a Experiment 8 Report .pdf - CHEM 111 u2013 Fall 2020...

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CHEM 111 – Fall 2020 Experiment 8: An Introduction to Acids & Bases Read through the experimental procedure in Chemtrek and watch the associated experiment videos in Canvas. In the provided space, write a lab goal, summarize the procedure, record your observations, and complete all questions included in this report sheet. Upload the completed report sheet to Canvas by 11:59PM the day of your lab. Section A: Common Laboratory Acids and Bases Section B: Indicator Color Probes for Acids & Bases 1 Goal: to explore acids and bases through different techniques such as using indicators, titrations, reactions, concentration, and more. Procedure: Thompson, S. PSU Chemtrek: Expt. 8 Introduction to Acids & Bases; Keiser, J., Hayden-McNeil Publishing. Plymouth, MI, 2020 pp 8-1 to 8-18. In your own words, describe some of what we know about common acids and bases: ( 3 points ) Common acids often require being diluted with water before use. Common bases are also highly corrosive and dangerous in their pure form so they also must be diluted. Most pure bases can dissolve glass so a lot of the time they are packaged in plastic. Both acids and bases need to be diluted very carefully and specifically. Some require being done under a fume hood, and others let off a lot pf heat and require being cooled by an ice bath.
CHEM 111 – Fall 2020 Section C: Acid-Base Titrations; Stoichiometry and Molarity 2 Question 1: In this section you used both a “synthetic” and a “natural” indicator. Which do you think a professional chemist would use? Give at least two reasons to explain your choice. ( 3 points ) A professional chemist would probably use a synthetic indicator, for one since it can convert back and forth between colors making is reversible where as shown above the cabbage pH indicator, a natural on, was not reversible. A synthetic indicator is also a lot more accurate and reliable than a natural one. ( 3 points ) Watch the demonstration video to observe the experiment. In the space below, summarize the experiment and your observations. Is the homemade pH paper reversible? Once the indicator has been switched from one color to another, can it be switched back? The demonstrated had prepared wells that from left to right contained two wells of green BTB and then two wells of red cabbage which was pink. In the two outer most well, (so one of the BTB and on of the red cabbage), the demonstrator added one drop of HCl to each. In the inner two wells NaOH was added. From left to right the colors changed to a yellow orange, then a dark violet blue, a light lime green, and then a brighter pinkish red. The demonstrator made pH paper by using the red cabbage solution and chromatography paper, they tested it with the different solutions, HCl, NaOH, Distilled water and HCl+NaOH from left to right. The color of the paper was originally a light pink color but after adding the different solutions listed above it changed to a darker pink, a lime green, no change other than looking wet, and changed to a darker pink with a green drop on top, from left to right.

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