The principles of acids, bases, and buffers are fundamental to pharmaceutical science, governing everything from drug stability to patient comfort. For B.Pharm students, a solid understanding of buffer systems, buffer capacity, and tonicity is essential for formulating safe and effective products, especially parenteral and ophthalmic preparations. This quiz covers the key concepts of these critical topics in pharmaceutical inorganic chemistry.
- A buffer solution is a solution that:
- Reacts completely with any added acid or base.
- Resists a change in pH upon the addition of a small amount of an acid or base.
- Is always neutral with a pH of 7.
- Contains a strong acid and a strong base.
- A typical buffer system is composed of a:
- Strong acid and its conjugate base
- Strong base and its conjugate acid
- Weak acid and its conjugate base
- Strong acid and a strong base
- The Henderson-Hasselbalch equation is used to calculate the:
- pH of a buffer solution
- Molar mass of an acid
- Tonicity of a solution
- Buffer capacity
- Buffer capacity is a measure of the:
- pH of the buffer
- Purity of the buffer components
- Magnitude of resistance to a pH change
- Temperature stability of the buffer
- A solution that has the same osmotic pressure as body fluids is called:
- Hypotonic
- Hypertonic
- Isotonic
- Apolar
- Pharmaceutical buffers are most critical in which of the following formulations?
- Oral tablets
- Topical powders
- Parenteral and ophthalmic solutions
- Hard gelatin capsules
- An agent that increases the acidity of gastric fluid is known as a(n):
- Antacid
- Buffer
- Acidifier
- Cathartic
- The Henderson-Hasselbalch equation is written as:
- pH = pKa + log([Acid]/[Salt])
- pH = pKa + log([Salt]/[Acid])
- pKa = pH + log([Salt]/[Acid])
- pH = pKa – log([Salt]/[Acid])
- A buffer has its maximum buffer capacity when:
- pH = 7
- [Salt] > [Acid]
- [Acid] > [Salt]
- pH = pKa (i.e., [Salt] = [Acid])
- Tonicity is a property of a solution that depends on the:
- Concentration of solute particles
- Color of the solution
- Temperature of the solution
- Viscosity of the solution
- An example of a pharmaceutical acidifier is:
- Sodium bicarbonate
- Aluminum hydroxide
- Dilute Hydrochloric Acid
- Magnesium hydroxide
- Which of the following is a common property of an ideal antacid?
- It should be a strong systemic alkali.
- It should cause constipation or diarrhea.
- It should not be absorbed systemically.
- It should have a slow onset of action.
- A solution that causes red blood cells to shrink (crenation) is:
- Isotonic
- Hypotonic
- Hypertonic
- Neutral
- The pH of a buffer solution depends on the:
- pKa of the weak acid
- Ratio of the salt to acid concentration
- Both A and B
- Buffer capacity
- Which of the following is a common buffer system used in pharmaceutical preparations?
- Phosphate buffer system
- Hydrochloric acid system
- Sodium hydroxide system
- Sulfate buffer system
- The main purpose of a “buffered isotonic solution” is to:
- Increase the drug’s potency.
- Reduce pain and irritation upon administration and maintain drug stability.
- Make the solution colored.
- Speed up the drug’s metabolism.
- Which of the following is a systemic antacid?
- Aluminum hydroxide
- Magnesium carbonate
- Calcium carbonate
- Sodium bicarbonate
- A solution that causes red blood cells to swell and burst (hemolysis) is:
- Isotonic
- Hypertonic
- Hypotonic
- A buffer
- Ammonium chloride is used as a systemic:
- Antacid
- Acidifier
- Buffer
- Antidote
- Buffer capacity is highest when the concentration of the buffer components is:
- Low
- High
- Equal to zero
- Variable
- Which of the following is NOT a method for adjusting the tonicity of a solution?
- Sodium chloride equivalent method
- Freezing point depression method
- White-Vincent method
- Henderson-Hasselbalch method
- The combination of aluminum hydroxide and magnesium hydroxide in antacids is used to:
- Increase the potency
- Counteract the side effects of each other (constipation and diarrhea)
- Provide a systemic effect
- Decrease the onset of action
- The physiological pH of blood plasma is maintained at approximately:
- 7.0
- 6.8
- 7.4
- 8.0
- Why are buffers important for the stability of some drugs?
- They prevent the drug from dissolving.
- They maintain a pH at which the drug is most stable.
