Exp.14 Pt.1 done.docx - Penn State CHEM 113 Experiment 14...

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Penn State CHEM 113 Experiment 14 Part 1: Acid-Base Equilibria Read through the experimental procedure in Chemtrek and watch the associated experiment videos in Canvas. In the provided spaces, write a lab goal, summarize the procedure, record your observations, and complete all questions included in this report sheet. Experiment Goal. Complete before lab. Be able to interpret conductivity experiments, investigate acid-base equilibria from bromocresol green, determine acid dissociation equilibrium constants, use a universal indicator as a color probe to sense pH and investigate various quantitative features of acid-base chem through titration curves. Procedure: Thompson, S. PSU Chemtrek: Expt. 14 Acid Base Equilibria; Keiser, J., Hayden-McNeil Publishing: Plymouth, MI, 2020, pp 14-1 to 14-39. Section A. Conductimetry and the Strength of Acids and Bases Pre-lab data collection and observations. Complete before lab. Using a clean conductivity probe, 6 liquid solutions are tested. Between each the leads is rinsed with distilled water. Record whether each solution got a reading, if yes, at what level out of 10? Table 1: conductivity of various solutions Solution: Distilled water Tap water CH 3 COOH 0.1M NH 3 / NH 4 OH 0.1M NaOH 0.1M HCl 0.1M Reading: N/A 5 / 10 4 / 10 5 / 10 8 / 10 9 / 10 Question 1: Arrange the six solutions tested from the lowest to the highest conductivity. Explain the order observed —i.e., why do solutions of the same concentration have different conductivities? If you cannot differentiate between them, explain why not. DI < acetic acid < tap = ammonia/ammonium < sodium hydroxide < hydrochloric acid. Conductivity of a solution is dependent on the amount of charge carriers/ions a solution has. Each of these solutions tested have different amounts of ions (except distilled water) despite being the same concentration. Question 2: The conductivity of an H 2 SO 4 solution was followed as it was titrated with the strong base Ba(OH) 2 . Predict the relative conductivities of: H 2 SO 4 + Ba(OH) 2 BaSO 4 + 2H 2 O (a) the starting solution Will be more acidic and have removable ions. Meaning it will be conductive. (b) the solution at the equivalence point The acidic will be completely reacted with the base at the equivalence point, creating water and an insoluble salt. Water will not consist of ions, so will not be conductive.

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