Buffers calculating the

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. 

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. 

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

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 ... 

Relationships Involving Carboxylic Acids the box accompanying Section 19 4) to calculate the CH3NH3 /CH3NH2 ratio in water buffered at pH 7... 

As in Example 6.13, the Henderson-Hasselbalch equation provides a simple way to calculate the pH of a buffer and to determine the change in pH upon adding a strong acid or strong base. 

Suppose you need to prepare a buffer with a pH of 9.36. Using the Henderson-Hasselbalch equation, you calculate the amounts of acetic acid and sodium acetate needed and prepare the buffer. When you measure the pH, however, you find that it is 9.25. If you have been careful in your calculations and measurements, what can account for the difference between the obtained and expected pHs In this section, we will examine an important limitation to our use of equilibrium constants and learn how this limitation can be corrected. 

Calculate the solubility of CaF2 in a solution buffered to a pH of 7.00. Use a ladder diagram to help simplify the calculations. How would your approach to this problem change if the pH is buffered to 2.00 What is the solubility of CaF2 at this pH ... 

A sample contains a weak acid analyte, HA, and a weak acid interferent, HB. The acid dissociation constants and partition coefficients for the weak acids are as follows Ra.HA = 1.0 X 10 Ra HB = 1.0 X f0 , RpjHA D,HB 500. (a) Calculate the extraction efficiency for HA and HB when 50.0 mF of sampk buffered to a pH of 7.0, is extracted with 50.0 mF of the organic solvent, (b) Which phase is enriched in the analyte (c) What are the recoveries for the analyte and interferent in this phase (d) What is the separation factor (e) A quantitative analysis is conducted on the contents of the phase enriched in analyte. What is the expected relative erroi if the selectivity coefficient, Rha.hb> is 0.500 and the initial ratio ofHB/HA was lO.O ... 

Any solution containing comparable amounts of a weak acid, HA, and its conjugate weak base, A-, is a buffer. As we learned in Chapter 6, we can calculate the pH of a buffer using the Henderson-Hasselbalch equation. 

The following data are for the hydrolysis of cinnamic anhydride in (2-amino-2-hydroxymethyl-1,3-propane diol buffers. Extrapolate them to zero buffer concentration, and, together with data from Problem 9, plot the pH-rate profile. Determine the order with respect to hydroxide, and calculate the rate constant for hydrolysis. 

These rate constants are for the hydrolysis of cinnamic anhydride in carbonate buffer, pH 8.45, total buffer concentration 0.024 M, in the presence of the catalysts pyridine, A -methylimidazole (NMIM), or 4-dimethylaminopyridine (DMAP). In the absence of added catalyst, but the presence of buffer, the rate constant was 0.005 24 s . You may assume that only the conjugate base form of each catalyst is catalytically effective. Calculate the catalytic rate constant for the three catalysts. What is the catalytic power of NMIM and of DMAP relative to pyridine ... 

Apparent partition coefficient (logZ)) at an ionic strength of / = 0.02M, log P value of the neutral microspecies and the acidic dissociation constant of 5 was calculated (97ANC4143). The distribution coefficient of 5 was determined between 1-octanol and universal buffer in the pH range 3-10 at a... 

The buffer capacity of the pit fluid is equal to the change in alkalinity of the system per unit change of pH. Figure 4-491 shows the buffer intensity (capacity) of a 0.1 M carbonate pit fluid. Calculating the initial buffer capacity of the pit fluid allows for prediction of the pH change upon introduction of live acid and also any addition of buffer, such as sodium bicarbonate, required to neutralize the excess hydrogen ions. 

This relation, known as the Henderson-Hasselbalch equation, is often used in biology and biochemistry to calculate the pH of buffers. Historically, it was Henderson who discovered Equation 14.1 in 1908. Hasselbalch put it in logarithmic form eight years later. 

Equation 141 is a completely general equation, applicable to all buffer systems. The calculation of [H+]—and hence pH—can be simplified if you keep two points in mind. 

Consider the buffer described in Example 14.1, where nmac = Lac = 1.00 mol (Kg HLac = 1.4 X 10-4). You will recall that in this buffer die pH is 3.85. Calculate the pH after addition of... 

It. A buffer is prepared by dissolving 0.0250 mol of sodium nitrite, NaN02, in 250.0 mL of 0.0410 M nitrous acid, HN02. Assume no volume change after HN02 is dissolved. Calculate the pH of this buffer. 

Calculate the solubility (g/100 mL) of iron(n) hydroxide in buffered solutions with the following pH s. 

In the Taylor-Prandtl modification of the theory of heat transfer to a turbulent fluid, it was assumed that the heat passed directly from the turbulent fluid to the laminar sublayer and the existence of the buffer layer was neglected. It was therefore possible to apply the simple theory for the boundary layer in order to calculate the heat transfer. In most cases, the results so obtained are sufficiently accurate, but errors become significant when the relations are used to calculate heat transfer to liquids of high viscosities. A more accurate expression can be obtained if the temperature difference across the buffer layer is taken into account. The exact conditions in the buffer layer are difficult to define and any mathematical treatment of the problem involves a number of assumptions. However, the conditions close to the surface over which fluid is flowing can be calculated approximately using the universal velocity profile,(10)... 

In the buffer zone the value of d +/dy+ is twice this value. Obtain an expression for the eddy kinematic viscosity E in terms of the kinematic viscosity (pt/p) and y+. On the assumption that the eddy thermal diffusivity Eh and the eddy kinematic viscosity E are equal, calculate the value of the temperature gradient in a liquid flowing over the surface at y =15 (which lies within the buffer layer) for a surface heat flux of 1000 W/m The liquid has a Prandtl number of 7 and a thermal conductivity of 0.62 W/m K. 

---