Framing Statement
In this assignment, we were tasked with writing a lab report for finding the optimum mole ratio of sodium bicarbonate (baking soda) to acetic acid (vinegar). The writing process I have developed that has been the most successful for me is very repetitive, but it gives me the best results in terms of the quality of my essays. In this course I have definitely learned and lived by the idea that writing is a recursive process and creates many drafts. For this lab report I first created an outline which set up the format of the report. I then filled in any information we already knew such as the guiding question or Tables 1 and 2. I then went through and quickly filled in the remaining information needed in order to have everything I wanted to say written down before finally editing for global and then local concerns. These steps are similar to how I approach writing in our ENG 110 course; I begin by putting my thesis at the top of the paper and listing my supporting points, otherwise known as outlining. I then get all my ideas out for each of my supporting points, whether they make sense or not, and finally go through and clarify and connect my ideas.
Optimum Mole Ratio Lab Report
Question: What is the Optimum Mole Ratio for the Reaction of 1.0M Acetic Acid with Sodium Bicarbonate?
Claim: The optimum mole ratio for this reaction should be 1 mole of sodium bicarbonate for every 1 mole of acetic acid.
Evidence: First, we took the mass of sodium bicarbonate measured to the masses displayed in Table 1 below:
SB = sodium bicarbonate, AA = Acetic Acid
Table 1: Determining Possible Optimum Mole Ratios
| Sodium Bicarbonate | Acetic Acid (1.0 M) | Mole Ratio | ||
| moles | mass (g) | volume (mL) | moles | moles SB:AA |
| 0.00500 | 0.420 | 20.0 | 0.020 | 1:4 |
| 0.0100 | 0.840 | 20.0 | 0.020 | 1:2 |
| 0.0200 | 1.68 | 20.0 | 0.020 | 1:1 |
| 0.0400 | 3.36 | 20.0 | 0.020 | 2:1 |
| 0.0800 | 6.72 | 20.0 | 0.0200 | 4:1 |
We then measured 20.0 mL of acetic acid and poured it into a Büchner flask that had a tube connected to it. The tube opens into an inverted graduated cylinder which collects the carbon dioxide created by the reaction in the flask. We recorded the starting volume of air in the graduated cylinder. We then poured the measured amount of sodium bicarbonate into the Büchner flask and immediately plug it with a stopper. The carbon dioxide is collected in the graduated cylinder while we swirl the flask until there are no more bubbles, and the resulting volume is recorded. The flask is cleaned and the process is repeated three times for each possible optimum mole ratio. Our data for the collected carbon dioxide is displayed in Table 2 below:
Table 2: Volume of Carbon Dioxide Collected
| Mole Ratio | |||||
| moles SB:AA | Trial 1 | Trial 2 | Trial 3 | Average | Reactant Remaining |
| 1:4 | 100. mL | 105. mL | 100. mL | 102 mL | relatively very small amount of AA remaining |
| 1:2 | 210. mL | 195. mL | 215 mL | 207 mL | relatively small amount of AA remaining |
| 1:1 | 400. mL | 335. mL | 340. mL | 358 mL | no reactant remaining |
| 2:1 | 440. mL | 450. mL | 445 mL | 445 mL | relatively moderate amount of sodium bicarbonate remaining |
| 4:1 | 455 mL | 445 mL | 440. mL | 447 mL | relatively large amount of sodium bicarbonate remaining |
Justification: The optimum mole ratio is determined by the ratio that yields 1.) the most amount of product and 2.) the least amount of reactant remaining after the reaction is completed. Although the mole ratios of 2:1 and 4:1 yielded more carbon dioxide than the 1:1 mole ratio, at least half of the sodium bicarbonate did not react in those reactions. Additionally, when you balance the chemical equation the mole ratio is 1:1.
NaHCO3 + HC2H3O2 —–> CO2 + H2O + NaC2H3O2
