 In the chapter on stoichiometry, you will learn that the maximum amount of product is produced when the reactants are in the same ratio as the coefficients in the balanced equation. Many reactions release heat when they occur, and the maximum amount of heat will be released when the reactants are in the same ratio as the coefficients in the balanced equation. In this lab, you are going to react different volumes of a solution of HCl and sodium hydroxide or sulfuric acid in sodium hydroxide, and you're going to determine the mole ratio in which those compounds react. You're going to do this by measuring the change in temperature during the reaction. You will keep the total volume of the solutions that you mix constant, and you will vary the volume of the two reactants. You will measure the change in temperature for several different reaction mixtures and graph the results. You will find the intersection between the data points using the program intersect. The molarity of the solutions are the same, so the volume ratios of the solutions represent the mole ratio of the solutions. We're going to measure the change in temperature using a CBL probe. We're going to use the program heat on your calculator. Start the program, press program on your calculator, arrow down until the program heat is highlighted. Press enter. It's going to tell you it's going to run the program heat, checking to make sure you've turned on the CBL, and that the connections are correct. It's going to ask you how many data points, how many seconds between data points you're going to enter to. It's going to say press enter to start. What we're going to do is put your HCL solution into the cal limiter. Put the probe in the cal limiter, make sure that the tip of the probe is underneath the solution. Press enter on the calculator, wait for two or three data points to be displayed, then add the sodium hydroxide solution. Throw the solution with a probe to make sure there's thorough mixing. As the compounds react, heat is given off and absorbed by the water. The temperature of the solution goes up and is recorded on the calculator. When the CBL says done, press zoom on the calculator and number nine to autoscale to graph your data. Press the trace key and use the arrow keys to get the initial temperature which should be some of the level points at the beginning of the graph, to get the final temperature which should be some of the level points towards the end of the graph. After you've collected all your data and calculated the change in temperature for each of your solutions, graph the change in temperature versus the volume of the acid solution. You should get a set of ascending and descending points. The intersection of the ascending and descending points will give you the maximum change in temperature. This corresponds to the volume ratio and mole ratio of the coefficients in the balanced equation.