Charged or neutral

[705676154]

For a weak base how can I tell if the predominant species at a certain pH is charged, neutral, or unknown?

[katrinahuwang_1L]

You can determine whether or not the predominant species at a certain pH is charged, neutral, or unknown when comparing it to the pKa of the conjugate acid.
When the pH of the solution is equal to the pKa of the conjugate acid (BH+), this means that there are equal amounts of the weak base (B) and the the conjugate acid (BH+) in solution.

When pH < pKa, the charged, protonated species of BH+ will become more predominant in solution. When pH > pKa, the neutral, deprotonated species of B will become more predominant in solution.

[sadiebrebes]

You can determine whether or not the predominant species at a certain pH is charged, neutral, or unknown when comparing it to the pKa of the conjugate acid.
When the pH of the solution is equal to the pKa of the conjugate acid (BH+), this means that there are equal amounts of the weak base (B) and the the conjugate acid (BH+) in solution.

When pH < pKa, the charged, protonated species of BH+ will become more predominant in solution. When pH > pKa, the neutral, deprotonated species of B will become more predominant in solution.

How do you calculate the pka of only the conjugate acid? What are the steps?

[Jocelyn Chin 1K]

You can determine whether or not the predominant species at a certain pH is charged, neutral, or unknown when comparing it to the pKa of the conjugate acid.
When the pH of the solution is equal to the pKa of the conjugate acid (BH+), this means that there are equal amounts of the weak base (B) and the the conjugate acid (BH+) in solution.

When pH < pKa, the charged, protonated species of BH+ will become more predominant in solution. When pH > pKa, the neutral, deprotonated species of B will become more predominant in solution.

How do you calculate the pka of only the conjugate acid? What are the steps?

The equation for the conjugate acid is BH+ + H2O--> B + H3O+. Ka is the equilibrium constant for this equation, so [B][H3O+]/[BH+], and pKa would be -log of this Ka.

[cnyland]

If the pH is greater than the pKa, the deprotonated species is dominant, so it would be neutral
If the ph is less than the pKa, the protonated species is dominant, so it would be charged

[405566265]

if there is a large Ka or Kb, then this means that the acid or base is strong and dissociates more. you can find the percent ionized to determine whether the dominant species is neutral or charged. if for example, more than 50% of the compound becomes ionized, then the dominant species is charged.

[Ginny Ghang 1B]

If pH is equal to the pKa of the conjugate acid, there are equal amounts of the weak base and the conjugate acid. If pH is below pKa, there will be more of the charged BH+ in the solution. If pH is above the pKa, there will be more of the neutral B species in the solution.

[Ally Mosher]

If the pH is greater than the pKa, the deprotonated species is dominant, so it would be neutral
If the ph is less than the pKa, the protonated species is dominant, so it would be charged

Thank you, this helped alot.

[Amanda Jacobs 2B]

You can tell if it is charged or neutral by seeing if the pKa is smaller or larger than the pH. And if they are equal then there is an equal amount of charged and neutral molecules. If pKa is greater then it's charged, if pKA is smaller then it's neutral.

[Arden Napoli 1E]

Hi,

To determine if the predominant species is charged or neutral is dependent on the relationship between pKa and pH. If the pKa is greater than the pH, then the predominant species is charged. If the pKa and the pH are equal, then the predominant species is neutral.