than where you will underline. This is enough to avoid rounding error.] b) Follow all the steps above for: 4.3245
g 4.1245
g

0.2000
(You must add the zeros here to “get to” the decimal place identified in step (ii) [see below])
(for this problem, the decimal place identified in step (ii) was the ten-thousandths [or 4 th
] place.)
Task 3.
Click through Slides 39-43, clicking particularly slowly and deliberately on the example on Slide 43!
Then answer the following:
Q3.
a) When a calculation involves both an addition or subtraction AND a multiplication or division, one must i) Do the problem __ step __-wise, writing down each step on one’s paper according to the steps noted in Q1 and/or Q2 above except that (see Slide 41 as well as Rule 4 on p. 24 of Tro for help) : ii) One does not __ round __ the answer to an intermediate step. Rather, one simply leaves the result that has the __ under __line in it on the paper and uses that quantity in the next step. iii) Because there will be underlines in one or more quantities in the second or later steps, one must be very careful to not count any digits past the underline as being _ significant __ figures, or consider any place after the underlined place as being a significant decimal place when applying the Significant Figure Rule to that step .
Read Slide 44 for a review of key points to remember and Slide 45 for comment on online resources.