Amphiprotic/Amphoteric Nature of HSO4- & H2PO4 - ChemistryHelp.net

  • Thread starter Thread starter aonin
  • Start date Start date
Click For Summary
SUMMARY

The discussion centers on the amphiprotic nature of HSO4- (hydrogen sulfate) and H2PO4- (dihydrogen phosphate ion). Both ions can accept and donate H+ ions, qualifying them as amphoteric despite being the weak conjugate bases of strong acids, H2SO4 and H3PO4, respectively. The equilibrium for H2SO4 favors ionization into HSO4-, yet HSO4- retains the ability to act as a base. Similarly, H2PO4- is recognized as amphiprotic due to its weaker acid strength (Ka1 ~ 10^-2) compared to H3PO4, allowing it to participate in acid-base reactions.

PREREQUISITES
  • Understanding of acid-base theory, specifically the concepts of amphiprotic and amphoteric substances.
  • Familiarity with the dissociation constants (Ka) of acids, particularly H2SO4 and H3PO4.
  • Knowledge of chemical equilibrium and how it applies to acid-base reactions.
  • Basic chemistry terminology related to ions and their behavior in solutions.
NEXT STEPS
  • Research the specific dissociation constants (Ka) of H2SO4 and H3PO4 to understand their acid strengths.
  • Explore the concept of conjugate acids and bases in the context of the Bronsted-Lowry theory.
  • Study the role of amphiprotic substances in buffer solutions and their applications in chemistry.
  • Investigate other examples of amphoteric ions and their behavior in various chemical reactions.
USEFUL FOR

Chemistry students, educators, and professionals interested in acid-base chemistry, particularly those studying the properties of amphiprotic and amphoteric substances.

aonin
Messages
3
Reaction score
0
Hey guys, on http://www.chemistryhelp.net/basic-chemistry/amphiprotic-substances

I saw that HSO4- (hydrogen sulfate) is a amphiprotic (can accept and donate H+ ions) and therefore acts as a base or acid (amphoteric)

why is this so? Isn't H2SO4 (sulfuric acid) a strong acid and so its equilibrium completely favours the ionisation into HSO4-, therefore HSO4- cannot accept H+ ions to reform back into H2SO4

similarly this happens for H2PO4 (Dihydrogen phosphate ion), so why is it listed as amphiprotic even though H3PO4 is a strong acid and the equilibrium would completely favour ionisation into H2PO4?

So, why are these 2 ions listed as amphoteric even thought they are the weak conjugate bases of strong acids (LB theory)?

Thanks
 
Chemistry news on Phys.org
You shouldn't believe everything you read on the internet, especially when it contradicts your own understanding.
 
aonin said:
I saw that HSO4- (hydrogen sulfate) is a amphiprotic (can accept and donate H+ ions) and therefore acts as a base or acid (amphoteric)

why is this so? Isn't H2SO4 (sulfuric acid) a strong acid and so its equilibrium completely favours the ionisation into HSO4-, therefore HSO4- cannot accept H+ ions to reform back into H2SO4

similarly this happens for H2PO4 (Dihydrogen phosphate ion), so why is it listed as amphiprotic even though H3PO4 is a strong acid and the equilibrium would completely favour ionisation into H2PO4?
H2SO4 has Ka1 ~ 10^6, but H3PO4 has Ka1 of only about 10^-2. So I think that statement is at least somewhat reasonable for H2PO4-.
 

Similar threads

Does Sulfuric acid donate both of it H+ protons?
  • · Replies 7 ·
Replies
7
Views
13K
What is the definition of alkalinity and how is it determined experimentally?
  • · Replies 17 ·
Replies
17
Views
8K
Why Do My Amphoteric Equations Keep Going Wrong?
  • · Replies 6 ·
Replies
6
Views
14K
Does Polyprotic Strong Acid Completely Dissociate in a Net Ionic Equation?
  • · Replies 1 ·
Replies
1
Views
24K
Contribution of the auto dissociation of water
  • · Replies 17 ·
Replies
17
Views
3K
Comparing the pH of H2CO3 and H2SO4 Solutions
  • · Replies 3 ·
Replies
3
Views
4K
Weak Acid Strong Base Reactions: Buffer Solutions
  • · Replies 3 ·
Replies
3
Views
5K
Solubility of PbSO4: Uncovering the Mystery
  • · Replies 14 ·
Replies
14
Views
7K
Solve Ka2 of Sulfuric Acid in Aqueous Solution
  • · Replies 2 ·
Replies
2
Views
16K
How to determine strong acids when reacting with magnesium?
  • · Replies 3 ·
Replies
3
Views
3K