Equivalence Points and Inflexion Points in Acid-Base Titration Curves

General equations are derived for the relation between pH and stoichiometric degree of neutralization in the titration of monoprotic and diprotic weak acids (or bases) with strong acid or strong base. From these equations the number and position of inflexion points in the curves is derived, and their relation to the equivalence points is shown. Methods for determining ionization constants from inflexion points are discussed.

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Utilization of Extract of Sambang Getih Leaves (Hemigraphis colorata. Hall. F) as a Acid-Base Indicator

Jurnal Akademika Kimia ◽

10.22487/j24775185.2020.v9.i1.pp7-15 ◽

2020 ◽

Vol 9 (1) ◽

pp. 7-15

Author(s):

Eksari Ekasari ◽

Purnama Ningsih

Keyword(s):

Leaf Extract ◽

Strong Acid ◽

Weak Base ◽

Acid Base ◽

Strong Base ◽

Unique Color ◽

Acid Base Titration ◽

Naoh Solution ◽

Ph Range ◽

Color Pigment

Getih sambang leaves (Hemigraphis Colorata. Hall. F) are plants that have a distinctive and unique color, namely the upper surface of the leaf is green and the bottom of the leaf is burgundy where sambang leaves contain anthocyanin compounds. Anthocyanin is the color pigment in plants that forms the basis of the use of natural indicators. This study aims to prove whether getih cucumber leaves can be used as an acid-base indicator, to determine the type of acid-base titration that is suitable for indicators of getih cucumber leaves, and to find out what the pH-changing color route of getih cucumber leaves is. The method used is extraction, namely maceration. Wee leaves are macerated by using methanol as a solvent for 24 hours. The extract was previously tested using HCl solution and NaOH solution as a test to prove the presence of anthocyanin. The results obtained in this study, getih sambang leaf extract can be used as an indicator of acid base, and also the type of acid-base titration that is suitable for use in the indicator of getih leaf extract extract precisely on the titration of strong-base strong acid, and strong weak base-acid It is best used as a substitute for the phenolphthalein indicator. In titration of strong and weak acids and bases, it is good to be used as a substitute for the indicator of methyl orange. The pH range obtained from the getih sambang leaf extract is pH 4-7 (red-purple).

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Utilization of Kalpataru Flower Extract (Hura crepitans Linn) as an Alternative Acid Base Indicator

Jurnal Akademika Kimia ◽

10.22487/j24775185.2020.v9.i3.pp148-157 ◽

2020 ◽

Vol 9 (3) ◽

pp. 148-157

Author(s):

Bayu Riswanto ◽

Sitti Aminah

Keyword(s):

Strong Acid ◽

Weak Acids ◽

Acid Base ◽

Flower Extract ◽

Weak Bases ◽

Base Solution ◽

Acid Base Titration ◽

Hura Crepitans ◽

Dark Green ◽

Strong Acids

Kalpataru flower (Hura crepitans Linn) is an anthocyanin-containing plant. This study aims to utilize extract from the kalpataru flower as an alternative acid base indicator and determine the type of acid-base titration suitable for extracting the kalpataru flower indicator. Kalpataru flowers are macerated with methanol solvent for around 2 hours. Kalpataru flower extract was tested as an indicator in acid-base solution, buffer, and compared with phenolphthalein and methyl orange for acid-base titration, namely: strong acids with strong bases, weak acids with strong bases, and weak bases with strong acids. The results obtained in this study were: indicator extract of brownish yellow kalpataru flowers, in strong red acids, in strong bases of dark green, in weak pink acids, and in weak bases in light green. In the buffer, the indicator extract of the kalpataru flower has a range of pH pH 4-5 (pink-colorless) and pH 9-11 (yellowish green-dark green). The indicator of kalpataru flower extract can be used on strong acid titration with strong bases, weak acids with strong bases and weak bases with strong acids. Kalpataru flower extract can be used as an acid-base indicator.

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

INDIAN DRUGS ◽

10.53879/id.56.03.11502 ◽

2019 ◽

Vol 56 (03) ◽

pp. 77-79

Author(s):

G Vambhurkar ◽

A. Jagtap ◽

A. Gavade ◽

M Kengar ◽

M Bhutkar ◽

...

Keyword(s):

Ethanolic Extract ◽

Strong Acid ◽

Weak Acid ◽

Weak Base ◽

Acid Base ◽

Ph Indicator ◽

Strong Base ◽

Color Changes ◽

Synthetic Indicators ◽

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.

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Optical ph sensing material prepared from doped sol-gel film for use in acid-base titration

ASEAN Journal on Science and Technology for Development ◽

10.29037/ajstd.311 ◽

2017 ◽

Vol 18 (2) ◽

Cited By ~ 1

Author(s):

Musa Ahmad ◽

T.W. Tan

Keyword(s):

Sol Gel ◽

Strong Acid ◽

Thymol Blue ◽

Bromophenol Blue ◽

Ph Sensing ◽

Acid Base ◽

Strong Base ◽

Sensing Material ◽

Gel Film ◽

Acid Base Titration

An optical pH sensing material has been prepared in this study by using sol-gel technique. Bromothymol blue, bromophenol blue and thymol blue were chosen in this study as acidbase indicators for strong acid-strong base, strong acid-weak base and weak acid-strong base titration, respectively. The results show that these indicators could be successfully entrapped inside the sol-gel film and still maintain its chemical behaviour as in solution. The entrapped acid-base indicators respond well to any pH changes and could be used to determine the end-point of the acid-base titration.

