The Extra Digit

Today in lab I had one guy come up to me with his paper and I knew that he had a problem. You can always tell on their faces when they are angry/disgusted.

"Hey, I know that NaOH is a strong base, but the number it is returning according to her chart (I assume he's referring to Dr. Potts. He seems to be pretty bitter ever since she kicked him out of lab for coming 11 minutes late.) this value would show me that it was a weak base."

I assume that he's had it up to here with not getting the required results on his lab report and I can sympathize. Dad once told me that the best thing to do was work backwards: figure out the theoretical answer first and make up "real-life" measurements to match. (When I told two girls that acetic acid was a weak acid not a strong acid and couldn't have a value of 4963, they made up a value: 1234. How obvious was that?)

So I looked at it prepared to tell him that the Verniers were new so we weren't sure they all worked and sometimes the beakers had residue, blah blah blah, etc. However I was shocked to see his value was approximately 24000. He had been reading it as 2400 since the break-off point was 2500 and he naturally assumed that all the values would be within 50 of the break-off point. In reality all the strong acids have five digits and the weak acids have four. Pretty obvious. Anyway I pointed this out and was satisfied to see all his rage against the machine was away. He didn't have any more questions after that. Hooray for learning experiences!