Indicators In Acid-base Titrations Research Articles

POTENTIAL OF DAYAK ONION SKIN (ELEUTHERINE PALMIFOLIA) EXTRACT AS AN ALTERNATIVE INDICATOR FOR ACID BASE TITRATION PRACTICUM

Synthetic indicators such as phenolphthalein are used during acid-base titrations to determine the end point of the titration. These indicators are not environmentally friendly and the price is high. To overcome this, it is necessary to study the potential of natural indicators available in the environment, one of which was Dayak onion skin which has not been utilized after the tubers have been taken as an anti-cancer herbal medicine. The aim of this research was to determine the potential of Dayak onion skin (Eleutherine Palmifolia) as a natural indicator in acid-base titrations. The sampling collection of Dayak onions was done randomly in the city of Palangka Raya, Central Kalimantan. The method used in this study employed experimental techniques in the chemistry laboratory of FKIP ULM with the following steps: 1) Maceration of smoothed Dayak onion skin with 96% ethanol for 1, 2 and 3 days 2) Qualitative test of anthocyanin, color test with buffer pH 1-14, 3) Absorption measurement with a UV-Vis spectrophotometer at a wavelength of 200 - 400 nm, 4) Application of the extract as an indicator in acid-base titrations. The results showed that the optimum maceration time was on day 3 with an absorption of 4,520 at a wavelength of 380 nm. The application on the HCl – NaOH titration with a titration end point volume of 9.11 mL showed a color change from yellow to straw yellow, while the comparison indicator PP had a volume change of 8.57 mL with a color change from colorless to pink. The CH3COOH – NaOH titration gave a result of 11.43 mL and the PP indicator was 11.01 mL. For the NaHCO3 – HCl titration, the end point volume of the titration was 9.93 mL with a straw yellow – yellow color change and the MO indicator comparison was 10.27 mL with an orange – red color change. From the results of this research, there was a significant color change at the end point of the titration, so it can be stated that Dayak onion skin extract had the potential to be an alternative indicator in acid-base titration practice so that it can be a solution in reducing chemical pollution in the environment.

Phytochemical Content of Fresh Purple Sweet Potato (Ipomea batatas L.) Extract As Acid-Base Titration Indicator

Research has been carried out to examine the extraction and application of purple sweet potato tuber extract as an indicator of acid-base titration. Purple sweet potato tuber extract was obtained by extracting fresh tubers using ethanol 95% medical grade (PSPTE-95%) and ethanol 96% analytical grade (PSPTE-96%). Three variations of the maceration stage extracted samples. The extract was used for a phytochemical test and applied as an indicator for acid-base titration. Based on the research conducted, the rendement extract was extracted by ethanol 95% medical grade (PSPTE-95%) for the three stages of maceration are 4.34%, 4.76%, and 5.64%, the rendement extract was extracted by ethanol 96% analysis grade (PSPTE-96%) for the three stages of maceration are 7.09%, 12.16%, and 20.43%. PSPTE-95% and PSPTE-96% contain flavonoids, tannins, alkaloids, and saponins. PSPTE-95% and PSPTE-96% can be applied as indicators for titration of HCl solution with NaOH solution and HCl solution with NH4OH solution.

Allamanda blanchetii flower extract as an improvised indicator in acid base Titration

Nowadays synthetic indicators are the choice of acid -base titrations. But due to environmental pollution, cost and availability, the search for natural compounds as an acid -base indicator was started. The present study was designed to evaluate the juice extracted from flower petals of Allamanda blanchetii (Family: Apocyanaceae) as a titration indicator. A comparative study of Allamanda blanchetii flower juice, a natural indicator, with synthetic indicators like phenolphthalein, methyl orange and neutral red - methylene blue mixed indicators were carried out to evaluate the accuracy of the water extract of the flower as an acid base indicator. Promising results were obtained for Allamanda blanchetii flower extract when compared against standard synthetic indicators. Titration shows sharp colour change at the equivalence point. The equivalence points obtained by the flower extract coincide with the equivalence point obtained by standard indicators. This natural indicator is found to be very useful, economical, simple and accurate for acid base titrations. According to all the evidence obtained after titrimetric analysis, the water extract of the flower shows effective and accurate results as that of synthetic indicators in acid base titrations. The advantage of using natural indicators in titrations is that, they can be prepared freshly and they are economical and ecofriendly.

