5.1 Rates of Reaction

Ok, so the last experiment that we did really focused in on the reasons that a reaction will proceed at a certain rate. The way that you will need to think about this process has to do with particle collisions and how they influence how fast the reaction will happen. For a reaction to happen we need what is called an effective collision. This means that the particles have collided in such a way that there will be a chemical reaction. The changes we made in the lab, influence the number of effective collisions that were occuring.

The first thing that we did in the lab was try to make a plan so that you could determine how the lab would be done so that you could tell how changing each variable would influence what happened. Describe quickly what you did in the experiment. Include in this description why it was important that you controlled the variables in a certain manner. Why was your procedure effective at determining how each variable influence on the rate? What would happen if you changed multiple variables at the the same time?

By changing the concentration of the vinegar, the temperature of the vinegar, and the amount that the tablet was crushed the rate of reaction was changed. Describe, using particle collisions why each variable changed the rate. Also describe if the results in your experiment were consistent with what you expected to happen. If they aren't, describe something that could have gone wrong in the process.

Enrichment: Do some online research and find an example of a real-life catalyst. Find out what changes in the reaction and how that has a significant influence on the rate of reaction. If you need help getting started catalysts are often used in industrial processes in order to make reactions more efficient. Also, you could look at enzymes and see specifically how they change a biological process.

Lab 4.2 Heating and Cooling Curves of Lauric Acid

Now that you have had the chance to digest the heating and cooling curve process a little bit, I am going to ask you guys to think about what happened in the process. Here are two graphs produced from Jake Eggleston and Nate Gillian's data.






Paragraph #1: Take a look at the graph that you made as a result of the data that you collected. Identify the melting point of lauric acid from the above graph. Identify the freezing point from the second graph that you made [many of you put the on the same axis, which is fine]. Are these two values the same (and should they be the same)? Explain how you determined the freezing and melting points from your data.

Paragraph #2: As you heat a substance to its melting point and through the phase change there are changes that occur in both kinetic and potential energy. Explain what kinetic energy is and when it is increasing during your heating curve and decreasing in your cooling curve. Explain what potential energy is, and also explain when it is increasing and decreasing in your curves.

Enrichment:

Lauric acid of course has an actual melting point. Find the actual melting point and compare it to your data. Calculate the percent error and predict a reason why you were high or low (the thermometers are accurate, so don't blame them.)

Find out more about lauric acid. Maybe what it is used for, or could potentially be used for, find its chemical formula, structure, anything relevant about the chemical. Reference the source that you used to find the information.