Concept explainers
A buffer contains
a.
b. Both
c. Both
d.
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INTRODUCTORY CHEMISTRY-W/SEL.SOLN.MAN.
- Enough water is added to the buffer in Question 29 to make the total volume 10.0 L. Calculate (a) the pH of the buffer. (b) the pH of the buffer after the addition of 0.0500 mol of HCl to 0.600 L of diluted buffer. (c) the pH of the buffer after the addition of 0.0500 mol of NaOH to 0.600 L of diluted buffer. (d) Compare your answers to Question 29(a)-(c) with your answers to (a)-(c) in this problem. (e) Comment on the effect of dilution on the pH of a buffer and on its buffer capacity.arrow_forwardA buffer is composed of formic acid and its conjugate base, the formate ion. (a) What is the pH of a solution that has a formic acid concentration of 0.050 M and a sodium formate concentration of 0.035 M? (b) What must the ratio of acid to conjugate base be to have a pH value 0.50 units higher than the value calculated in part (a)?arrow_forwardIndicate whether each of the following statements is true or false. If the statement is false, restate it to make it true. (a) The formate ion (CHO2-) concentration in 0.10 M HCHO2 is the same as in 0.10 M NaCHO2. (b) A buffer can be destroyed by adding too much strong acid. (c) A buffer can be made up by any combination of weak acid and weak base. (d) Because Ka for HCO3- is4.71011, Kb for HCO3- is2.1104.arrow_forward
- 1. Which choice would be a good buffer solution? 0.20 M KCH3CO2 and 0.20 M CH3CO2H 0.20 M HCl and 0.10 M KOH 0.20 M CH3CO2H and 0.10 M HCO2H 0.10 HCl and 0.010 M KClarrow_forwardAn aqueous solution contains dissolved C6H5NH3Cl and C6H5NH2. The concentration of C6H5NH2 is 0.50 M and pH is 4.20. a. Calculate the concentration of C6H5NH3+ in this buffer solution. b. Calculate the pH after 4.0 g NaOH(s) is added to 1.0 L of this solution. (Neglect any volume change.)arrow_forwardA friend asks the following: Consider a buffered solution made up of the weak acid HA and its salt NaA. If a strong base like NaOH is added, the HA reacts with the OH to form A. Thus the amount of acid (HA) is decreased, and the amount of base (A) is increased. Analogously, adding HCI to the buffered solution forms more of the acid (HA) by reacting with the base (A). Thus how can we claim that a buffered solution resists changes in the pH of the solution? How would you explain buffering to this friend?arrow_forward
- Briefly describe how a buffer solution can control the pH of a solution when strong acid is added and when strong base is added. Use NH3/NH4Cl as an example of a buffer and HCl and NaOH as the strong acid and strong base.arrow_forwardIdentify each pair that could form a buffer. (a) NaOH and NaCl (b) NaOH and NH3 (c) Na3PO4 and Na2HPO4arrow_forwardA buffer solution was prepared by adding 4.95 g sodium acetate to 250. mL of 0.150-M acetic acid. What ions and molecules are present in the solution? List them in order of decreasing concentration. Calculate the pH of the buffer solution. Calculate the pH of 100. mL of the buffer solution if you add 80. mg NaOH. (Assume negligible change in volume.) Write a net ionic equation for the reaction that occurs to change the pH.arrow_forward
- Enough water is added to the buffer in Question 30 to make the total volume 5.00 L. (a) Calculate the pH of the buffer. (b) Calculate the pH of the buffer after adding 0.0250 mol of HCl to 0.376 L of the buffer. (c) Calculate the pH of the buffer after adding 0.0250 mol of KOH to 0.376 L of the buffer. (d) Compare your answers to Question 30 (a-c) with your answers to (a-c) of this problem. (e) Comment on the effect of dilution on the pH of a buffer and on its buffer capacity. Âarrow_forwardA 30.0-mL sample of 0.05 M HClO is titrated by a 0.0250 M KOH solution Ka for HClO is 3.5 108. Calculate a the pH when no base has been added; b the pH when 30.00 mL of the base has been added; c the pH at the equivalence point; d the pH when an additional 4.00 mL of the KOH solution has been added beyond the equivalence point.arrow_forwardEach symbol in the box below represents a mole of a component in one liter of a buffer solution; represents the anion (X-), = the weak acid (HX), = H+, and =OH. Water molecules and the few H+ and OH- ions from the dissociation of HX and X- are not shown. The box contains 10 mol of a weak acid, , in a liter of solution. Show what happens upon (a) the addition of 2 mol of OH- (2 ). (b) the addition of 5 mol of OH- (5 ). (c) the addition of 10 mol of OH- (10 ). (d) the addition of 12 mol of OH- (12 ). Which addition (a)-(d) represents neutralization halfway to the equivalence point?arrow_forward
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