chemistry
posted by Kelsy .
Hy Dr Bob222 this will be the last time I will bother you about this type of question. Can you please tell what I am doing wrong?
This is the best answer I could come up with:
Question: Strychnine, C21H22N2O2(aq) is a weak base but a powerful poison. Calculate the pH of a 0.001 mol/L solution of strychnine. The Kb of strychnine is 1.0 x 10^6.
Calling strychnine SN,
SN + HOH > SNH+ + OH
Kb = (SNH+)(OH)/(SN)
(SNH+) = x
(OH) = x
(SN) = 0.001  x
Plug Kb and solve for x = (OH)
1.0 x 10^6 = (x)(x)/0.001  x
x^2 = 1.0 x 10^9
x = 0.000031622
=log (0.000031622)
=4.5
pH = 4.5
OR
x^2 + 0.001x + 0.000001
Using quadratic formula gives
0.001+0.0015 or 0.0010.0015
= 0.0005 =negative answer
pH=log^0.005
=2.3
pH = 2.30

Thanks for showing your work. It helps us identify the problem(s).
Calling strychnine SN,
SN + HOH > SNH+ + OH
Kb = (SNH+)(OH)/(SN)
(SNH+) = x
(OH) = x
(SN) = 0.001  x
Note this next step. Note that x = (OH^) and not (H^+).
Plug Kb and solve for x = (OH)
1.0 x 10^6 = (x)(x)/0.001  x
x^2 = 1.0 x 10^9
x = 0.000031622
=log (0.000031622)
=4.5
pH = 4.5
Two things here.
#1. If you let 0.001x = 0.001, then x = 3.162 x 10^5 and your answer is correct. That is the simplifying assumption and causes a small error. I don't know what your prof allows but this is a little over 3%; i.e., (3.162 x 10^5/0.0010)*100 = 3.16%.
#2. If s/he allows this, then this is the (OH^) (note it isn't H^+ and this is your largest error) and (OH^) = 3.16 x 10^5, pOH = 4.5 and pH = 144.5 = 9.5 so we are at pH = 9.5 if your prof allows that small error.
OR
Next, on the quadratic formula, that isn't done correctly. I have shown that below in bold.
x^2 + 0.001x + 0.000001
Using quadratic formula gives
0.001+0.0015 or 0.0010.0015
= 0.0005 =negative answer
pH=log^0.005
=2.3
pH = 2.30
Starting with the original formula, we have (and I will use the E notation so as not to confuse x the unknown with x the times sign),
[(x)(x)/(0.001x)] = 1E6
x^2 = (0.001x)*1E6
x^2 = 1E9  1E6x
x^2 + 1E6x  1E9 = 0
Solving the quadratic formula we get, and I will leave that for you to do but I get x = 3.11 x 10^5 M = (OH^)
pOH = 4.507 which I would round to 4.51 and pH = 9.49.
You can see that the difference between 4.50 and 9.50 versus 4.51 and 9.51 is quite small. You know what the rules are in your class so it will be up to you to use the one that you should use but this gets the problem worked for you and I hope you can see why you had answers that didn't agree when worked by different methods. Please let me know if there is anything else. We are here to help. Again, thanks for showing your work. It makes the difference between guessing what you did wrong and knowing what you did wrong. 
No Sir, thank you :)
Respond to this Question
Similar Questions

math
how can you get the answer 16 using these numbers 4,3,2,1=16 you can not use any number more than one time. Help! 31=2 2x 2 =4 4x 4 =16 Bold face type show numbers in the problem. please help You need to post a question before we … 
General
Please understand that I am not upset with anyone or whatever I just want to know something. I have some work to be checked and the regular tutors here say that "we will be happy to critque your thinking" right? 
stat
ok there was a question that my teacher told me i got wrong the question asked me to compute the mean which I did... then the question went on to tell me compute the mean with another observation equal to zero then the part that he … 
chemistry
A 1.325 g sample of an unknown vapor occupies 386 mL at 114 celsius and 946 mmHg. The simplest formula of the compound is NO2. What is the molecular formula of the compound? 
English
Task2.Identify and choose the one word or phrase that should be corrected. 1.If(A) boss comes from(B) Moscow(C) everybody will get their(D) share(E). 2.Tom has never(A) spent his holiday(B) on the beach because(C) he(D) doesn't know … 
Chemistry
The boiling point of an aqueous solution is 102.16 C. What is the freezing point? 
Math
Need help with one more question. Which best describes a statistical question? 
Math Algebra
Question:: You are about to take a test that contains questions of type A worth 4 point and of type B worth 7 points. You must andwer at least 5 of type A and 3 of type B, but time restricts answering more than 10 of either type. Intotal, … 
Maths
There was a question: A gallon jug of milk is 3/4 full. After breakfast, you drink 1/12 of the milk. What fraction is the gallon is left? 
Art
As you try to answer the following question think about this question What does the expression of an angry superhero mean?