The Potential of Clitoria ternatea L. Extracts as an Alternative Indicator in Acid-Base Titration

Experiments are an important part of the chemistry curriculum. An indicator in the form of a synthesis indicator is commonly used in acid-base materials experiments. The usage of synthetic indicators can result in waste that is both environmentally harmful and costly. The butterfly pea flower is one of the plants that contains anthocyanins, which have the potential to be used as an alternative indication of natural acids and bases. The study aims to determine the acid and base material curriculum and competency indicators, as well as the potential of butterfly pea flower extract as a substitute for synthesis indicators and the practicality of butterfly pea flower extract as a chemical experimental design in SMA/MA. This study employs a descriptive qualitative research method that includes literature review, observation, experimentation, and interviewing. The results showed that the relationship between acid-base materials and experiments was the determination of natural materials as acid-base indicators, the pH of the solution, the identification of acid-base properties, and acid-base titration. The butterfly pea flower indicator was produced from maceration extraction using 96% ethanol as the solvent. The butterfly pea flower indicator gives pink color at pH 1-2, reddish purple at pH 3, light purple at pH 4-5, turquoise at pH 6, bluish green at pH 7, light blue at pH 8-9, green at pH 10, yellowish green at pH 11, greenish yellow at pH 12-13, and yellow at pH 14. The titration step showed that butterfly pea flower indicators could replace synthetic indicators, namely phenolphthalein and methyl orange. Based on the analysis, the butterfly pea flower indicator can be used as an alternative indicator in acid base titration and an alternative experimental design in schools.

Comparison of Color Change to pH Range and Acid-Base Titration Indicator Precision Test of Multiple Ethanol Extracts

Natural indicators using anthocyanin compounds can be an alternative to synthetic indicators on acid-base titration because anthocyanin is an organic compound that is unstable with changes in pH. The extraction was carried out with ethanol because the compounds of anthocyanin were polar. This study was to ensure an ethanol extract of some plants could be used as an acid-base indicator that had a pH range of color change and the value of the equality parameter was not significantly different from the phenolphthalein indicator. The research method is to collect research journals on making natural indicators from ethanol extracts of various plants compared to phenolphthalein indicators so that secondary data from these journals can be processed statistically. Research results and conclusions: Based on the results of statistical data processing using the t-test there was no difference in the average pH of the phenolphthalein indicator with the average pH of ethanol extracts of adam air leaves (Rheo discolor), white frangipani flowers and Clitoria teratea L., with a significance value > 0.05 and the equality test (precision) had the requirements of good equality. HIGHLIGHTS Natural indicators are needed as a substitute for synthetic indicators in determining acid-base titrations; one of them is anthocyanin dye Research journals on making natural indicators from ethanol extracts of various plants compared to phenolphthalein indicators so that secondary data from these journals can be processed statistically There was no significant difference between the average pH of the phenolphthalein indicator and the average pH of the ethanol extract of Adam's Eve Leaves, ethanol extracts of white Cambodia flowers and ethanol extracts of Telang flowers in producing color changes GRAPHICAL ABSTRACT