Studi Morfologi Stomata Daun Glodokan (Polyalthia longifolia Sonn) pada Lingkungan Berbeda

Abstract. This study investigated a natural acid-base indicator which is extracted from plants in Kupang city. There are 14 plants that potential as a source of natural indicator for acid base titration, i.e, KolUngu (Brassica oleracea Capitata Group), Turi Merah flower (Sesbania grandiflora L. Pers), BelimbingWuluh flower (Averhoa bilimbi L), Kaktus Merah fruit (Opuntia vulgaris Mill), Ruelia flower (Ruellia simplex), Flamboyan flower (Delonix regia), bugenvil flower (Bougainvillea spectabilisWilld.), Bayam Merah leaves (Amaranthus tricolor L.) Jamblang fruit (Syzygiumcumini L.), Murbey fruit (Morus alba L.), Pinang fruit (Areca catechu L.), Sirih fruit (Piper betle L.), Kunyit (Curcuma longa Linn), and Nanas Kerang leaves (Rhoeo discolor). Plants extract shows a sharp color change in acid and base solution. Promising results as a natural indicator also shown in acid base titration which is have similar equivalent point to synthetic indicator. We can use these natural indicators as an alternative to synthetic indicator because they are found to be simple, very useful, cheap, easy to extract, accurate, and eco-friendly. Keywords: plant, natural indicator, acidbase.

Inventarisasi Tanaman Berpotensi Sebagai Indikator Asam-Basa Alami Di Kota Kupang

Abstract. This study investigated a natural acid-base indicator which is extracted from plants in Kupang city. There are 14 plants that potential as a source of natural indicator for acid base titration, i.e, Kol Ungu (Brassica oleracea Capitata Group), Turi Merah flower (Sesbania grandiflora L. Pers), Belimbing Wuluh flower (Averhoa bilimbi L), Kaktus Merah fruit (Opuntia vulgaris Mill), Ruelia flower (Ruellia simplex), Flamboyan flower (Delonix regia), bugenvil flower (Bougainvillea spectabilis Willd.), Bayam Merah leaves (Amaranthus tricolor L.) Jamblang fruit (Syzygium cumini L.), Murbey fruit (Morus alba L.), Pinang fruit (Areca catechu L.), Sirih fruit (Piper betle L.), Kunyit (Curcuma longa Linn), and Nanas Kerang leaves (Rhoeo discolor). Plants extract shows a sharp color change in acid and base solution. Promising results as a natural indicator also shown in acid base titration which is have similar equivalent point to synthetic indicator. We can use these natural indicators as an alternative to synthetic indicator because they are found to be simple, very useful, cheap, easy to extract, accurate, and eco-friendly. Keywords: Plant, Natural indicator, Acid-Base

Investigation of Acid-Base Indicator Property of Plumbagin from Plumbago zeylanica Linn.

There has been an increasing interest in the search for colour indicators of natural origin for titrimetric analysis. This is due to some challenges associated with the currently used synthetic ones. This study evaluates and validates the acid-base indicator property of plumbagin isolated from Plumbago zeylanica Linn. Plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) was isolated from the roots of Plumbago zeylanica Linn using silica gel chromatography and characterized using spectroscopic methods in comparison with those reported in the literature. Its acid-base indicator property was evaluated alongside phenolphthalein and methyl orange, after it was found to exhibit a sharp change in colour at various pH ranges. The plumbagin indicator was successfully used to assay ibuprofen powder and tablets (400 mg) using the British Pharmacopoeia (2013) method. Data obtained were analyzed statistically by Student's t-test and one-way ANOVA in GraphPad Prism (version 5.01, 2010). Analysis of the use of the plumbagin indicator in acid-base titrations between strong acids and strong bases and between weak acids and strong bases has been evaluated and validated according to the ICH guidelines. Plumbagin use in ibuprofen powder and tablets has also been verified. Plumbagin has been validated for use as an indicator suitable for different acid-base titrations and the analysis of ibuprofen.

