Stoichiometry Project
Evidence of Work
For our first unit in STEM Chemistry we learned about stoichiometry and the basics of chemical reactions as well as balancing equations. The project that was connected with these concepts was a Life-Saving Devices project. We were tasked with using our research and knowledge of these chemistry concepts, primarily stoichiometry, to create a device that would utilize the chemical reaction between sodium bicarbonate and acetic acid to create a "life-saving" device. To the right I included the initial Google document we were given which includes the directions to the project, the preliminary research my group did for the project, and the first outline for our experiments and design for the project.
The device my group decided to create was a phone case that would inflate before it hits the ground. We realized that there was nothing more valuable to people than their phones so the best "life-saving" device would really a product that would protect your phone. Our final design for the prototype was a phone case that included 1 ml bags on each of the corners of the phone, which would hold the sodium bicarbonate. On the back of the phone the acetic acid was located in a closed container which was connected to each of the bags. Once the phone hits a certain speed when falling, the acetic acid is released into the corners and the reaction occurs to create carbon dioxide in hand also filling up the bags. To recognize when the phone was falling we decided to connect our system with an accelerometer app that would deploy the vinegar into bags the critical speed. The picture to the left is the last test we ran to find the perfect sodium bicarbonate to acetic acid ratio we needed. However for our calculations we thought that stoichiometry would provide the most accurate results. Therefore we deduced how much sodium bicarbonate and acetic acid were needed to create the 1 ml of carbon dioxide we wanted to fill the bags.
For this project, our group presented our prototype and calculations through a google slides. The slides we created is attached below. Unfortunately we were not able to create an actual prototype, but we included a design of what our device would look like.
Chemistry Concepts
Stoichiometry: the relationship between the relative quantities of substances taking part in a reaction or forming a compound, typically a ratio of whole integers. To calculate the correct amount of sodium bicarbonate and acetic acid that was necessary for the perfect reaction we desired, we used stoichiometry starting with 1 ml of carbon dioxide. The process for calculating with stoichiometry is very similar to that of unit conversion that would be used in physics.
Chemical Reaction: the process that leads to the chemical transformation of one set of chemical substances to another. For our experiments we tested the chemical reaction between sodium bicarbonate and acetic acid, and analyzed the result. We also wrote down the chemical equation for this reaction which shows both the reactants and the products.
Limiting Reactant: the reactant in a chemical reaction that determines the amount of product that is formed. In the sodium bicarbonate and acetic acid equation, the limiting reactant is the vinegar.
Balanced Equation: an equation for a chemical reaction in which the number of atoms for each element in the reaction and the total charge is the same for both the reactants and the products. To be able to do our calculations with stoichiometry, we needed the correct information from our chemical equation. Luckily enough, the chemical equation is originally balanced for the sodium bicarbonate and acetic acid reaction.
Mole: the standard scientific unit for measuring large quantities of very small entities such as atoms, molecules, or other specified particles. One mole is equal to Avogadro's constant: 6.02214076 × 1023. The unit of moles is necessary for calculations in chemistry and form converting the units of a chemical, for example from grams to particles.
Molar Mass: the mass of a sample of a chemical compound divided by the amount of substance in that sample, measured in moles. In other words, the molar mass is the mass in grams of one mole of a substance. When working through the stoichiometry calculations, we referred to the Periodic Table of Elements to find the molar mass of each chemical compound we were using.
The balanced equation that represents the chemical reaction between sodium bicarbonate and acetic acid is:
NaHCO₃ + HC2H3O2 = CO2 + C2H3NaO2 + H2O
Calculations
Initially, we tried to calculate the amount of carbon dioxide we would create if we used the same ratio of sodium bicarbonate to acetic acid that we found through our experiments. However, we realized that this process was too inaccurate, so we changed to calculating the necessary sodium bicarbonate and acetic acid that would be needed to create 1 ml of carbon dioxide. We worked through our calculations by using stoichiometry to convert units.
Reflection
Initially, my group had a rough introduction to the project and we were not able to brainstorm what our main goal was for the project. However, I was impressed with how quickly this turned around, and the great collaboration that ensued from that point on. The entire group worked very well together and wanted to contribute to the final result of the project. When dividing up tasks and trying to organize how we would work through the project, every individual in the group took an active part in finding a role they could take to contribute to the success of our presentation. After the initial bump our group hit at the start of the project, we had great critical thinking skills. The choice we made for the device we would create was far and away from the basic airbag we were first shown. We put our minds together and thought of an impressive design for a fall-proof phone case that even employed concepts of physics.
Although we had strong group work and critical thinking, we could have improved in other aspects of the NUSD graduate profile 6 C's. As a group I believe that we could have done a better job with our time management as conscientious learners. We spent far too much time running experiments to collect data, instead of moving onto designing our device and running the calculations necessary for the device. In the end, this problem with time management left our group rushing at the end of the time allotted to work on the project. In this project, I took more of a leadership role in the group and was trying to ensure that we finished the project on time. However, my communication skills could have been a lot better throughout the project. I realized afterwards that I did not communicate well enough with our team what specific tasks needed to be done.