Buffer Capacity and pH Relationships

The video tutorial explains the concept of buffer capacity, which measures a buffer's ability to resist pH changes when strong acids or bases are added. It discusses how buffer capacity is quantified and represented graphically, emphasizing the importance of equal concentrations of weak acid and conjugate base. The tutorial provides guidelines for selecting appropriate buffer components based on target pH and illustrates these concepts with an example involving acetic acid and sodium hydroxide.

What is the primary role of a buffer in a solution?

• To resist changes in pH when acids or bases are added

• To increase the pH of the solution

• To neutralize the solution completely

• To decrease the pH of the solution

How is buffer capacity quantitatively defined?

• The amount of water needed to dilute the buffer

• The temperature at which the buffer is most effective

• The amount of strong acid or base needed to change the pH by one unit

• The concentration of the buffer solution

What is the significance of the buffer region in a pH graph?

• It shows where the buffer is least effective

• It indicates the pH range where the buffer is most effective

• It marks the point of buffer breakdown

• It is irrelevant to buffer capacity

What happens to buffer capacity when the concentrations of weak acid and conjugate base are not equal?

• Buffer capacity remains the same

• Buffer capacity decreases

• Buffer capacity becomes infinite

• Buffer capacity increases

What is the ideal pH range for a buffer relative to the pKa of the conjugate acid?

• Exactly at the pKa

• Irrelevant to the pKa

• Within plus or minus one pH unit

• Within plus or minus two pH units

What is the effect of increasing the concentration of a buffer's components?

• Makes the buffer more acidic

• Decreases buffer capacity

• Increases buffer capacity

• Has no effect on buffer capacity

Which pKa value should a conjugate acid have for a buffer with a target pH less than 7?

• Less than 7

• Exactly 7

• Greater than 7

• Irrelevant to the target pH

What is the relationship between the pKa of HB+ and the target pH for a buffer with a pH greater than 7?

• pKa should be greater than 7

• pKa should be less than 7

• pKa is irrelevant

• pKa should be exactly 7

In a titration curve, what indicates that a buffer is no longer effective?

• The curve becomes a straight line

• The curve shows no change

• The curve becomes extremely steep

• The curve becomes flat

What happens when the ratio of HA to A- is less than 0.1?

• The buffer becomes more effective

• The buffer's pH remains constant

• The buffer breaks down

• The buffer becomes more concentrated