Buffer calculating

C18-0009. Addition of 5.25 g of NaOH to the buffer solution described in Example would exceed the capacity of the buffer. Calculate the concentration of excess hydroxide ion and the pH of the solution. 

Fig. 1.9 Dependence of pH on the buffer composition according to the Henderson-Hasselbalch equation (1) acidic buffer (Eq. 1.4.26) (2) basic buffer. Calculation for K A = K B = 10-4, s = 0.1 mol dm-3...

Click on Buffers. Review Preparation of Buffers, Definitions of pH, Hender-son-Hasselbalch Equation and Buffer Calculator. 

Introduction to fast performance liquid chromatography. Review Buffer preparation, Definitions of pH, Henderson-Hasselbalch equation, and Buffer calculations. 

I STRATEGY We might at some point be faced with performing a large num- ber of buffer calculations in a short period of time. So, in this second exam-] pie, for variety and brevity, we shall calculate the pH of an HA/A- buffer. from the Henderson-Hasselbalch equation, Eq. 1. To use that equation, identify the acid and base, and rearrange it to give the desired concentration i ratio. 

Preparation of an Acetate Buffer Calculate the concentrations of acetic acid (pKa = 4.76) and sodium acetate necessary to prepare a 0.2 m buffer solution at pH 5.0. 

Figure 14 Covariation of V with AI2O3 in (a) abyssal peridotites, orogenic massifs, off-craton xenoliths, arc xenoliths, and (b) cratonic xenoliths (data sources in Table 6). Shown for illustrative purposes are residue trends for partial melting at 1.5 GPa as a functions of/o (expressed relative to the nickel-nickel oxide (NNO) buffer) calculated using methods described in Canil (2002).

We can see that the error introduced by assuming that the buffer reacts completely with the added H"" is small. In the above problem, the buffer is relatively weak and the amount of H"" ion added is of the same order of magnitude as the original A" concentration. In practice, the concentration of the buffer employed would be high compared to the expected change in (or OH") ion concentration. Consequently, buffer calculations may be simpJiRed greatly, as shown in part b above, without undue error. 

Titration and buffer calculations for weak diprotic and triprotic acids are done exactly as shown earlier for weak monoprotic acids. The only new consideration is which Kc or pKa value to use Very simply, we use the appropriate constant that describes the equilibrium between the species we are dealing with. For example, Figure 1-4 shows the titration of a weak diprotic acid with OH (p/ a, = 4, pKo, = 7). The pH at any point along the titration curve is given by ... 

Titration and buffer calculations involving peptides are done exactly as shown earlier for polyprotic acids. We must remember that the amino acid carboxyl groups used in forming the peptide bond are no longer available for titration. The structure of the fully protonated glutamylserylglutamylvaline is shown below. It is assumed that the ct-COOH group retains a pKa of — 2.5... 

Example 3.7. Mixture of Acid and Base (Buffer) Calculate the pH ol a... 

When two dilute solutions are mixed, we assume that their volumes are additive. The volume of the new solution will be 300. mL. Mixing a solution of a weak acid with a solution of its salt does not form any new species. So we have a straightforward buffer calculation. We calculate the number of millimoles (or moles) of each compound and the molarities in the new solution. 

Thus we see that a molarity ratio in the acid-salt Henderson-Hasselbalch equation can be treated as a mole (or millimole) ratio. A similar conclusion can be reached for the base-salt version of the Henderson-Hasselbalch equation or for the or expressions that were used in previous buffer calculations. 

On the AP exam, acid-base questions appear on a regular basis, and buffer calculations are among the most common of those questions to pop up. One of the things you are expected to be able to do is calculate the pH of a buffer solution, and though you may not realize it yet, you have already done this calculation. In the previous example of the common ion effect, when you calculated the pH of the solution made with the 0.30 M acetic acid and the 0.30 M sodium acetate, that was a buffer solution. That is the first type of buffer calculation you are expected to know. The second type of calculation is to determine the effect of adding a strong acid or base to a buffer, and the... 

An industrial chemist studying the effect of pH on bleaching and sterilizing processes prepares several hypochlorite buffers. Calculate the pH of each of the following buffers ... 

Buffers work within 1 pH unit of pKa Buffer calculation... 

The concentration not the number of moles should be used in buffer calculations. 

Binding parameters for potassium hyaluronate solutions in phosphate buffers calculated by Equs. (2), (3), (4), and (5) from data in Ref. 2. 

Before making a buffer, calculate how much strong acid or base will be required. It helps to know if you are going to need 10 mL or 10 drops of reagent before you dispense it. 

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