An indicator is “a large organic molecule which works like a color dye” (Orphardt, 2003, n.p.).
Acid-base indicators could either be a weak acid or a weak base. This depends on the kind of solution being tested. The natural form of an acid-base indicator is of “different color than the iogenic form of the indicator” (Acid-Base Indicators, 2009, n.p.).
The way that it changes color depends on a range of several hydrogen concentrations and not necessarily from only one specific hydrogen ion concentration. The use of an indicator is through the process of titration. In weak acids, indicators that change through slightly alkaline conditions are titrated. Conversely, in weak bases, the titration of indicators that change under slightly acidic conditions is employed (Acid-Base Indicators, 2009, n.p.).
One of the simplest indicators is the litmus which effectively changes color when a solution of basicity or acidity is tested.
On the other hand, the electrometric measurement of the pH value is consisted of the measurement of potential difference between two special electrodes (Hydrogen-Ion Determination, 2000).
One electrode develops a potential through the hydrogen-ion concentration founds in the solution while the second electrode has a constant potential value. In making the measurement, it must be taken into consideration that the potentiometer used is at a point of balance so that no current shall be drawn from the electrodes (Hydrogen-Ion Determination, 2000).
The Essay on Acids, Bases, and Salts
The experiment allowed students to explore different electrolytes and classify them into acids, bases and salts by using different indicators or by measuring the pH levels of each. The experiment also helped students classify different substances through their conductivity properties. The preparation of a 1 M stock solution from NaOH pellets diluted to a 0. 1 M NaOH solution was also utilized in ...
The pH is defined as the “negative logarithm of hydrogen ion concentration” (Measurement of pH of Water, n.d., n.p.).
At a given temperature the acidic or basic character of a solution is indicated by pH or hydrogen ion activity. The alkalinity and acidity are the acid and base neutralizing capacities of water.
Titration is a method for an experiment wherein one known solution is used to find an unknown property of another solution. It is used in determining the pH of solutions. The titration curves involve three possibilities: that a neutral point does not yield any change, an equivalence point means tat exact amounts of solutions were mixed, and an endpoint determines that the indicator produces a color change.
References
Acid-Base Indicators. (2009).
About.com: Chemistry. Retrieved April 3, 2009 from http://chemistry.about.com/library/weekly/aa112201a.htm.
Measurement of pH of Water. (no date).
Retrieved April 3, 2009 from http://www.newagepublishers.com/samplechapter/001578.pdf.
Hydrogen-Ion Determination. (2000).Retrieved April 3, 2009 from http://www.humboldt.edu/~scimus/Instruments/Poten-Braun/pHPot-Braun.htm. Ophardt, C. (2003).
Acid and Base Indicators. Retrieved April 3, 2009 from http://www.elmhurst.edu/~chm/vchembook/186indicator.html.
