Determine the direction of the following reaction from the relative strengths of acids and bases:

H2S(aq) + C2H3O2-(aq) yields Hc2H3O2(aq) + HS-(aq)

The book says this will favor the reactants. I'm confused...shouldn't this be neutral because both reactants and products have weak acids and bases?

But H2S is a weaker acid than HC2H3O2.

http://books.google.com/books?id=opdKO6Ee4m4C&pg=PA632&lpg=PA632&dq=how+to+determine+direction+reaction+when+comparing+strengths&source=bl&ots=BpKLNbCEXE&sig=F9lSLYAHf-ffEX13ixgRGEzOz9U&hl=en&sa=X&ei=tlkhUfom5p7LAbv4gbAH&ved=0CD8Q6AEwAg#v=onepage&q=how%20to%20determine%20direction%20reaction%20when%20comparing%20strengths&f=false

Thanks. Is there a way to tell how one acid is weaker than the other or do you have to memorize the charts?

To determine the direction of the reaction based on the relative strengths of acids and bases, we need to understand the concepts of acid-base equilibrium and the concept of comparing acid and base strengths using the equilibrium constant expressions (Ka and Kb).

In this case, we have an acid-base reaction between H2S, a weak acid, and C2H3O2-, a weak base. The products of the reaction are Hc2H3O2, a weak acid, and HS-, a weak base.

To determine the favored direction of the reaction, we can compare the strengths of the acids and bases involved using their respective Ka and Kb values. In general, a reaction will favor the formation of weaker acids and bases, and the reverse reaction will favor the formation of stronger acids and bases.

In this reaction, H2S and C2H3O2- are both weak acids and bases. Without more information about the specific values of Ka and Kb for these species, we cannot make a definite determination about their relative strengths.

However, the fact that Hc2H3O2 is formed as a product suggests that it is a weaker acid compared to H2S. This implies that the reaction may favor the forward direction, which is the formation of Hc2H3O2 and HS- from H2S and C2H3O2-.

So, based on the available information, it is likely that this reaction will favor the formation of Hc2H3O2 and HS-, and hence the reactants. However, without precise values for the relative strengths of the acids and bases involved, it is not possible to make a definitive determination about the direction of the reaction.

To determine the direction of a reaction based on the relative strengths of acids and bases, you need to consider the concept of acid-base equilibrium. In this reaction, H2S acts as a weak acid and C2H3O2- acts as a weak base.

The reaction can be written as follows:

H2S(aq) + C2H3O2-(aq) ⇌ Hc2H3O2(aq) + HS-(aq)

In this case, H2S donates a proton (H+) to C2H3O2-, forming Hc2H3O2 and HS-. We can view HS- as a relatively stronger base compared to C2H3O2-, and Hc2H3O2 as a relatively weaker acid compared to H2S.

When comparing the strengths of acids and bases, we can make the general observation that a stronger acid-base pair will favor the formation of the weaker acid and weaker base. In this reaction, since HS- is a stronger base than C2H3O2-, and Hc2H3O2 is a weaker acid than H2S, the reaction will tend to favor the reactants - H2S and C2H3O2-.

To conclude, the book is correct in stating that this reaction will favor the reactants H2S and C2H3O2- due to the relative strengths of the acid-base pairs involved.