NEW ACID-BASIC INDICATORS: RESEARCH USING A SMARTPHONE

Modern cameras, desktop scanners, smartphones allow not only registering an image, but also determining its color characteristics. That allows us to quickly, objectively and automatically determine the color characteristics of colored samples in acid-base titration, because there is a significant error at visually determining the pH range of the color transition. In analytical chemistry the characteristics of acid-base indicators are very important, in particular their pH transition interval. But the disadvantage of most indicators is the wide range of color transition: from 1 to 3 pH units. The aim of this work is to find new acid-base indicators that change color in an alkaline environment and have a narrow pH range of the color transition. We have developed the apparatus and technique of convenient and highprecision simultaneous determination of the pH of the medium and the color of the acidbase indicators. In acid-base titration the PH measurements were performed with a combined glass electrode AD1131 by рН-meter AD1000. The color transition was determined with help of a smartphone with the subsequent processing of the results by computer software. The color characteristics were measured for each channel of the RGB model in the range from 0 to 255. Our apparatus is small and mobile, and allows us simultaneously to measure the pH of the medium and accurately to determine the color characteristics. As a result, we can construct graphical dependencies of color on pH for each channel of the RGB model. We found the N-arylsulfonyl-2-aroylamido-1,4-benzo(naphto)quinone monoimines and 2,5-dibenzoylamido-1,4-benzoquinone are good acid-base indicators. They “work” in the pH range from 8.82 to 11.35 and have a very narrow color transition interval from 0.10 to 0.61. Solutions of these compounds in an alkaline medium have bright intense colors due to formation of mesomeric ions. That allows using of these indicators in the titration of weak acids with strong bases and vice versa by the method of neutralization.

Volumetric Analysis

Volumetric Analysis describes the general process of quantifying acid-base reactions by titration in which the known concentration of one solution (often a standard solution) is used to determine the unknown concentration of another. Common terms are defined, and calculations involving acid-base titration based on the concept of reaction stoichiometry, number of moles, mole ratio and molarity are discussed. The treatment is then broadened to include calculations involving mass and percentage of substance titrated. Back (or indirect) titration, a method to determine the concentration of a volatile substance or an unknown solid that is insoluble or only partly soluble in water, is described. The Kjeldahl method of determining the nitrogen content in organic and inorganic samples is used to illustrate back titration.

Isolation of Natural Acid Base Indicator from the Flower Extract of Sarca Asoca, Abelmoschus Esulentus, Hibisucs Cannabinus And Hibiscus Rosa Sinensis

The objective of this work is to use more plant indicators than chemical based indicators. Saraca asoca is a species of family Fabaceae and Abelmoschus esculentus and Hibiscus cannabinus is a species of family Malvaceae [1]. Indicator are very special chemicals, they change colour of the solution with change in pH by adding acid or alkali. In the present work acid base titration has been performed by using natural indicators. The natural indicator is prepared from the most commonly occurring flower Hibiscus cannabinus, Abelmoschus esculentus Saraca asoca and Hibiscus Rosa sinensis. Aqueous and methanolic extract of flower were used as natural indicator. One acid one base were selected for acid base titration. Vinegar is used as acid and caustic soda is used as base. The results obtained by the natural indicator are almost similar to the result given by the synthetic indicators. Thus, natural indicator from flowers can be used for acid base titration [2]. Using aqueous extract of flower as indicator is more economical and with the same accuracy of result as that given by synthetic indicators.

The characteristics of chemistry test items on nationally-standardized school examination in Yogyakarta City

This study aimed to describe the characteristics of chemistry test items in Nationally Standardized School Examination or Ujian Sekolah Berstandar Nasional (USBN), consisted of discrimination index, difficulty index, and question reliability. The data was collected by using documentation of the answers of 194 students. The type of research was descriptive exploratory with quantitative and qualitative approaches. Quantitative data analysis was performed by using classical test theory approach and item response theory with 1 logistical parameter. Meanwhile, qualitative data analysis was conducted in order to describe the items that were categorized as difficult and bad categories. The results showed that according to classical test theory, USBN Chemistry item test had an average level of difficulty of 0.57 which was categorized as moderate. Regarding to the discrimination index, the average of different test power obtained were equal to 0.146, and belonged to the good category. Based on the item response theory, the average of difficulty index of -0,00086 was categorized as moderate. The results of the estimated reliability of the questions amounted to 0.48 included in the moderate category. The results of the qualitative analysis showed that the items which belonged to difficult category were the items on salt hydrolysis material, acid-base titration, the concept of periodicity, manufacture and use of chemical compounds according to classical test theory. Meanwhile, according to the theory of response, items which belonged to difficult category were found in acid-base titration material, the solution colligative phenomenon, and the concept of periodicity of the main metal elements.