Effectiveness of Calotropis Gigantean Linn Flower Extract as Indicator for Acid-Base Titration and Development of Litmus Paper

Effectiveness of Calotropis Gigantean Linn Flower Extract as Indicator for Acid-Base Titration and Development of Litmus Paper

ETHANOLIC EXTRACT OF ARISTOLOCHIA BRACTEOLATA FLOWER AS A NATURAL INDICATOR FOR ACID-BASE TITRATION

In acid-base titration or acid-base neutralization reaction the change in color due to change pH of the solution is caused due to a third substance which is termed as acid-base indicator or pH indicator. Every indicator shows different range of colors at different pH ranges. Synthetic indicators have been widely employed as indicators in acid-base titrations; however, due to environmental pollution, availability and cost, natural compounds are best alternates. Natural pigments in plants are highly colored substances and may show sharp color changes with variation in pH. In the present study an attempt has been made to extract natural indicator from flower of Aristolochia bracteolate. The equivalence points of the titrations namely strong acid-strong base, strong acid-weak base, weak acid-strong base and weak acid weak base titrations, using flower extract of A. bracteolate were coincident with the equivalence points obtained by the synthetic indicator phenolpthalein. From the results of the study, it may be concluded that ethanolic extract of A. bracteolate flower as an indicator for acid-base titration could be effectively employed as a substitute to the synthetic acid-base indicators.

Extraction of anthocyanins from purple cabbage (brassica oleracea) and red onion (allium cepa) as substitutes for synthetic ph indicators of origin

The purpose of this work is to extract anthocyanins from cabbage and purple onions, and use them as a substitute for synthetic indicators are costly, toxic to health and pollute the environment. Anthocyanins will be used to qualitatively identify the acidic, neutral and basic character of different substances and as indicators in acid-base titrations. Currently, the indicators used in the laboratory come from a synthetic origin, as is the case of phenolphthalein where the European regulations consider it as a potentially toxic product and recommend the replacement by less dangerous products. The methodology used to extract the anthocyanins was an aqueous extraction, using water as a solvent and heating for approximately 10 minutes, subsequently the indicator was stored in an amber bottle to prevent the degradation of anthocyanins and followed by this the pH was determined of substances such as: bicarbonate, lemon juice, milk, chlorine, egg white and water was determined of substances such as: bicarbonate, lemon juice, milk, chlorine, egg white and wáter. The pH results of these substances were compared with that reported in the literature, in the case of bicarbonate there was a deviation of 20%, while in the other substances it was less than 14%. In conclusion, anthocyanins from purple cabbage function as a natural indicator of pH, studies in conservation methods is a promising system for use in laboratory pedagogical applications.

Study of Acid-base Indicator Property of Ethanolic Extract of Nerium indicum Flower

A study has been done to investigate the indicator property of ethanolic extract of Nerium indicum. The commonly used synthetics indicators cause environmental pollution and pose hazardous effects in human body. Natural pigments in plants are highly coloured substance and may change with pH variation. The equivalence points of the titrations using flower extract is almost close or coincide with that of phenolphthalein (synthetic indicator). Therefore, use of ethanolic extract of Nerium indicum as an indicator for acid-base titration could be effectively employed as a substitute to the synthetic acid-base indicators.

Boerhavia Erecta Linn. Stem Bark Extract A Natural Acid-Base Indicator

Synthetic indicators have been tried as indicators in acid-base titrations but due to environmental pollution, availability and cost, natural compounds are best alternate. Natural pigments in plants are highly colored substances and may show sharp color changes with variation in pH .An attempt has been made to extract natural indicator by maceration from stem bark of Boerhavia erecta Linn. The equivalence points obtained by the BEI strong acid-strong base, strong acid-weak base, weak acid-strong base and weak acid weak base titrations were coincident with the equivalence points obtained by synthetic indicators. Thus natural indicator was found to be eco-friendly, economical, simple and accurate for all acid-base titrations. Phytochemical analysis and spectral studies confirmed presence of anthocyanins and flavonoids in BEI responsible for accurate and sharp colour change at equivalence point. The present study reports the use of this natural indicator in different acid base titrations.

An Alternative to Synthetic Acid Base Indicator-Tagetes Erecta Linn

The present work highlights the use of the methanolic extract of the flowers of Tagetes erecta as an acid-base indicator in acid-base titrations. This natural indicator is easy to extract as well as easily available. Indicators used in titration show well marked changes of colour in certain intervals of pH. Most of these indicators are organic dyes and are of synthetic origin. Today synthetic indicators are the choice of acid-base titrations. But due to environmental pollution, availability and cost, the search for natural compounds as an acid-base indicator was started. Herbal indicators are evaluated by using strong acid-strong base, strong acid-weak base, weak acid-strong base and weak acid weak base. In all these titrations the methanolic extract of the flowers of Tagetes erecta was found to be very useful, economical, simple and accurate for acid base titration.

