Reporting Correct Data

  • Thread starter frozonecom
  • Start date
  • #1
63
0
Significant Figures in Data

Suppose I have two recorded Molarity of a certain solution.
And the data I have are:

0.092 M and 0.095 M --- which both has 2 significant figures.

If I were asked to get the AVERAGE MOLARITY of my substance, then I'd do:

(0.092 M + 0.095 M)/2 = My AVG. MOLARITY.

Since 2 is an exact number, I will not base the SF of my final answer to that number.
Instead, I'd base it to my Molarities, but I know I should do the addition first, since they're enclosed in a parenthesis. (following PEMDAS)

0.092 M + 0.095 M = 0.187 M ----- (It should have 3 decimal places, since that is my least decimal place in my data)

Then, dividing my answer by 2, should I report it as:

0.0935 M ----- since 0.187 has 3 SF
OR
0.094 M ------- since my initial working data only has 2 SF?

Which one is more correct? Which one should I follow and why?
 
Last edited:

Answers and Replies

  • #3
35,143
11,390
I would quote (0.0935 +- 0.0004) M, where the 4 comes from the assumption that both initial values have an uncertainty of 0.0005 each and the remaining part is error propagation.
If you cannot give an explicit uncertainty for some reason, I think I would prefer 0.094 M.
 

Related Threads on Reporting Correct Data

  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
14
Views
4K
  • Last Post
Replies
3
Views
7K
  • Last Post
Replies
4
Views
639
Replies
18
Views
1K
  • Last Post
Replies
15
Views
3K
Replies
2
Views
3K
Replies
7
Views
609
Replies
1
Views
2K
Top