chemical dominoes
For this project we had to make basically a Rube Goldberg machine, but using chemistry. We needed to make a multi-step process to do some task at the end of the system, but make the system run off of some chemical reactions.
We decided to make a light bulb light up at the end of our system. We created a circuit that prevents the bulb from lighting up when two ends are attached to an aluminum piece. There is a reaction that can alter the aluminum piece and break the circuit. To pour the solution onto the aluminum to break the circuit, we made another reaction to fill a balloon with gas to push several levers which help pour this solution. There are also two middle reactions that can be seen between the balloon and aluminum circuit reactions. The first creates a visual change between two solutions and another lights a medium size fire.
We decided to make a light bulb light up at the end of our system. We created a circuit that prevents the bulb from lighting up when two ends are attached to an aluminum piece. There is a reaction that can alter the aluminum piece and break the circuit. To pour the solution onto the aluminum to break the circuit, we made another reaction to fill a balloon with gas to push several levers which help pour this solution. There are also two middle reactions that can be seen between the balloon and aluminum circuit reactions. The first creates a visual change between two solutions and another lights a medium size fire.
The chemistry with some physics
Step 1: Balloon Expansion
The goal here is to fill up a balloon with gas when these two substances mix. Vinegar and baking soda produce a gas when combined and that gas fills up the balloon which begins the next step. Step 2: What just happened? This step is both chemistry and physics. We liked this reaction because it creates a yellow pigment from two completely clear substances and it acts as a catalyst for the next steps. As the balloon tilts up the lever above it, it pours down lead nitrate into potassium iodide which react with each other. Step 3: Fire! We had one cup with a small amount of alcohol on fire and then a bucket of soap bubbles. As the mass change from step 2 pushes the levers, it drops the fire into the bubble vat and creates a decent sized flame for a short period of time. Step 4: The Light Our final step of the chemical dominoes takes a bit of time. One solution gets tilted onto aluminum and eventually breaks the aluminum, which then completes the circuit and turns the LED light on. |
Step 1 Chemistry:
Vinegar is diluted acetic acid(CH3COOH) and baking soda is sodium bicarbonate(NaHCO3). When combined, they undergo two reactions. The first is a double displacement reaction, a reaction where two elements of two products switch in the reaction, which produces sodium acetate(CH3COONa) and carbonic acid(H2CO3). Reaction 1 Equation: NaHCO3 + CH3COOH --> CH3COONa + H2CO3 Then the second reaction occurs. This one is a decomposition of the unstable carbonic acid. The carbonic acid breaks down into carbon dioxide and water. The carbon dioxide then inflates the balloon. Reaction 2 Equation: H2CO3 --> H2O + CO2 Step 2 Chemistry + Physics: Lead nitrate[2Pb(NO3)2] combine in a double displacement reaction with potassium iodide(KI) to create a solid pigment and another substance. The pigment created is lead iodide and that is what makes the yellow color. Reaction Equation: 2Pb(NO3)2 + KI --> 2PbI2 + K(NO3)2 The physics part of this step is that the change in mass on cup that contains both solutions creates a larger force on it's part of the lever and moves the levers connected to it. Step 3 Chemistry: The bubbles are made from diluted dish soap. Since the bubbles contain a small membrane of dish soap, they are able to be caught on fire. The fire then spreads out to the rest of the bubbles until all of them have been popped and burned. Step 4 Chemistry: The solution poured onto the aluminum was copper chloride[Cu(Cl)2]. The two underwent a single displacement reaction, which created copper to break the aluminum, and aluminum chloride as a liquid. Reaction Equation: Cu(Cl)2 + Al --> Al(Cl)2 + Cu |
reflection
This project went very well. It was just like going into freshman year and recreating the Rube Goldberg project, but just with some added chemistry. Our group very quickly developed our ideas and went right to work. We did have some trouble with always staying on task. Some individuals got sidetracked and then just started to chat with classmates. We also had trouble generally making good use of our time for the project. At the same time I believe our group developed an idea that wasn't too ambitious so that we would be able to get it done on time. We also efficiently tested our project so that it did not take very many trials to perfect it for the final go. All in all this was a fun project that went very well.