Day 152

Hi class,

Don't forget to comment below by 8 am tomorrow.

As an optional assignment, you may submit a summary of the lecture on polymers by next Wednesday. The word limit is 500.

On further reflection, the error of the volumetric flask should be used to determine the concentration of the sodium hydroxide solution. The volumetric flask indicates a standard deviation of ± 0.40 mL. In an actual chemistry laboratory class, you would be required to carry that standard deviation throughout your calculation. I'm not going to make you do that. Instead, let's round that error and say the smallest increment on the volumetric flask is 0.1 mL. Therefore, we added 10.00 mL (graduated cylinder) of 1.0 M sodium hydroxide (from stock bottle) to create a 500.00 mL solutions. (1.0 M)(50.00 mL) = M2(500.00 mL); M2 = 0.10 M NaOH. If you've already done your calculations and used a different value for molarity, it shouldn't take much time to redo your calculations. Just go back to your handwritten equations and take everything out to one more digit.

In an actual chemistry lab class, you are required to write in pen during lab, and you cannot rewrite your data onto a new sheet. For this class, you may rewrite your data onto a clean sheet. Here is a link to the Titration Lab Packet. You do not need to attach your calculations on a separate sheet. The sample calculations in the report are sufficient.

I wish I had time to give a tutorial on Excel since this program is used frequently in chemistry. I recommend using Excel whenever possible. If one of your measurements is incorrect, you can simply replace that number rather than redoing every calculation.

I require at least two citations on this lab report. I forgot to mention that you can also cite further experimentation in your conclusion section. Here is a link to the ACS Citations. Most of the articles on Google Scholar are inaccessible to the general public, so you may use other sources (not Wikipedia). I found several sources that describe how phenolphthalein works, so you shouldn't have any issues finding these same sources.

Email me if you have any questions.