- They increase the molecular weight of the drug.
- They act as a preservative.
- The measurement of tonicity is often based on the comparison of a solution’s ______ with that of blood.
- Color
- pH
- Freezing point depression
- Viscosity
- Which of the following is a non-systemic antacid?
- Sodium bicarbonate
- Magnesium hydroxide
- Sodium citrate
- Potassium bicarbonate
- A common substance used to make an ophthalmic solution isotonic is:
- Sodium chloride
- Boric acid
- Dextrose
- All of the above
- An acid can be defined as a substance that:
- Accepts a proton
- Donates a proton
- Accepts an electron pair
- Both B and C
- What happens to the pH of a buffer solution when a small amount of strong acid is added?
- It increases significantly.
- It decreases significantly.
- It remains relatively constant.
- It becomes neutral.
- The pKa of a weak acid is the pH at which the acid is:
- 100% ionized
- 100% unionized
- 50% ionized and 50% unionized
- Completely neutralized
- Which of the following is a common side effect of aluminum-containing antacids?
- Diarrhea
- Systemic alkalosis
- Constipation
- Flatulence
- A base can be defined as a substance that:
- Donates a proton
- Accepts a proton
- Donates an electron pair
- Is insoluble in water
- The main buffer system in the blood is the:
- Phosphate buffer system
- Protein buffer system
- Carbonic acid-bicarbonate buffer system
- Acetate buffer system
- If a buffer is prepared from a weak base (B) and its salt (BH⁺Cl⁻), the relevant equation would be:
- pH = pKa + log([Salt]/[Acid])
- pOH = pKb + log([Salt]/[Base])
- pH = pKb – log([Salt]/[Base])
- pOH = pKa + log([Base]/[Salt])
- The primary reason for making parenteral solutions isotonic is to:
- Prevent hemolysis or crenation of red blood cells.
- Improve the drug’s taste.
- Increase the drug’s shelf life.
- Make the solution easier to inject.
- Which of the following is a common side effect of magnesium-containing antacids?
- Constipation
- Diarrhea (laxative effect)
- Acid rebound
- Systemic alkalosis
- A good buffer should have a pKa that is:
- Much higher than the desired pH
- Much lower than the desired pH
- Close to the desired pH
- Exactly 7
- The term ‘tonicity’ is a measure of a solution’s:
- Acidity
- Basicity
- Effective osmotic pressure gradient
- Viscosity
- Which of these is a common pharmaceutical buffer pair?
- Acetic acid and sodium acetate
- Boric acid and sodium borate
- Sodium phosphate monobasic and sodium phosphate dibasic
- All of the above
- “Acid rebound” is a potential issue with which antacid?
- Aluminum hydroxide
- Magnesium hydroxide
- Calcium carbonate
- Simethicone
- The stability of a buffer solution depends on its:
- Resistance to temperature changes
- Resistance to dilution
- Resistance to microbial growth
- All of the above
- A pharmaceutical acidifier can be used to:
- Neutralize excess stomach acid
- Correct systemic alkalosis
- Act as a laxative
- Prevent dental caries
- Which component of a buffer system neutralizes added alkali (base)?
- The weak acid component
- The weak base component
- The salt component
- The conjugate acid component
- An ideal pharmaceutical buffer should be:
- Non-toxic
- Biologically compatible
- Stable
- All of the above
- Which of the following is NOT an ideal property of an antacid?
- Should be rapid and long-acting.
- Should buffer in the pH range of 3-6.
- Should cause systemic alkalosis.
- Should not cause constipation or diarrhea.
- What is the function of the salt in a weak acid buffer?
- It acts as a source of the conjugate base.
- It neutralizes the weak acid.
- It acts as a preservative.
- It adjusts the tonicity.
- The choice of buffer for a pharmaceutical formulation depends mainly on the:
- Desired pH and required buffer capacity
- Cost of the buffer components
- Color of the buffer
- Taste of the buffer
- Which component of a buffer system neutralizes added acid?
- The weak acid component
- The conjugate base (salt) component
- Water
- The solvent
- A 0.9% w/v solution of sodium chloride is considered:
- Isotonic
- Hypotonic
- Hypertonic
- A buffer
- The main role of buffers in pharmaceutical systems is to:
- Increase drug solubility
- Maintain a specific pH to ensure stability and efficacy
- Act as the active pharmaceutical ingredient
- Provide a sweet taste to the formulation
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
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