Demonstration of Composition Changes in a Distillation Column by Use of Bromophenol Blue Indicator

Evjen, Sigvart; Petit, Coralie; Hammer, Mikael; Lindbråthen, Arne; Flatberg, Gøril; Karolius, Sigve; Presig, Heinz; Fiksdahl, Anne

doi:10.1021/acs.jchemed.8b00736

Cited by 3 publications

(4 citation statements)

References 5 publications

(6 reference statements)

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“…This enables students to visually follow the solubility change and partition between the two immiscible layers after shaking the separatory funnel. Dyes have been widely used to illustrate a variety of chemical properties and concepts such as solubility, acid–base chemistry, chromatographic separation, distillation, and LLE. ,,,− ,− In previous work describing laboratory experiments on LLE, authors employed these colored compounds as a visual aid to help students determine the partitioning of molecules into different layers as a function of pH. Sudan Blue and Congo Red, or Nile Blue and 2,6-dichloroindophenol, are among the most common dyes utilized for this purpose.…”

Section: Discussionmentioning

confidence: 99%

Visually Tracking Acid–Base Extractions Using Colorful Compounds

2020

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Acid–base extraction is an important concept in organic chemistry that beginning students often find challenging to comprehend. Herein, we describe the use of a simple demonstration suitable for lecture that allows students to visually track the chemical events that take place in a separatory funnel. The demonstration involves the use of two safe and available dyes with different acid–base properties, phenolphthalein and neutral red. The dyes present distinct colors in their ionic and nonionic forms. With a change in the pH of the media in the separatory funnel, the colors of the solutions change according to the compounds’ ionic states and their solubilities in either the aqueous or the organic layers. This provides a visual record of chemical concepts, which helps students to better understand the partition of different molecules between the organic and aqueous layers in an extraction process. In addition, we provide resources describing how to use this demonstration in class aiming to enhance students’ engagement and comprehension of the topic.

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Section: Discussionmentioning

confidence: 99%

Visually Tracking Acid–Base Extractions Using Colorful Compounds

2020

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Section: ■ Experimental Designmentioning

confidence: 99%

“…A critical design feature of this guided-based experiment was the use of colorful dye compounds that would permit students to track the solubilities of their dyes in the aqueous and organic layers. The employment of colored compounds has been an effective approach for demonstrations and laboratory exercises on separation techniques such as thin layer and column chromatography, − distillation, and LLE. ,− The utilization of a colorful approach to teaching LLE has been recently reported as an effective method for students to connect the concepts of molecular structure, acid/base chemistry, and partition equilibria to the LLE technique. − A few examples have employed a guided inquiry-based methodology, − although all of these procedures direct students toward the same outcome for the entire student body. The goal of this experiment was to utilize a colorful approach for teaching LLE with the implementation of multiple outcomes to ensure that the entire student cohort can reap the full benefits of inquiry-based learning.…”

Section: Experimental Designmentioning

confidence: 99%

A Multioutcome, Guided Inquiry-Based Liquid–Liquid Extraction Laboratory for Introductory Organic Chemistry

Luska

2022

J. Chem. Educ.

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A multioutcome, guided inquiry-based liquid–liquid extraction (LLE) experiment has been designed for introductory organic chemistry. Multiple outcomes were established by identifying a series of red and blue dyes that are (1) soluble in organic solvent, (2) soluble in aqueous solution, or (3) soluble in either the organic or aqueous layers by tuning the pH of the aqueous solution. This series of dyes led to the development of 10 different dye mixtures that can be separated using LLE. In this experiment, students first evaluate the individual solubilities of three assigned dyes under neutral, acidic, and basic biphasic conditions. The colored nature of these dyes allows students to visually follow their solubilities and thus make connections between solubility and the molecular structure, ionization, and acid/base properties of these compounds. Then, students develop a two-step LLE procedure to separate a three-component mixture of their dyes using the observations from their solubility study, and they perform their separation to verify its effectiveness. Student feedback has shown that the visual nature of this lab permitted >90% of students to prepare a successful separation procedure and that students left this lab feeling more confident about LLE. Further, students felt that this guided inquiry-based experiment allowed them to develop laboratory skills, while also improving their understanding of LLE, enhancing their problem-solving and critical thinking abilities, and increasing their engagement and enjoyment in the lab. The ability to diversify the inquiry problem ensures that all students performing this experiment gain the full benefits of conducting inquiry-based learning.

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“…Hydrolysis of calcium carbide to liberate the flammable acetylene gas has been reported in different contexts. − Herein formation of the visually attractive acetylene–air flame by hydrolysis of calcium carbide to rid blind beliefs and misconceptions regarding the purported water lit lamp has been demonstrated. Many such demonstrations and activities underlying chemistry principles have been hitherto studied to enthuse students in the subject. − From ancient times alchemists and magicians have been using chemistry principles pseudoscientifically in their ventures . Chemistry has enthralling tenets and magnificent applications that have immensely benefited mankind, but some of its visual manifestations being covert to decipher for the layperson are many a times perniciously exploited by some.…”

Section: Introductionmentioning

confidence: 99%

Demonstration of Acetylene–Air Flame by Hydrolysis of Calcium Carbide to Rid Blind Beliefs and Misconceptions Regarding Purported Water Lit Lamp

Borkar

2023

J. Chem. Educ.

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The simple demonstration presented, herein, involves the combustion of acetylene liberated from the rapid hydrolysis of 0.50 g of calcium carbide. The unsaturated hydrocarbon formed burns with a yellow sooty flame in air. This acetylene-air flame being visually attractive is often misused by those attempting to showcase their illusory magical prowess by feigning to light a lamp on water. The present enlightening demonstration enables the understanding of the chemistry principles underlying the purported water lit lamp very efficaciously and helps promote scientific fervor among students with and without chemistry background.

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Demonstration of Composition Changes in a Distillation Column by Use of Bromophenol Blue Indicator

Cited by 3 publications

References 5 publications

Visually Tracking Acid–Base Extractions Using Colorful Compounds

Visually Tracking Acid–Base Extractions Using Colorful Compounds

A Multioutcome, Guided Inquiry-Based Liquid–Liquid Extraction Laboratory for Introductory Organic Chemistry

Demonstration of Acetylene–Air Flame by Hydrolysis of Calcium Carbide to Rid Blind Beliefs and Misconceptions Regarding Purported Water Lit Lamp

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