An acid-base indicator, HIn, dissociates according to the reaction shown in an aqueous solution. K₁. Hin HIn(aq) The protonated form of the indicator, HIn, has a molar absorptivity of 3045 M-¹-cm-¹ and the deprotonated form, In, has molar absorptivity of 20860 M-¹-cm-¹ at 440 nm. The pH of a solution containing a mixture of HIn and In is adjusted to The total concentration of HIn and In is 0.000177 M. The absorbance of this solution was measured at 440 nm in a 1.00 c cuvet and was determined to be 0.770. Calculate pK, for HIn. In (aq) + H+ (aq)

An acid-base indicator, HIn, dissociates according to the reaction shown in an aqueous solution. K₁. Hin HIn(aq) The protonated form of the indicator, HIn, has a molar absorptivity of 3045 M-¹-cm-¹ and the deprotonated form, In, has molar absorptivity of 20860 M-¹-cm-¹ at 440 nm. The pH of a solution containing a mixture of HIn and In is adjusted to The total concentration of HIn and In is 0.000177 M. The absorbance of this solution was measured at 440 nm in a 1.00 c cuvet and was determined to be 0.770. Calculate pK, for HIn. In (aq) + H+ (aq)

Chemistry: An Atoms First Approach

2nd Edition

ISBN:9781305079243

Author:Steven S. Zumdahl, Susan A. Zumdahl

Publisher:Steven S. Zumdahl, Susan A. Zumdahl

Chapter14: Acid- Base Equilibria

Section: Chapter Questions

Problem 8ALQ: You have a solution of the weak acid HA and add some of the salt NaA to it. What are the major...

See similar textbooks

Similar questions

Amino acids are an important group of compounds. At low pH, both the carboxylic acid group (CO2H) and the amine group (NHR) are protonated. However, as the pH of the solution increases (say, by adding base), the carboxylic acid proton is removed, usually at a pH between 2 and 3. In a middle range of pHs, therefore, the amine group is protonated, but the carboxylic acid group has lost the proton. (This is called a zwitterion.) At more basic pH values, the amine proton is dissociated. What is the pH of a 0.20 M solution of alanine hydrochloride, [NH3CHCH3CO2H]Cl?
Sketch a titration curve for the titration of potassium hydroxide with HCl, both 0.100 M. Identify three regions in which a particular chemical species or system dominates the acid-base equilibria.
Given three acid-base indicatorsâ€”methyl orange (end point at pH 4), bromthymol blue (end point at pH 7), and phenolphthalein (end point at pH 9)â€”which would you select for the following acid-base titrations? (a) perchloric acid with an aqueous solution of ammonia (b) nitrous acid with lithium hydroxide (c) hydrobromic acid with strontium hydroxide (d) sodium fluoride with nitric acid
The simplest amino acid is glycine, H2NCH2CO2H. The common feature of amino acids is that they contain the functional groups: an amine group, -NH2, and a carboxylic acid group, -CO2H. An amino acid can function as either an acid or a base. For glycine, the acid strength of the carboxyl group is about the same as that of acetic acid. CH3CO2H, and the base strength of the amino group is slightly greater than that of ammonia, NH3. (a) Write the Lewis structures of the ions that form when glycine is dissolved in 1 M HCl and in 1 M KOH. (b) Write the Lewis structure of glycine when this amino acid is dissolved in water. (Hint: Consider the relative base strengths of the -NH2 and -CO2- groups.)
. How is the strength of an acid related to the fact that a competition for protons exists in aqueous solution between water molecules and the anion of the acid?
The acid-base indicator "Thymol Blue" has two transition ranges as listed below (with the corresponding acid dissociation constants): 7. Ka AcidColour BaseColour Thymol Blue 1 Thymol Blue 2 2.24 x 102 Red Yellow 1.26 x 10 Yellow Blue What colour would you expect it to be at the following pH values? Briefly justify your answers. (a) (b) (c) (d) 0.9 5.2 7.8 10.7
B represents an acid-base indicator and behaves like a base. Its dissociation equilibrium in an aqueous solution can be written as: B(ac) + H2O(l) <-> +BH(ac) + OH(ac) If B (ac) is yellow +BH is red. Using Le Châtelier's principle, predict the color of the indicator by adding a few drops of the indicator to an aqueous solution of HCl and an aqueous solution of NaOH. Write the corresponding chemical reactions.
Determine the pH of the resulting solution when the following two solutions are mixed: 50.0 mL of 0.500 M HNO2 and 30.0 mL of 0.200 M Ca(OH).. The value of Ka for HNO2 is 6.8 × 104. 1 3 4 NEXT > Use the table below to determine the moles of reactant and product after the reaction of the acid and base. You can ignore the amount of liquid water in the reaction. HNO:(aq) ОН (аq) H:O(1) NO: (aq) + + Before (mol) Change (mol) After (mol) 5 RESET 0.500 0.200 +x -X 0.500 + x 0.500 - x 0.200 + x 0.200 - x 0.0060 -0.0060 0.0120 -0.0120 0.0250 -0.0250 0.0190 -0.0190 0.0130 -0.0130
Instrumental acid-base titrations use a pH meter to monitor the changes in pH and volume. The equivalence point is found from the volume at which the curve has the steepest slope.(a) Use Figure to calculate the slope pH/V for all pairs of adjacent points and to calculate the average volume (V(avg)) for each interval.(b) Plot ΔpH/ΔV vs. V(avg) to find the steepest slope, and thus the volume at the equivalence point. (For example, the first pair of points gives ΔpH= 0.22, ΔV=10.00 mL; hence, ΔpH/ΔV=0.022 mL⁻¹, and V(avg)=5.00 mL.)
Determine the pH during the titration of 57.0 mL of 0.347 M nitrous acid (K₂ = 4.5x10-4) by 0.347 M NaOH at the following points. (Assume the titration is done at 25 °C.) (a) Before the addition of any NaOH (b) After the addition of 14.0 mL of NaOH (c) At the half-equivalence point (the titration midpoint) (d) At the equivalence point (e) After the addition of 85.5 mL of NaOH
The indicator meta-cresol purple is an acid with a Ka of 3.1 ✕ 10−2. In a 2.2 ✕ 10−4 M solution, it is red in acid and yellow in base. Calculate the pH range over which it goes from 10.% ionized (red) to 90.% ionized (yellow). (a) pH at 10.% ionized
16,2 Describe the effect on pH (increase, decrease, or no change) that results from each of the following addi- tions: (a) potassium acetate to an acetic acid solu- tion; (b) ammonium nitrate to an ammonia solution; (c) sodium formate (HCOONA) to a formic acid (HCOOH) solution; (d) potassium chloride to a hy- drochloric acid solution; (e) barium iodide to a hy- droiodic acid solution.