[StaticRoar]

1st Problem: A solution is made up using equal volumes of 2.0 M acetic acid (Ka = 1.8x10-5) and 0.00050 M HCl. What is the pH of this solution?

Pretty sure I have the process correct, but I'm a little unsure on the initial concentrations. The initial concentrations are 1.0M for acetic acid and 0.00025 M for HCl, right?

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2nd Problem: Suppose in the above problem (at the top of OP), 4.0M sodium acetate was also added such that the initial concentrations of each of the chemicals were as follows: 1.0M acetic acid, 0.00025M HCl and 1.0 M sodium acetate. What is the pH of this new solution?

This is the one I'm really stuck on. I used the equation: C2H3O2+H2O<-->HC2H3O2+OH. I solved for the initial concentration of OH, using the concentration of H found in HCl-->H+Cl. Then I solved for kb, by using kb=kw/ka. Then I used the ICE table to get [OH][HC2H3O2]/[C2H3O2]=kb. But I get a faulty value for x. What am I doing wrong? If what I said is too hard to follow, giving the step-by-step in your own words would probably be just as helpful. Thanks.

[StaticRoar]

Just stumbled across another one I'm having trouble with, but this time I have no idea how to start or what to do. Any help is very much appreciated.


Silver acetate is insoluble in water. If 0.6M acetic acid (Ka=1.8x10-5) and an equal volume of 0.8M silver nitrate are mixed together, what is the pH of the solution?

[Borek]

The initial concentrations are 1.0M for acetic acid and 0.00025 M for HCl, right?

Yes.

2nd Problem: Suppose in the above problem (at the top of OP), 4.0M sodium acetate was also added such that the initial concentrations of each of the chemicals were as follows: 1.0M acetic acid, 0.00025M HCl and 1.0 M sodium acetate. What is the pH of this new solution?

Is it possible to have both acetate and HCl at the same time in the solution?

All questions you have asked so far are in fact related to the pH of buffers. See if this page: http://www.chembuddy.com/?left=buffers&right=composition-calculation doesn't help. There are no questions that are identical to the ones you are working on, but all necessary principles are mentioned.

Silver acetate is insoluble in water. If 0.6M acetic acid (Ka=1.8x10-5) and an equal volume of 0.8M silver nitrate are mixed together, what is the pH of the solution?

I don't get the question. How can you have 0.8 M silver acetate, if silver acetate is insoluble? (actually saturated silver acetate is around 0.06 M, which is definitely important for the answer to the question about pH).

[StaticRoar]

The initial concentrations are 1.0M for acetic acid and 0.00025 M for HCl, right?

Yes.

2nd Problem: Suppose in the above problem (at the top of OP), 4.0M sodium acetate was also added such that the initial concentrations of each of the chemicals were as follows: 1.0M acetic acid, 0.00025M HCl and 1.0 M sodium acetate. What is the pH of this new solution?

Is it possible to have both acetate and HCl at the same time in the solution?

All questions you have asked so far are in fact related to the pH of buffers. See if this page: http://www.chembuddy.com/?left=buffers&right=composition-calculation doesn't help. There are no questions that are identical to the ones you are working on, but all necessary principles are mentioned.

Silver acetate is insoluble in water. If 0.6M acetic acid (Ka=1.8x10-5) and an equal volume of 0.8M silver nitrate are mixed together, what is the pH of the solution?

I don't get the question. How can you have 0.8 M silver acetate, if silver acetate is insoluble? (actually saturated silver acetate is around 0.06 M, which is definitely important for the answer to the question about pH).

Thanks for the help. We never went over the Henderson equation in class so I think I'm safe. As for the last equation, we have 0.8 M silver nitrate, not silver acetate.

[Borek]

We never went over the Henderson equation in class so I think I'm safe.

HH equation is just a rearranged dissociation constant formula. Whatever you can calculate with HH equation can be also calculated using dissociation constant definition, HH equation is just much more convenient.

As for the last equation, we have 0.8 M silver nitrate, not silver acetate.

Sorry, my mistake, I misread the problem.

Then it is just a matter of finding what is left in the solution after silver acetate precipitates. You are most likely expected to assume precipitation went to completion. Whatever is left in the solution, will define pH.