Grimm

I don't think I've tried that. So I wasn't using the correct set up then? The question tells me to use a specific method. I will try it though, thanks. The ka of Acetic Acid is 1.75 E-5 -log(ka) = pka = 4.757 [A-] = [C2H3O2-] = .151 M [HA] = HC2H3O2 = .082 M pH = 4.757 + log(.151/.082) pH = 1.261 Do I have this right?

Hi everyone. I'm sure you're all glad I'm back with another chemistry problem giving me problems. You can see below is the attached question. Here is the work I have for it. kb = kw/ka = 1 E-14 / 1.8 E-5 = 5.55 E-10 NaC2H3O2 .151 M HC2H3O2 .082 M C2H3O2- + H2O <--> HC2H3O2 + OH- I .151 .082 0 C -x +x +x E .151-x .082+x x kb = [HC2H3O2][OH-] / [C2H3O2-] 5.55 E-10 = [.082 + x][x] / [.151 - x] Since the kb is so low we can make assumptions and use the 5% rule. 5.55 E-10 = [.082][x] / [.151] x = 1.023 E-9 = [OH-] -log[OH-] = 8.990 = pOH 14 - pOH = 5.010 = pH Someone please help me. I already have it marked wrong so right now my main concern is just making sure that I know it for the exam. Please let me know where I went wrong here.

Thank you again studiot! I definitely have to watch my starting concentrations more closely in the future. Laziness and hubris, bad combo.

I would like to announce that I have solved the problem. The only thing I did wrong was the beginning concentrations! I feel so stupid. I think I was remembering earlier problems that always tried throwing in different amounts of molarities and container sizes to make sure you were paying attention. M1V1 = M2V2 (.20 mol/L)(.5 L) = M2(1.0 L) .1 mol = M2(1.0 L) .1 mol/L = M2 If I use this in my ICE table, I get the right answer. pH=5.13 ka = [H3O+][NH3] / [NH4+] 5.6 x 10^-10 = [x^2] / [.10 - x] With such a small k value I can use the 5% rule. 5.6 x 10^-10 = [x^2] / [.10] 5.6 x 10^-11 = [x^2] 7.48 x 10^-6 = x = [H3O+] -log(7.48 x 10^-6) = 5.13 = pH Thanks to everyone that helped!

At the start of the reaction the volume of the mixture would have to be 1 L. As for the number of moles of each, n=CV HBr n= (.20 M)(1 L) HBr n= .20 moles NH3 n= (.20 M)(1 L) NH3 n= .20 moles So the concentrations of each would have to be [HBr] = .20 mol/L and [NH3] = .20 mol/L

Ok I don't know shit then. Will you help me now? It was my understanding that it doesn't double the actual amount in the container but the concentration would be greater since it's the same amount of material in a smaller container. Please enlighten me if this is not the correct way to approach this.

If 500.0 mL of a 0.20 M solution of ammonia is mixed with 500.0 mL of a 0.20 M solution of HBr, what is the pH of the resulting solution of NH4Br ? The above is the question I'm trying to answer. I converted the .20 M because M stands for mol/L and the volume for the question is given in mL. .20 mol /.5 L = .4 M

Damn, I thought someone here could help me for sure. Thanks for your time.

Yes, I know that k=products/reactants. This won't help find the concentration of H+ or OH- unless I know the k values first. If I try using: NH4+ + H2O <---> H3O+ + NH3 I get a pH of 4.82 The book says the answer is 5.13 Wish I knew exactly what I was doing wrong here. If 500.0 mL of a 0.20 M solution of ammonia is mixed with 500.0 mL of a 0.20 M solution of HBr, what is the pH of the resulting solution of NH4Br ?

500 mL of 0.20 M solution of Ammonia is mixed with 500 mL of 0.20 M solution of HBr. What is the pH of the resulting solution of NH4Br? Ok, so I know the general math required. I'm just not sure how to proceed here. I'm using mostly the book provided and I'm not seeing an example of how to proceed. .20 M / 500 mL = .40 M NH3 + H2O <---> OH- + NH4+ HBr + H2O ---> H3O+ + Br- I know NH3 is a weak base, and HBr is a strong acid. How do I find the pH of a mixture of two different solutions. Seriously my book says nothing about this. Should I just use the formula for NH4Br? What would the k value of NH4Br be? Any help would be greatly appreciated. Thank you.

My program already has potential jobs lined up for me. There is a biotech business park (called the Incubator) partnered with my school and they recruit mainly from it. One place I'm interested in produces gene therapies for those missing a gene necessary for proper vision. I already know I like the field and the work I've done so far. The first job I get from my program will serve as a testing ground. I'm hoping that it will lead to me finding new areas of study I might also like. I'll keep going higher if I see that I like those positions. All predicated on actually getting into these places though. Which is why I started this thread, to talk to people already there. Anyone mind sharing their stories with me? Either way, my first job in my career preference will be loads better than where I currently work: Wal-Mart.

Hi everyone. I'm currently pursuing a career in these areas since I find it fascinating and there seems to be a good degree of overlap between them. I'm almost positive I will like the work because I've been doing lab work as part of my education. What I'm curious to know is if any of you have any insights or suggestions you would like to give your younger self? Maybe a source of cheap trade magazines or online resources. Do any of you currently work in these fields? How do you feel about what you do? Thanks