Use ofTerminalia catappafruit extract as an indicator in acid-base titrations

Terminalia catappa L. (tropical almond), family Combretaceae, is a large deciduous tree, originally from India. It thrives as an ornamental tree in many tropical cities of the world. The present work highlights the use of the acidified methanol extract of the outer cover of Terminalia catappa fruits as an acid-base indicator in different types of acid-base titrations. It is found to be a very useful, economical, simple, and accurate indicator for said titrations.

Utilização do extrato bruto de frutos de solanum nigrum L no ensino de química

As antocianinas, pigmentos da classe dos flavonóides, são os principais substâncias cromogênicas encontrados nas flores vermelhas, azuis e púrpuras. Uma das principais características das antocianinas, com aproveitamento didático é a sua mudança de coloração em função do pH do meio. Este trabalho se insere em um projeto mais amplo, que visa propor experimentos simples e de baixo custo para ensino, utilizando-se de vegetais facilmente encontrados no Brasil. Os corantes utilizados se prestam ao ensino desde conceitos básicos de equilíbrio químico para estudantes de ensino médio, de indicadores em titulação para cursos de química geral e até da Lei de Lambert-Beer e de Espectros de Absorção, para cursos de instrumentação. A espécie utilizada foi Solanum nigrum L (maria-preta), cujo extrato bruto foi utilizado como agente cromóforo. Usando o extrato bruto como indicador em titulações ácido-base, observaram-se erro relativos da ordem de 0,11-1,0%, quando comparado com os resultados potenciométricos. A mudança de cor observada foi de vermelho para amarelo, entre pH 4 e 10. Espectros de absorção na região do UV e do visível foram obtidos em diferentes pH, para determinação dos comprimentos de onda dos máximos de absorção, bem como para demonstração da mudança da forma destes espectros em função da acidez do meio.

A new polyelectrolyte with acid-base indicating properties

Poly(styrene-co-acrylic acid) on sulfonation with concentrated sulfuric acid exhibits an unusual acid-base indicating property: an intense purple colour in alkali which changes sharply to yellow at the equivalence point. The acid-base indicating property of the polymer can not be explained by the simple structure of the sulfonated copolymer. On the basis of infrared and nuclear magnetic resonance studies it is suggested that the copolymer during sulfonation undergoes an internal Friedel Crafts acylation followed by cyclic dehydration leading to a conjugated structure. A possible mechanism is proposed for the colour change with change in pH. The copolymer was prepared also in form of spherical beads which can be used repeatedly as indicator in acid-base titrations.

3-(Arylsulphonyl)-2,4-dimethyl-3H-1,5-benzodiazepines as indicators for acidimetric titrations

1 .0~ alcoholic solutions of 3-(4-methylphenylsulphonyl) 2,4 dimethyl 3H 1,5 benzodiazepine (I), 3 (4 hydroxy 3 carboxyphenylsulphonyl) 2,4 dimethyl-3H-1,5-benzodiazepine (II), 3-(4-hydroxy3 carbomethoxyphenylsulphonyl) -2,4dimethyl3H1,5-benzodiazepine (III) and 3-(4-hydroxy-3-carboethoxyphenylsulphonyl)-2,4-dimethyl3H 1,5-benzodiazepine (IV) were found to be very good indicators in acid-base titrations. The colour change is from pale yellow (in alkaline medium) to violet (in acid medium). It is very sharp and can be judged visually with great ease. 1 Part of indicator can be detected in 20000 parts of water. F rom detailed experiments it could be concluded that the indicators are useful if a weak base is titrated against a weak or strong acid. Most satisfactory results were obtained with indicator IV. Its colour change takes place within the pH-range from 6 . 9 5.2. With the other indicators this range is more or less the same.

The use of indicators in acid-base titrations in liquid ammonia

The p K values in liquid ammonia for acid-base indicators have been bracketted using buffer solutions prepared from acids with known p K values in liquid ammonia. The application of these indicators to some practical acid-base titrations has been demonstrated.

The use of 2,6-dichlorophenolindophenol as indicator in acid-base titrations

2,6-Dichlorophenolindophenol shows acid-base indicator properties. Its colour is red in acidicmedia and blue in alkaline media. 'Ihe transitional pH value is 5.7 and the colour change is sharp and easy to observe. The use of the indicator in various acid-base titrations, as well as the effects of neutral salts, alcohol and temperatures, were checked. The absorption spectra of the acidic and basic forms of the indicator are presented.