Validation: questions about buffers and pH Flashcards
What is a buffer solution?
A buffer solution is a solution that is able to resist pH change when small amounts of acid or base is added.
What are the two main components of a buffer solution?
A weak acid and its conjugate base (e.g. CH3COOH and CH3COO-) or a weak base and its conjugate acid (e.g. NH3 and NH4)
How does a buffer solution resist changes in pH when a small amount of acid is added?
The conjugate base in the buffer reacts with the added H+ to neutralise it by forming the weak acid. This prevents a significant pH change.
How does a buffer solution resist changes in pH when a small amount of base is added?
The weak acid in the buffer reacts with the added OH- to neutralise it by forming water and the conjugate base. This prevents a significant pH change.
Why is a mixture of a strong acid/base and its conjugate pair not a buffer?
Because a strong acid/base fully dissociates in water meaning there is no equilibrium to resist pH change
What happens to the pH of a buffer when a strong acid like HCl is added?
The conjugate base reacts with H+ ions to neutralise it, preventing a large pH drop
What happens to the pH of a buffer when a strong base like NaOH is added?
The weak acid reacts with OH- to neutralise it, preventing a large pH increase
Why do biological systems, like blood, need buffers?
Buffers maintain a stable pH so enzymes and proteins can function properly.
What is the main buffer system in human blood?
carbonic acid-bicarbonate buffer system (H2CO3 / HCO3)
Why does adding too much strong acid or base overwhelm a buffer system?
The buffer components run out, so they can no longer neutralise the added acid or base.
How does the blood buffer system respond when the blood becomes too acidic (talk about the buffer system)?
If blood becomes too acidic, bicarbonate reacts with excess H+ ions to form carbonic acid. Carbonic acid then breaks down into CO2 and H2O which is exhaled by the lungs
How does the blood buffer system respond when the blood becomes too basic?
If the blood becomes too basic, carbonic acid dissociated to release H+ ions and counteract the increase in pH
Why is the blood buffer system important for enzyme function in the body?
Enzymes only function within a narrow pH range. If pH changes too much, enzyme structure and function are disrupted.
What is the primary buffer system that regulates ocean pH?
Carbonate buffer system (HCO3 / CO3)
Write the chemical equilibrium equation for the carbonate buffer system in the ocean.
CO2 + H2O ⇌ H2CO3
H2CO3 ⇌ HCO3 + H
HCO3 + H ⇌ CO3 + 2H
How does increasing atmospheric CO₂ affect ocean pH?
More CO₂ dissolves in seawater, forming carbonic acid, which lowers ocean pH (acidification)
What is ocean acidification and why is it a problem?
-Ocean acidification occurs when excess CO₂ dissolves in seawater, forming carbonic acid and lowering pH.
-It reduces carbonate levels, making it harder for marine organisms to form shells and skeletons.
How does the carbonate buffer system help maintain ocean pH?
-When pH drops, carbonate ions (CO3) react with H+ to form bicarbonate, removing excess H⁺.
-When pH rises, bicarbonate (H2CO3) dissociates into carbonate and H+ releasing H⁺ to lower pH.
How does temperature affect the buffering capacity of seawater?
Higher temperatures reduce the solubility of CO₂ in water, weakening the ocean’s ability to buffer pH changes.
