Lab Report

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Background/Introduction:
The purpose of the experiment is to determine the ID of an unknown diprotic acid by establishing its pKa values. The first phase is to determine the unknown diprotic acid by titration, which is a technique where a solution of known concentration is used to determine the molecular weight. While the second phase involved seeing how much NaOH needed to standardize diprotic acid.
Brønsted and Lowry’s concept of acids and bases detail that these reactions are basically proton transfer reactions. Acids act as proton donors, meaning that they give away a hydrogen ion. While bases act as a proton acceptors, entailing that they receive a hydrogen ion. During reactions between acids and bases, acids are paired with hydrogen, while bases are paired with a hydroxide group. When these two react in an aqueous solution and a salt is produced, that lacks both acidic and basic properties, and water is produced. Then neutralization has occurred. Neutralization occurs when a strong acid and a strong base react, because they completely dissociate in water.
Polyprotic acids are acids that are capable of donating more than one proton per molecule in acid-base reactions, hence the prefix poly- meaning many, and prot- referring to protons. Polyprotic acids are acids that have more than one ionizable hydrogen atom per molecule. When acids are added to the solution, the acid ionizes. When the acid partially ionizes in solution that means it is a weak acid. Weak acids partially dissociate to produce equilibrium concentration. K_a is the acid ionization constant that refers to when an acid donates a proton. We determine
K_a = ([H_3 O][A^-])/([HX]) pH measures how acidic or basic something is. pH is the measure of the concentratio...

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...nt were quite successful. There were only a couple of mistakes that were committed including over titrating in phase 1 and inaccurate measurements of many substances. However, our results did not differ that much from the actual value and phase 2 went very successfully because we found the amount of NaOH needed to standardize the acid. Overall, I would consider this lab a success because we found the molarity, the amount of moles, the pKa, the ka, the equivalence points, and the molecular weight that did not differ that much from maleic acid. Maybe next time, we could make sure none of our equipment were contaminated and we could take our time with phase 1 of the experiment. Our percent error was just above 5 %, probably due to the fact of the contaminations and inaccurate measurements that were partaken in.
Citation:
Vernier, S.O.P., pg. 25-1 – 25-10; method 1 only

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