The purpose of this lab should consist of several well constructed sentences stating what the experiment was designed to accomplish. Make sure to include statements about concepts and techniques explored in the experiments. The procedure section should reference the lab manual and include any changes made to the lab manual procedure during the lab.

The data section should include three tables. The first table should be for the acid and include the following information: a) concentration of acid after each dilution, b) experimental pH of each dilution, c) theoretical pH of each dilution, and d) percent error in the pH value.  The second table should be for the base and include the following information: a) concentration of base after each dilution, b) experimental pH of each dilution, c) theoretical pH of each dilution, and d) percent error in the pH value. The third table is for the combined acid and base solutions and should include: a) Concentration of acid and base for each combination, b) experimentally determined pH, c) the theoretical pH (HINT: Think DI water) and d) the percent error in the pH value.  Also make sure to include the pH of the DI water used for the dilution. Finally state the balanced chemical equation for this experiment, the theoretical and experimental yield of the salt obtained from heating the acid/base mixture and percent yield of the reaction.

The majority of the information listed above was either determined in the pre-lab exercises or during lab. The concentration of acid or base can be determined using the balance chemical equation, since the reaction is 1:1 the following formula can be used:

M1V1 = M2V2    

(M1 is the concentration of the new solution, M2 is the concentration of the solution you already have made, V1 is the volume you want to make which in this case will always be 25mL, V2 is the volume of the already made solution that you use which for all these dilution is 1mL, therefore solve for M1)

The experimental pH is determined in lab but the theoretical pH can be determined for the acid by using pH= -log [H+], the [H+] is the hydrogen ion concentration which is equal to the concentration of acid you calculated in part a.  For the pH of the base you must first determine the pOH, using pOH= -log [OH-], where [OH-] is the concentration of the base you determined in part a. Once you have determined the pOH you need to subtract it from 14 to obtain the pH. (pH=14 - pOH). The experimental error can be determined with the following formula:

            % error = Theoretical Value – Experimental Value               x     100%
                                           Theoretical Value

Using the balanced chemical equation to determine the theoretical yield of the salt produced. To do this you will need to determine the moles of acid or base (pick one) used in the mixture you heated based on the Molarity of the solution and the volume of the acid or base you used (M= moles/L). Do not combined the acid and base together. Using your balanced chemical equation, the stochiometric ratio, and the moles you just determined to determine the moles of salt produced. In other words go from moles of Aà moles of B. Finally convert the moles to grams and use the percent yield formula below to determine the percent yield.

% yield =        Experimental Yield (g)        x   100%
                        Theoretical Yield (g)

In the calculation section be sure to include examples calculation for the following: a) concentration of dilution b) pH, c) pH from pOH, d) experimental error, e) theoretical yield of salt, and f) percent yield of salt. Also include Excel graphs of the pH vs concentration for both the acid and base. Remember all graphing guidelines apply here.

The conclusion section should be several paragraphs in length and include the following information: a discussion on the experimental and theoretical pH as well as the percent error for both the acid and the base, be sure to discuss in detail any discrepancies in the values. Within this discussion explain the trends seen in the graphs you made.  A discussion on the pH of the combined solutions and the error in the values: be sure to include a statement about what is expected from these mixtures, and why that was not achieved. Finally discuss the percent yield of salt and any errors which may have caused a yield less than or greater than a hundred percent.

Answer the following questions:

1) Explain how this experiment can be related to limiting and excess reagent problems.

2) The acid and base used in this experiment are monoprotic. How would the experimental results vary if a diprotic acid had been used instead?