Ours landed 10 — 20 feet from where they were launched. Count how many seconds it takes for one to pop. Try adjusting variables such as using just one quarter tablet and three quarter tablets, using a little water or a lot, or shaking vs. Learn more about this method. Pack it into the inside of a film canister lid. Fill the canister halfway with vinegar. Put the cap on. Flip it over and step back.
Note: in this video, the set up is done by 30 seconds… the launch is at if you want to skip ahead to the excitement. Take film canisters.
Fill them about halfway with a water-based paint we used 1 part tempera mixed with 2 parts water. Add half of an alka-seltzer tablet. Quickly seal. Shake a bit. Set down upside down on a piece of paper. Quickly move away! Note: this could make a very big mess.
We did this one as a teacher demo, not hands-on for the kids. Prep : Glue a half an alka-seltzer to the inside of each lid. Put paper down on the floor. Line up the prepared paint canisters on the paper, with their lids next to them, and a big plastic tub next to that.
Show time : Put all the lids on. Turn all the containers over, shaking if desired, then put them lid down on the paper. Put a tub over them. Expect about 25 seconds to first pop. Pack the paste inside the lid of a film canister. Then fill the canister a quarter of the way with vinegar and flip it over.
In the video, we used a half canister of vinegar, and that was too wet. You could use a test tube with a stopper or a glass bottle with a tight-fitting cork.
Test to see what quantity you need to pop the cork. Start with small quantities, and work your way up. You are working with projectiles here, and the timing is unpredictable. Start with a little bit of reactant e. Model for the children how to work carefully and step back out of the way of the launch.
This can be anything, but try to seek answers with specific regard to the variables being changed in this activity. At the end, collect and present all class data on the board. Highlight discrepancies and the general trend.
You must be logged in to post a comment. Skip to content. June 19, June 23, Sid M. Fill the beaker with water up to the mL mark with cold water and stir the ice water until the temperature equilibrates. Measure the temperature of the water and record it in the table. Add a tablet and record the time it takes for the tablet to react. Repeat with room temperature water, then with hot water heated to 70 degrees C using a hot plate. The Effect of Surface Area on Rate of Reaction Prepare three different sizes of the Alka Seltzer tablets: A whole tablet A tablet broken into quarters A tablet ground into powder: Place the tablet it a piece of weighing paper wax or parchment paper work as well and break it either with your hands or crush it using the back of a metal spoon.
Most reactions proceed faster as the temperature increases. Is the same true for dropping an Alka-Seltzer tablet into water? Indeed it is!! Depending on the temperature of the water, the tablet will stay on the bottom of the container until the reaction is finished very cold water , or float on top of the water through-out the entire reaction warm water. At a temperature in between the two extremes, the tablet will start off on the bottom of the container, then as its mass decreases, gradually move to the surface of the water.
Crushing the tablet into a fine powder can also be used to illustrate the effect of surface area on the rate of a reaction. A much safer although not as spectacular demonstration than blowing flour into a Bunsen Burner flame!! Some students may initially expect that exothermic reactions should proceed much faster than endothermic reactions, but this is clearly not the case. The exothermic conversion of gasoline to the combustion products CO 2 and H 2 O is extremely rapid, but the reaction takes place only after the gasoline has been ignited.
We can classify gasoline as being thermodynamically unstable relative to the products of combustion exothermic process , but kinetically stable reaction is very slow in the absence of a spark. The rate at which a reaction takes place is a function of the height of the energy barrier between reactant and product. This barrier is known as the activation energy E a and the reactant molecules must collide with sufficient energy and the correct orientation with respect to each other to surpass the barrier.
Increasing the concentration of the reactants will result in a greater number of collisions and therefore a faster rate of reaction. Raising the temperature will also lead to a greater number of collisions and therefore a faster rate of reaction. The rate of any reaction involving a substance X can be written as:. In the reaction of the Alka-Seltzer tablet with water, one can make the assumption that the rate of the reaction is first-order. The rate of the reaction can be measured by observing the time t x taken for the Alka-Seltzer tablet to disappear.
The relationship between the rate constant k and the activation energy E a is as follows:. The students should realize that this equation is in the form of the general expression for a straight line, i. Place mL of distilled water in a mL Erlenmeyer flask and determine the temperature of the water.
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