The differences between titration of strong acid and weak acidIntroduction: This experiment aims to explore some properties of strong acid (HCl) and weak acid (HCOOH) and how these properties affect titrations. The first is to find out the properties and differences of strong acid using phenolphthalein measurement and curve measurement. The second step is to find out the properties and differences of the weak acid using the measurement and curve of phenolphthalein. The final step is to compare the salts produced. For both acid-base titrations, the basic mechanisms are the same. The general procedure is to add 3-4 drops of phenolphthalein before adding NaOH into the acids. Then start adding NaOH until the pH indicator turns pink and continue to continuously record the volume of NaOH added. The choice of pH indicator is very important in this experiment because it determines the experimental equivalence point and whether or not to move on to the next steps. Phenolphthalein is an appropriate indicator because the solution will change from acidic to basic and phenolphthalein will have a pink color between 8.2 and 9.8. (McMurry. Fay. 2012)For the titration of HCl and NaOH, we start with 50 mL of HCl (0.05 M). Before titration add 3-4 phenolphthalein into the HCl solution and adjust the pH meter and burette. Add approximately 4 ml of NaOH each time until the pH is approximately 2.5. Then change the addition of NaOH to 0.2 ml or less each time until the solution turns pale pink and persists for a few seconds. Then continue adding 0.2 ml until there is a noticeable change in the pH value. Next, make four 0.4ml additions and continue adding a large amount of NaOH until the base is consumed approximately 15-20 after pale pink. For the titration of HCOOH and NaOH,...... half the paper..... .n more than expected. Third, the indicator also causes small errors because it is not neutral, but is weakly basic, so the original solution may be less acidic than we expected. Last but not least, the pH meter may not be accurate. For example, after calibrating the pH meter and discarding the buffer, the pH changes slightly (6.98). Therefore, any data collected subsequently may be slightly lower than the actual value. Conclusion: The properties of the acid and base determine the pH of a salt. The basic salt has an equivalence point higher than 7 (pH(HCOONa)=8.6) Neutral solution The acidic salt associates lower than 7 (pH (NH4Cl)=6.45). And the neutral salt like NaCl has the point equivalent to 7.Bibliography:JEMcMurry. RCFay. Chemistry. 6E. Pearson Prentice Hall. 2012Laboratory Manual for Chemistry 139. Department of Chemistry, University of Toronto. Winter 2015