Concept explainers
A sodium hydrogen carbonate-sodium carbonate buffer is to be prepared with a pH of 9.40.
(a) What must the
(b) How many moles of sodium hydrogen carbonate must be added to a liter of 0.225 M Na2CO3 to give this pH?
(c) How many grams of sodium carbonate must be added to 475 mL of 0.336 M NaHCO3 to give this pH? (Assume no volume change.)
(d) What volume of 0.200 M NaHCO3 must be added to 735 mL of a 0.139 M solution of Na2CO3 to give this pH? (Assume that volumes are additive.)
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Chapter 14 Solutions
Chemistry: Principles and Reactions
- A buffer is prepared by dissolving 0.0250 mol of sodium nitrite, NaNO2, in 250.0 mL of 0.0410 M nitrous acid, HNO2. Assume no volume change after HNO2 is dissolved. Calculate the pH of this buffer.arrow_forwardKa for formic acid is 1.7 104 at 25C. A buffer is made by mixing 529 mL of 0.465 M formic acid, HCHO2, and 494 mL of 0.524 M sodium formate, NaCHO2. Calculate the pH of this solution at 25C after 110 mL of 0.152 M HCl has been added to this buffer.arrow_forwardAmmonia gas is bubbled into 275 mL of water to make an aqueous solution of ammonia. To prepare a buffer with a pH of 9.56, 15.0 g of NH4Cl are added. How many liters of NH3; at 25C and 0.981 atm should be used to prepare the buffer? Assume no volume changes and ignore the vapor pressure of water.arrow_forward
- Calculate the mass of sodium acetate, NaCH3COO, you should add to 500. mL of a 0.150-M solution of acetic acid, CH3COOH, to buffer a solution at a pH of 4.57.arrow_forwardA buffer is prepared by mixing 525 mL of 0.50 M formic acid, HCHO2, and 475 mL of 0.50 M sodium formate, NaCHO2. Calculate the pH. What would be the pH of 85 mL of the buffer to which 8.6 mL of 0.15 M hydrochloric acid had been added?arrow_forwardCalculate the pH change when 10.0 mL of 0.100-M NaOH is added to 90.0 mL pure water, and compare the pH change with that when the same amount of NaOH solution is added to 90.0 mL of a buffer consisting of 1.00-M NH3 and 1.00-M NH4Cl. Assume that the volumes are additive. Kb of NH3 = 1.8 × 10-5.arrow_forward
- A 25.0-mL sample of hydroxylamine is titrated to the equivalence point with 35.8 mL of 0.150 M HCl. a What was the concentration of the original hydroxylamine solution? b What is the pH at the equivalence point? c Which indicators, bromphenol blue, methyl red, or phenolphthalein, should be used to detect the end point of the titration? Why?arrow_forwardYou want to make a buffer with a pH of 10.00 from NH4+/NH3. (a) What must the [ NH4+ ]/[ NH3 ]ratio be? (b) How many moles of NH4Cl must be added to 465 mL of an aqueous solution of 1.24 M NH3 to give this pH? (c) How many milliliters of 0.236 M NH3 must be added to 2.08 g of NH4Cl to give this pH? (d) What volume of 0.499 M NH3 must be added to 395 mL, of 0.109 M NH4Cl to give this pH?arrow_forwardDetermine the dominant acid-base equilibrium that results when each of the following pairs of solutions is mixed. Indicate the equilibrium by writing 1 for a strong acid, 3 for a weak acid, 4 for an acidic buffer, 7 for a neutral solution, 10 for a basic buffer, 11 for a weak base, and 13 for a strong base. (a) 10.0 mL of 0.15 M NaOH + 15.0 mL of 0.10 M HNO3 (b) 25.0 mL of 0.10 M HCl + 10.0 mL of 0.25 M NH3 (c) 50.0 mL of 0.050 M NaOH + 50.0 mL of 0.10 M NH3 (d) 50.0 mL of 0.10 M NH3 + 50.0 mL of 0.05 M HClarrow_forward
- A chemist needs a buffer with pH 3.50. How many milliliters of pure formic acid (density = 1.220 g/mL) must be added to 375 mL of 0.0857 M NaOH solution to obtain such a buffer?arrow_forwardA good buffer generally contains relatively equal concentrations of weak acid and conjugate base. If you wanted to buffer a solution at pH = 4.00 or pH = 10.00, how would you decide which weak acidconjugate base or weak baseconjugate acid pair to use? The second characteristic of a good buffer is good buffering capacity. What is the capacity of a buffer? How do the following buffers differ in capacity? How do they differ in pH? 0.01 M acetic acid/0.01 M sodium acetate 0.1 M acetic acid/0.1 M sodium acetate 1.0 M acetic acid/1.0 M sodium acetatearrow_forwardWhat is the pH of the solution obtained by titrating 1.30 g of sodium hydrogen sulfate, NaHSO4, dissolved in 50.0 mL of water with 0.175 M sodium hydroxide until the equivalence point is reached? Assume that any volume change due to adding the sodium hydrogen sulfate or to mixing the solutions is negligible.arrow_forward
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