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GREEN CHEMISTRY: ROSELLE’S COROLLA EXTRACT AS A SUBSTITUTE FOR HAZARDOUS INTERNAL INDICATORS IN VOLUMETRIC ANALYSIS

International Journal of Research -GRANTHAALAYAH ◽

10.29121/granthaalayah.v7.i9.2019.567 ◽

2019 ◽

Vol 7 (9) ◽

pp. 118-122

Author(s):

R. F. Pagariya

Keyword(s):

Strong Acid ◽

Weak Acid ◽

Basic Solution ◽

Phenol Red ◽

Weak Base ◽

Acid Base ◽

Ph Indicator ◽

Strong Base ◽

Synthetic Indicators ◽

Acid Base Titration

Indicators used in acid-base 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 neutralization titrations. But due to environmental pollution, availability and cost, the search for natural compounds as an acid-base indicator was started. The present work highlights the use of the ethanolic extract of the corolla of Roselle (Hibiscus sabdariffa) as a pH indicator in strong acid-strong base, strong acid weak base, weak acid strong base and weak acid-weak base titrations. This natural indicator is easy to extract as well as easily available. The results showed that the Roselle’s corolla indicator gave red color in acidic solution, while green in basic solution. The comparison indicators used in this research were phenolphthalein, methyl red and phenol red. Hopeful results were obtained when it was compared against standard synthetic indicators. The equivalence points obtained match with the equivalence points obtained by standard indicators. Therefore this natural indicator is found to be useful, economical, simple, precise and eco-friendly for acid base titration.

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An Exact Method to Determine the Conductivity of Aqueous Solutions in Acid-Base Titrations

Journal of Chemistry ◽

10.1155/2015/540368 ◽

2015 ◽

Vol 2015 ◽

pp. 1-13 ◽

Cited By ~ 3

Author(s):

Norma Rodríguez-Laguna ◽

Alberto Rojas-Hernández ◽

María Teresa Ramírez-Silva ◽

Lucero Hernández-García ◽

Mario Romero-Romo

Keyword(s):

Aqueous Solutions ◽

Electric Conductivity ◽

Functional Relation ◽

Strong Acid ◽

Equivalent Conductivity ◽

Acid Base ◽

Strong Base ◽

First Derivative ◽

Algebraic Expressions ◽

Acid Base Titration

Several works in the literature show that it is possible to establish the analytic equations to estimate the volumeVof a strong base or a strong acid (VbandVa, resp.) being added to a solution of a substance or a mix of substances during an acid-base titration, as well as the equations to estimate the first derivative of the titration plotdpH/dV, and algebraic expressions to determine the bufferβcapacity with dilutionβdil. This treatment allows establishing the conditions of thermodynamic equilibria for all species within a system containing a mix of species from one or from various polyacid systems. The present work shows that it is possible to determine exactly the electric conductivity of aqueous solutions for these Brønsted acid-base titrations, because the functional relation between this property and the composition of the system in equilibrium is well known; this is achieved using the equivalent conductivityλivalues of each of the ions present in a given system. The model employed for the present work confirms the experimental outcomes with the H2SO4, B(OH)3, CH3COOH, and H3PO4aqueous solutions’ titration.

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Flower Extracts of Cage Plants (Canavalia virosa) as an Indicator of Acid Base

Jurnal Akademika Kimia ◽

10.22487/j24775185.2020.v9.i4.pp191-198 ◽

2020 ◽

Vol 9 (4) ◽

pp. 191-198

Author(s):

Andi M. Rendi ◽

Supriadi Supriadi ◽

Suherman Suherman

Keyword(s):

Strong Acid ◽

Weak Acid ◽

Acid Base ◽

Buffer Solution ◽

Strong Base ◽

Flower Extract ◽

Acid Titration ◽

Acid Base Titration ◽

Plant Flower ◽

Light Green

Cage plants (Canavalia virosa) are classified as nuts. This study aims to prove the flowers of the cage plants as acid-base indicators and determine the type of acid-base titration that is suitable for indicators of cage plants. The flowers of the cage plants were macerated with ethanol. Extras were tested as indicators in acid-base solutions, buffer solutions, and compared with phenolphthalein and methyl orange for acid-base titration, namely: strong acid with a strong base, a weak acid with a strong base, and weak base with strong acid. The results obtained in this study, namely: flower extracts of cage plants in strong red acid, in weak acid pink, in strong green bases, and weak bases in light green. In a buffer solution of pH 1 to pH 11, the flower extract of the cage plants gives 4 color groups, namely: a buffer solution with pH 1 colored red, pH 3 colored pink, pH 5 to pH 9 being light green, and pH 11 being dark blue. Cage plant flower extract can be used as an indicator of acid-base, cage plant flower extract can be used on strong-base strong acid titration, strong weak-acid base, and weak-strong base acid titration.

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