Figure 3 - uploaded by Olufunmilayo Deborah Ayodele
Content may be subject to copyright.
Source publication
Acid-base titrations are the main part of volumetric analysis in the secondary school chemistry practical syllabus in Nigeria. Synthetic indicators are generally used in teaching students the procedure and skills required in acid-base titrations. However, some of these synthetic indicators are not readily available, some are toxic and there is a sp...
Context in source publication
Context 1
... plant is known generally as Chinese hibiscus, shoeblack plant, tropical hibiscus or China rose. It is a species of tropical hibiscus, a flowering plant in the Hibisceae tribe of the family Malvaceae, native to East Asia ( Figure 3). It contains anthocyanins and comes in orange, pink, red white and yellow. ...
Citations
... These natural pigments undergo distinct colour changes in response to changes in pH levels, providing visible and identifiable indicators. 10 Furthermore, these plant-based pH indicators demonstrate impressive durability and resistance to environmental factors and can be used in the long term. 11 Another significant advantage is the ease of accessibility and affordability of these plant species. ...
Purple cabbage, turmeric, magenta, amaranth, and red beet contain colour anthocyanins. These colours change according to pH environments. This research aims to explore the potential of utilizing various plant species, such as purple cabbage, turmeric, magenta, amaranth, and red beet, to develop pH indicator paper. The colour solutions of these plants were extracted with deionized water. The extracted solutions were analyzed by IR spectraand UV-Vis spectra. The peak of OH, C=O, and C-O in IR spectrachangedinalkaline, neutral, and acidic environments, respectively. The maximum absorption wavelengths of the extracted solutions in UV-Vis spectrawere 533 nm and 600 nm in alkaline and neutral environments, respectively. The pH indicator paper was created by impregnating plain white computer paper with extract solutions to achieve uniform colouration. These prepared pH indicator papers were used to detect the pH of household chemicals, including milk, soap, toothpaste, and various fruits and vegetables. The study demonstrates that these plant species exhibit excellent sensitivity to different pH values, possess good durability, and remain unaffected by environmental factors. The developed pH indicator paper holds promising practical applications for testing the pH of diverse chemicals. In this study, the pH indicator paper was employed to determine the acidity or alkalinity levels of commonly found household items, including fruits, beverages, and cleaning solutions. The results highlight the versatility and convenience of utilizing plant-based pH indicator paper for monitoring pH variations in daily life applications
... Such types of indicators may have toxic effects, cause environmental pollution, high cost, less availability and sometimes low color range (Bhagat, Patil, Channekar, Shetty, & Akarte, 2008;Kadam, Yadav, Raje, & Waghmare, 2013). Despite these, natural indicators extracted from plants like onion, cherry, blueberry, beetroot, red cabbage, peach, pear, grapes, tomato, rose, turmeric, etc. are safe, less expensive, easily available, have fewer side effects, biodegradable, green and eco-friendly (Ayodele, Hawa, & Tawakalitu, 2020;Ogbuanu & Ike, 2018;Pathade, Patil, Kondawar, Naikwade, & Magdum, 2009). Such indicators are highly colored, simple, easy to extract and show promising results as compared to synthetic indicators in the titrimetric analysis (Gyanodaya, Mandir, & Narsingarh, 2015;Jaspreet, Kanika, Nain, & Geeta, 2011). ...
A substance that changes color when pH changes is referred to as an indicator. Synthetic indicators, which are expensive and toxic, are currently the best option for estimating acid-base concentrations or hydronium and hydroxide ion concentrations. This study aims to prepare pH paper indicators from natural sources to overcome this problem. Indicator strips of this type are eco-friendly, cheap, durable, non-toxic, biodegradable, and easy to prepare even at home. In this application, we are using natural sources such as turmeric (Curcuma longa), rose (Rosa Indica), beetroot (Beta vulgaris), and red cabbage (Brassica oleracea) for the preparation of pH paper indicator strips. We used 73 acids, bases, and neutrals solutions to conduct comparative studies. These include fifty-nine household chemicals, such as milk, lemon, mango, honey, glycine, etc., and fourteen standard solutions of acids and bases of pH from 1 to 14. By dipping yellow-colored turmeric acidic paper into sodium hydroxide, we transform yellow-colored turmeric acidic paper into red-colored turmeric basic paper. The results are the same in both cases, i.e., turns yellow in acids and red in bases but unaffected in neutrals. Rose paper easily differentiates acids and bases while red cabbage gives almost the same results as pH paper (wide color change from red to dark blue). As these can be easily prepared and give comparable results with commonly used paper indicators, it would be possible to replace synthetic paper indicators
An Indicator is an organic substance which shows a wide range of colour changes depending on the relative proportion of hydrogen or hydroxide ions present in solution of that substance. In long search for less hazardous and eco-friendly chemical substances from natural products several scientists had extensively work on the use of flower extract as indicators and has proof to be effective. About 40g each of the flower petals were washed and grounded in a mortar with a pestle, and transferred into two different beakers one containing 400cm 3 of ethanol and the other 400cm 3 of distilled water and macerated carefully for about 48hours. The colour from the petals in the extract was cooled and filtered into a clean, labeled bottles with a stopper. The aqueous and ethanolic flower extract were tested with acid and base solutions to determine their colours in different media. Drops of the extracts were added into each 25cm 3 of 0.1M NaOH and 0.1M NH4OH and standardized with 0.1M HCl solution. The result revealed that the Cassia sieberiana DC extract colour is yellow in acid and orange in base. This property coincides with that of standard indicators used (Phenolphthalein and Methyl Orange) which shows different colours in acidic and basic media. From the titration results of strong acid against strong base and strong acid against weak base show that the end point obtained for the Extract is closely related to that of synthetic indicators (phenolphthalein and methyl orange). The dye from the aqeuos extract has a λmax at 500nm while that of the ethanolic extract has a λmax at 520nm This results reveals that even the Cassia sieberiana DC extracts is suitable for strong acid-strong base and strong acid-weak base titrations in place of synthetic indicator.
