Titration of strong acid

CHjCiMeljCHjCO-U.sed as indicators in the titration of strong acids or strong bases... 

Directions are provided for the quantitative analyses of Ck and P04 , and for conducting titrations of strong acids and strong bases. 

Titration of Strong Acid with Strong Base... 

Figure 6.19. Conductometric titration curves (a) Titration of strong acid with NaOH. (b) Titration of acetic acid, K, = 1.75 x 10 3 mol dm" with NaOH. (c) Titration of boric acid Jf,= 6x 10" io mol dm" J with NaOH. (d) Titration...

When a solution of standard base is used only for titration of strong acids, a small amount of carbonate is not a serious source of error provided the end point is taken with an indicator that changes color at a pH of about 4 or 5. For standardizing such carbonate-containing solutions, potassium hydrogen phthalate is an unsuitable primary standard. An alternative is pure potassium chloride, which is passed through a cation-exchange column, converted to hydrochloric acid, and titrated with the sodium hydroxide. 

For the titration of strong acids of concentration 0.1 M or higher with base containing some carbonate, the error involved in titrating to a pH of 4 is negligible. For the titration of more dilute solutions, however, it is advisable (Section 6-3) to titrate to the first perceptible color change of methyl red (pH range 4.4 to 6.0), boil to remove carbon dioxide, cool, and continue to the yellow color of the indicator. 

Use the search engine Google to locate the Web document The Fall of the Proton Why Acids React with Bases by Stephen Lower. This document explains acid/base behavior in terms of the concept of proton free energy. How is an acid/base titration described in this view In a titration of strong acid with strong base, what is the free energy sink In a complex mixture of weak acid/base systems, such as serum, what happens to protons ... 

Figure 15-1 Curves for the titration of strong acid/weak acid mixtures with 0.1000 M NaOH. Each titration is on 25.00 mL of a solution that is 0.1200 M in HCl and 0.0800 M in HA.

Thus, for the endpoint, the left-hand side of Eq, (5.75) disappears, and we calculate an endpoint pH of 7.0. In fact, all titrations of strong acids with strong bases, and vice versa, will have their endpoint at pH = 7. 

The analytical concentration of strong acid was determined by a back-titration of an added excess of standard hydrogen carbonate with standard hydrochloric acid. Iodine was first reduced by thiosulphate in order to allow visual indication of the end point in the titration. The end point corresponds to the titration of strong acid plus almost all of the selenious acid. Hence, a blank titration was carried out on a solution of selenious acid of the same concentration as the test solution. 

One can of course fit experimental data to the entire, theoretical curve with a non-linear least-squares routine such as Solver. In this particular case, however, the direct, non-iterative method of using Gran plots provides a valid, simpler alternative. As illustrated below, such plots are quite linear, analogous to the Gran plots for the titration of strong acids and bases. 

Figure 4.57. FI A titration of strong acid with strong base. The manifold (a) comprises a mixing chamber G, having a volume of 0.98 mL, where a well-defined concentration gradient is formed of the injected acid sample zone within the alkaline carrier solution, which also contains an acido-basic indicator. The flowthrough cell monitors colorimetrically the change of the indicator from blue to yellow as shown on the record in (b). As the color of the indicator is converted completely during each titration cycle, all curves have the same height, while their width, Ar, is a function of their individual concentration.

The manifold used for acido-basic titrations of strong acid with strong base using bromothymol blue as indicator added directly to the alkaline carrier solution is shown in Fig. 4.60a, while the recorder output is shown in Fig. 4.60 7. Here, all the five titration cycles made are recorded from the same starting point (5), showing the practical consequences of performing titrations at medium D values. First, the titration cycle, including the washout period, can be made as short as 12 s with an equivalence A/ of 2.2 s hence, it is necessary to acquire the readouts by means of a... 

In this context a very important aspect of the FIA titration procedure should be emphasized [253] From Eq. (4.6) it is apparent that At may be varied by changing the concentration of the titrant solution (Cb), that is, the dynamic measuring range of the procedure may be shifted as a function of Cb- This is readily demonstrated in Fig. 4.61, which shows a series of calibration runs of titration of strong acid (HCl) with strong base... 

TITRATION OF STRONG ACID WITH STRONG BASE... 

Hydrolysis of salts of weak acids and bases. In aqueous solution the end-point in titrations of strong acids with strong bases, or vice versa. 

You have read about titrations of strong acids with strong bases, weak acids with strong bases, and weak bases with strong acids. What if you titrated a weak acid with a weak base Sketch a pH curve and defend its shape. Label the equivalence point and discuss the possibilities for the pH value at the equivalence point. 

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