Factors that determine acid strength

In summary, the strength of an acid is determined by the strength and polarity of the bond between hydrogen and the rest of the molecule, as well as the size of the atom or molecule and the stability of the resulting conjugate base. A stronger bond, less polarity, larger size, and more stable conjugate base all contribute to a stronger acid.
  • #1
chemJan2021
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Homework Statement
In these two compounds, the question is to decide more acidic hydrogen.

In No.1, I think the right hydrogen is more acidic because halogen (Fluorine) connects the oxygen next to the hydrogen, pulls the electron and this inductive effect makes the hydrogen more stable.
But the answer is the left hydrogen.
I can’t understand this answer.

In No.2, I also think right hydrogen is more acidic because there is a methyl group on the left side of carbon which is electron donating group and makes the left hydrogen unstable.
But the answer is the left hydrogen.
I think there are the mesomeric effect on both of the hydrogens.
I can’t understand the answer.
Could anyone explain me the reason?
Relevant Equations
I think to solve this kind of more acidic hydrogen, there are these rules below.
1. Compare the element to which a hydrogen bonds.
2. Check if there is the Resonance effect.
3. Check if there is the Inductive effect.
4. The percentage of the S orbitals. SP>SP2>SP3
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  • #2
Both molecules require drawing resonance structures of the conjugate bases to see where the electrons become delocalized.
 
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FAQ: Factors that determine acid strength

What is the definition of acid strength?

Acid strength refers to the ability of an acid to donate a proton (H+) to a base in a chemical reaction. The stronger the acid, the more readily it donates protons.

What are the main factors that determine acid strength?

The main factors that determine acid strength are the polarity of the bond between the hydrogen atom and the rest of the molecule, the stability of the resulting conjugate base, and the strength of the bond between the hydrogen atom and the rest of the molecule.

How does polarity affect acid strength?

The more polar the bond between the hydrogen atom and the rest of the molecule, the more easily the hydrogen atom can be separated and donated as a proton, making the acid stronger.

How does the stability of the conjugate base affect acid strength?

The more stable the resulting conjugate base, the stronger the acid. This is because a stable conjugate base is better able to handle the negative charge that results from donating a proton, making it more likely for the acid to donate a proton.

How does bond strength affect acid strength?

The weaker the bond between the hydrogen atom and the rest of the molecule, the easier it is for the hydrogen atom to be separated and donated as a proton, making the acid stronger. This is because a weaker bond means less energy is required to break the bond and donate the proton.

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