Acid-base indicators table

Some Common Acid-Base Indicators Table 1.6.3... 

The amoimt and rate of OH formation are determined by the potential apphed. The pH in the vicinity of the foam pellets was estimated by using acid-base indicators (Table 2) the more negative the applied potential, the more basic is the medium close to the electrode. 

A list of several common acid-base indicators, along with their piQs, color changes, and pH ranges, is provided in the top portion of Table 9.4. In some cases. 

The indicator method is especially convenient when the pH of a weU-buffered colorless solution must be measured at room temperature with an accuracy no greater than 0.5 pH unit. Under optimum conditions an accuracy of 0.2 pH unit is obtainable. A Hst of representative acid—base indicators is given in Table 2 with the corresponding transformation ranges. A more complete listing, including the theory of the indicator color change and of the salt effect, is also available (1). 

Because the pH changes rapidly near the stoichiometric point, an indicator is suitable for a titration if the pH at the stoichiometric point is within one unit of p K pHstoichiometric point P In 1 Table 18-2 lists a selection of acid-base indicators, and Example shows how to select an appropriate indicator. 

Properties of Aqueous Acid-Base Indicators at 25°C. Chemical Sciences Data Tables, James A. Plambeck, 1996, http //www.compusmart.ab.ca/plambeck/che/ data/p00433.htm... 

Table 5.1 summarizes the details of some useful acid-base indicators. Exact agreement with the pH range expressed by equation (5.5) is by no means always observed. This is because some colour changes are easier to see than others and so the general approximation made in deriving equation (5.5) is not uniformly close. Structurally, the indicators form three groups phthaleins (e g. phenolphthalein) sulphonephthaleins (e.g. phenol red) and azo compounds (e.g. methyl orange). 

Table 8.4 Data on the Endpoints of Three Common Acid-Base Indicators...

For the titration of a strong base with a weak acid, the equivalence point is reached when the pH is greater than 7. The half equivalence point is when half of the total amount of base needed to neutralize the acid has been added. It is at this point that the pH = pK of the weak acid. In acid-base titrations, a suitable acid-base indicator is used to detect the endpoint from the change of colour of the indicator used. An acid-base indicator is a weak acid or a weak base. The following table contains the names and the pH range of some commonly used acid-base indicators. 

The last of these methods has been applied particularly to chemical reaction vessels. It is covered in detail in Chapter 17. In most cases, however, the RTDs have not been correlated with impeller characteristics or other mixing parameters. Largely this also is true of most mixing investigations, but Figure 10.3 is an uncommon example of correlation of blend time in terms of Reynolds number for the popular pitched blade turbine impeller. As expected, the blend time levels off beyond a certain mixing intensity, in this case beyond Reynolds numbers of 30,000 or so. The acid-base indicator technique was used. Other details of the test work and the scatter of the data are not revealed in the published information. Another practical solution of the problem is typified by Table 10.1 which relates blend time to power input to... 

Ceramics are More than Clay Alone Table 3.5 Some acid-base indicators... 

Table 3-3 TRANSITION INTERVALS OF SELECTED ACID-BASE INDICATORS...

A list of some compounds possessing acid-base indicator properties is shown in Table 2. Ethanol is the common solvent for indicator solutions. 

The table below gives the color changes of many acid base indicators used to test the pH of water. 

The point at which the color of an indicator changes in a titration is known as the end point. It is determined by the value for the indicator (Section 19-4). Table 19-4 shows a few acid-base indicators and the pH ranges over which their colors change. Typically, color changes occur over a range of 1.5 to 2.0 pH units. 

A series of acid-base indicators can be used to estimate the pH of an unknown solution. Use the values given in Table 19-4 to determine the possible range of pH values of the following solution. The solution was colorless with phe-nolphthalein, yellow with methyl orange, and yellow with methyl red. 

The indophenols. The indophenols were examined thoroughly for oxidation-reduction indicator properties by W. M. Clark and his collaborators, who observed also that they behaved as acid-base indicators. All indophenols show a color change from dark red or brownish red (in acid) to a deep blue. Unfortunately these colors do not endure. In the following table are found the values of the indicator constants (50% transformation) determined at 30° by Clark and coworkers. pKi = — log K = pH when [HI] = [I 3 ... 

Symbols and Abbreviations The Modern Periodic Table Alphabetical Table of the Elements Properties of Elements Electron Configurations of the Elements Useful Physical Constants Names and Charges of Polyatomic Ions Solubility Guidelines Solubility Product Constants Acid-Base Indicators... 

Many acid-base indicators are plant pigments. For example, by boiling chopped red cabbage in water we can extract pigments that exhibit many different colors at various pHs (Figure 16.6). Table 16.1 lists a number of indicators commonly used in acid-base titrations. The choice of a particular indicator depends on the strength of the acid and base to be titrated. Example 16.7 illustrates this point. 

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