Passage
Within the renal system, two buffers operate to counter the production of excess H⁺ from luminal H₂CO₃. They are located within the tubular lumen, and maintain urinary pH levels between 4.5 and 8.0.The first of these is a phosphate buffer, which serves as the primary buffer for urine because its pK_a is very close to extracellular fluid pH of 7.4. The phosphate buffer operates according to Reaction 1. H₂PO₄⁻ is excreted in urine.
Reaction 1During acidosis when tubular pH is low, the phosphate buffer system becomes saturated. An ammonia buffer system then becomes the primary buffer, and NH₄⁺ is excreted in urine.
Reaction 2Titratable acid (TA) is the total acid in urine, and it can be found using Folin's method. Under normal physiological conditions, TA is approximately equal to the amount of phosphate in urine, which is a product of serum phosphate concentration and glomerular filtration rate. This makes TA a good indicator of kidney function.Folin's method involves back titration of a urine sample to a pH of 7.4 using a strong base. In a typical procedure, potassium oxalate is added to remove calcium from the sample prior to titration with 1.0 M NaOH. The titration continues until the solution reaches a pH of 7.4 (measured by a pH meter) . The amount of base required for the titration can then be used to calculate the amount of H₂PO₄⁻ in the urine sample.
-The chemical process that occurs during acidosis can be replicated in vitro by adding a strong acid to an ammonia buffer solution. How will the pH change in the solution if 1.0 mL of 0.5 M H₂SO₄ is added to a 100 mL solution containing 1 M NH₃ and 1 M NH₄⁺?

Question

Passage
Within the renal system, two buffers operate to counter the production of excess H⁺ from luminal H₂CO₃. They are located within the tubular lumen, and maintain urinary pH levels between 4.5 and 8.0.The first of these is a phosphate buffer, which serves as the primary buffer for urine because its pK_a is very close to extracellular fluid pH of 7.4. The phosphate buffer operates according to Reaction 1. H₂PO₄⁻ is excreted in urine.

Passage Within the renal system, two buffers operate to counter the production of excess H<sup>+</sup> from luminal H<sub>2</sub>CO<sub>3</sub>. They are located within the tubular lumen, and maintain urinary pH levels between 4.5 and 8.0.The first of these is a phosphate buffer, which serves as the primary buffer for urine because its pK<sub>a</sub> is very close to extracellular fluid pH of 7.4. The phosphate buffer operates according to Reaction 1. H<sub>2</sub>PO<sub>4</sub><sup>−</sup> is excreted in urine. <strong>Reaction 1</strong>During acidosis when tubular pH is low, the phosphate buffer system becomes saturated. An ammonia buffer system then becomes the primary buffer, and NH<sub>4</sub><sup>+</sup> is excreted in urine. <strong>Reaction 2</strong>Titratable acid (TA) is the total acid in urine, and it can be found using Folin's method. Under normal physiological conditions, TA is approximately equal to the amount of phosphate in urine, which is a product of serum phosphate concentration and glomerular filtration rate. This makes TA a good indicator of kidney function.Folin's method involves back titration of a urine sample to a pH of 7.4 using a strong base. In a typical procedure, potassium oxalate is added to remove calcium from the sample prior to titration with 1.0 M NaOH. The titration continues until the solution reaches a pH of 7.4 (measured by a pH meter) . The amount of base required for the titration can then be used to calculate the amount of H<sub>2</sub>PO<sub>4</sub><sup>−</sup> in the urine sample. -The chemical process that occurs during acidosis can be replicated in vitro by adding a strong acid to an ammonia buffer solution. How will the pH change in the solution if 1.0 mL of 0.5 M H<sub>2</sub>SO<sub>4</sub> is added to a 100 mL solution containing 1 M NH<sub>3</sub> and 1 M NH<sub>4</sub><sup>+</sup>? A) The pH will increase slightly (<0.1 pH units) because NH<sub>3</sub> and NH<sub>4</sub><sup>+</sup> are a conjugate acid/base pair. B) The pH will decrease slightly (<0.1 pH units) because NH<sub>3</sub> and NH<sub>4</sub><sup>+</sup> act as a buffer. C) The pH will increase significantly (>1.0 pH units) because NH<sub>3</sub> is a strong base. D) The pH will decrease significantly (>1.0 pH units) because H<sub>2</sub>SO<sub>4</sub> is a strong acid.

Reaction 1During acidosis when tubular pH is low, the phosphate buffer system becomes saturated. An ammonia buffer system then becomes the primary buffer, and NH₄⁺ is excreted in urine.

Reaction 2Titratable acid (TA) is the total acid in urine, and it can be found using Folin's method. Under normal physiological conditions, TA is approximately equal to the amount of phosphate in urine, which is a product of serum phosphate concentration and glomerular filtration rate. This makes TA a good indicator of kidney function.Folin's method involves back titration of a urine sample to a pH of 7.4 using a strong base. In a typical procedure, potassium oxalate is added to remove calcium from the sample prior to titration with 1.0 M NaOH. The titration continues until the solution reaches a pH of 7.4 (measured by a pH meter) . The amount of base required for the titration can then be used to calculate the amount of H₂PO₄⁻ in the urine sample.
-The chemical process that occurs during acidosis can be replicated in vitro by adding a strong acid to an ammonia buffer solution. How will the pH change in the solution if 1.0 mL of 0.5 M H₂SO₄ is added to a 100 mL solution containing 1 M NH₃ and 1 M NH₄⁺?

Quizplus · Accepted Answer

11ecba2d_1214_0891_a3bf_1d01fbbf0491_MD0008_00 Buffer systems are comprised of a weak acid and its conjugate base or a weak base and its conjugate acid (often in equal concentrations). In either type of buffer, the mixture provides both acidic and basic species to counteract H⁺ or OH⁻ ions from any strong acid or strong base that is added to the solution. This results in a much smaller change in pH than would have otherwise occurred without the buffer. The buffer species must be in much higher concentration than the amount of strong acid or strong base that is added to the system. If too much of a strong acid or base is added, too much of the weak acid or its conjugate base are consumed, and the buffer no longer resists changes to pH. In the experiment described in the question, a strong acid (H₂SO₄) is added to an ammonia buffer system. The amount of H₂SO₄ added is much less than the concentration of NH₃ and will react with the NH₃ to form NH₄⁺ (a weak acid); therefore, the pH will decrease slightly but the ammonia buffer system will resist a large change in pH. (Choice A) Protons from H₂SO₄ will react with NH₃ (a weak base) to form NH₄⁺ (a weak acid). This will cause the pH of the system to decrease slightly rather than increase. (Choice C) NH₃ is a weak base rather than a strong base (strong bases tend to form OH⁻ ions). The addition of an acid will cause the pH to decrease, not increase. (Choice D) Although the pH will decrease, it will only do so slightly because there is a sufficient concentration of NH₃ in solution to use the H⁺ (added from H₂SO₄) to form NH₄⁺ (a weak acid). Educational objective: Buffer systems counteract H⁺ and OH⁻ ions. When small amounts of a strong acid or base are added to a buffer solution, the solution pH changes only slightly. Adding strong acid causes the pH to decrease slightly whereas adding a strong base causes the pH to increase slightly.

Passage Within the Renal System, Two Buffers Operate to Counter the the Production