Answer:
Explanation:
I can certainly describe the titration curves and point out the equivalence and half-equivalence points for each of these scenarios. However, please note that I can't provide actual sketches, but I can describe them in text.
Weak Base Added to Strong Acid:
Initially, the pH is low (acidic) because of the excess strong acid.
As you add the weak base, the pH starts to rise gradually.
The equivalence point is reached when the moles of weak base added are equal to the moles of strong acid initially present. At this point, the pH will be neutral (around 7).
The half-equivalence point occurs when half of the moles of strong acid have reacted with the weak base. The pH at this point is equal to the pKa of the weak base.
Strong Acid Added to Weak Base:
Initially, the pH is high (basic) because of the excess weak base.
As you add the strong acid, the pH decreases gradually.
The equivalence point is reached when the moles of strong acid added are equal to the moles of weak base initially present. At this point, the pH will be neutral (around 7).
The half-equivalence point occurs when half of the moles of weak base have reacted with the strong acid. The pH at this point is equal to the pKa of the weak base.
Weak Acid Added to Strong Base:
Initially, the pH is high (basic) because of the excess strong base.
As you add the weak acid, the pH starts to decrease gradually.
The equivalence point is reached when the moles of strong base added are equal to the moles of weak acid initially present. At this point, the pH will be neutral (around 7).
The half-equivalence point occurs when half of the moles of strong base have reacted with the weak acid. The pH at this point is equal to the pKa of the weak acid.
Strong Base Added to Weak Acid:
Initially, the pH is low (acidic) because of the excess weak acid.
As you add the strong base, the pH increases gradually.
The equivalence point is reached when the moles of strong base added are equal to the moles of weak acid initially present. At this point, the pH will be neutral (around 7).
The half-equivalence point occurs when half of the moles of weak acid have reacted with the strong base. The pH at this point is equal to the pKa of the weak acid.
These curves are typical for acid-base titrations and are essential for determining the concentration of an unknown solution or the dissociation constant (Ka or Kb) of a weak acid or base. The key points to remember are the changes in pH as you approach and reach the equivalence point and the pH at the half-equivalence point, which relates to the pKa or pKb of the weak acid or base involved in the titration.