Amphoteric Compounds: Ka of H2PO4 & HS Reaction Explained

  • Thread starter Seinfeld4
  • Start date
  • Tags
    Compounds
In summary, the reaction between H2PO4 and HS can be represented by the formula H2PO4 + HS <--> HPO4 + H2S. H2PO4 acts as the acid in this reaction due to its higher Ka value, donating a proton to HS which acts as the base. It is important to consider charges in the formula.
  • #1
Seinfeld4
21
0

Homework Statement



The Ka of H2PO4 is 6.3 * 10^-8. The Ka of HS is 1.3 * 10^-13. Write a formula for the reaction of these substances and explain your results. Both are amphoteric.

The Attempt at a Solution



The formula is:

H2PO4 + HS <--> HPO4 + H2S

I figured that the H2PO4 will act more like the acid in this particular situation because it has a higher value of Ka. So, H2PO4 will donate a proton while HS will receive a proton.

Is this the correct train of thought?

Thanks.
 
Physics news on Phys.org
  • #2
Seinfeld4 said:
Is this the correct train of thought?

Yes. Just don't ignore charges - use [noparse]-[/noparse] to get -.
 

1. What is an amphoteric compound?

An amphoteric compound is a substance that can act as both an acid and a base, meaning it can donate or accept protons (H+ ions) depending on the reaction it is involved in.

2. What is the Ka of H2PO4?

The Ka of H2PO4 (dihydrogen phosphate) is the acid dissociation constant, which measures the strength of an acid in solution. The specific Ka value for H2PO4 is dependent on the concentration of the acid and the solvent in which it is dissolved.

3. How is the Ka of H2PO4 determined?

The Ka of H2PO4 can be determined experimentally by measuring the concentrations of the acid and its conjugate base (HPO4) at equilibrium and using the equilibrium constant expression: Ka = [H+][HPO4-]/[H2PO4-]. It can also be calculated using mathematical equations based on the known dissociation constants of H3PO4 (phosphoric acid) and HPO4 (monohydrogen phosphate).

4. What is the HS reaction and how does it relate to amphoteric compounds?

The HS (hydrogen sulfide) reaction refers to the ability of an amphoteric compound, such as H2PO4, to react with both acids and bases. In acidic conditions, H2PO4 acts as a base and accepts a proton to form H3PO4. In basic conditions, it acts as an acid and donates a proton to form HPO4.

5. How do amphoteric compounds play a role in chemical reactions?

Amphoteric compounds are important in chemical reactions because they can act as a buffer, helping to maintain a stable pH in a solution. They can also act as intermediates in various chemical reactions, facilitating the transfer of protons between other acids and bases. Additionally, amphoteric compounds can participate in redox reactions, where they gain or lose electrons to form different compounds.

Similar threads

  • Biology and Chemistry Homework Help
Replies
4
Views
7K
  • Biology and Chemistry Homework Help
Replies
1
Views
5K
Replies
2
Views
13K
Replies
2
Views
7K
  • Biology and Chemistry Homework Help
Replies
3
Views
2K
  • Biology and Chemistry Homework Help
Replies
2
Views
2K
  • Other Physics Topics
Replies
0
Views
674
Replies
32
Views
7K
Back
Top