All Questions
Tagged with equilibrium ph
139
questions
-1
votes
1
answer
432
views
How do I calculate the amount of polyprotic acid and base needed to achieve a certain buffer pH?
e.g. Citric Acid and Trisodium Citrate
$\ce{H3C6H5O7 <=>[ka_1] H2C6H5O7- + H+ <=>[ka_2] HC6H5O7^2- + H+ <=>[ka_3] C6H5O7^3- + H+}$
Using the definition of Ka and substituting for ...
1
vote
1
answer
488
views
Why doesn't pH = pKa1 in the buffer zone for this titration?
Below is an image from my textbook representing the titration curve for the titration of $5.00\ \mathrm{mL}$ of $0.010\ \mathrm M$ $\ce{H2S2O3}$ with $0.010\ \mathrm M$ $\ce{KOH}$, which has $\mathrm ...
- 2,109
3
votes
1
answer
20k
views
How to calculate pH of the Na2CO3 solution given ambiguous Ka values
This is the exact question I faced on an exam:
Calculate the $\mathrm{pH}$ of $\pu{0.05 M}~\ce{Na2CO3}. \\(\ce{H2CO3}: K_\mathrm{a_1}= 4\times 10^{-7},~ K_\mathrm{a_2}= 4.7\times 10^{-11})$
Solution
...
- 41
5
votes
2
answers
2k
views
Calculate pH of a weak acid and weak base neutralization reaction
I'm an industrial pharmacist needing some help with some chemistry basics.
I'm trying to calculate the theoretical pH of an effervescent preparation containing 2 mmol citric acid ($\ce{H3C6H5O7}$), 4 ...
- 69
1
vote
0
answers
222
views
Calculating the pH of a weak acid from the Kb of its conjugate base
I'd start off by saying it's been many years since I was in chemistry lessons and have forgotten much, but recently I have had to relearn a lot of basic chemistry. The following doesn't really impede ...
- 111
-3
votes
1
answer
2k
views
Calculating PH of solution after adding strong acid (equilibrium)
Consider the classic example when talking about acids and bases:
Say you have 1M of $\ce{HCL}$ and you throw it into water, calculate the resulting pH (= concentration of $\ce{H3O+}$).
The way this ...
- 129
-3
votes
1
answer
614
views
What mass of potassium lactate is needed to 300.0 mL of 0.238 M Lactic acid solution to make a solution with a pH of 4.00? pKa (lactic acid) =3.86
Upon attempt, I've yielded an answer of 11.91g. My calculations do not take 300 mL Lactic acid solution into account, and now I somewhat know the error is at least partially due to the fact that my ...
0
votes
2
answers
13k
views
How do I find the theoretical pH of a buffer solution after HCl and NaOH were added, separately?
This question is about the theoretical pH of a buffer solution.
Calculate the theoretical pH values expected for a $\pu{200mL}$ buffer solution containing a 1:1 ratio of acetic acid and sodium ...
- 9
0
votes
1
answer
665
views
What is the citric acid concentration, [HCit], in the lemon juice?
The pH of lemon juice is about 2.1. What is the citric acid concentration, [HCit], in the lemon juice?
I am given that $HCit \leftarrow \rightarrow H^+ + Cit^-$ and that $K_a = 8.4 \times 10^{-4}$.
...
- 209
1
vote
0
answers
321
views
Henderson-Hasselbalch approximation
The Henderson-Hasselbalch approximation gives us a method to approximate the pH of a buffer solution. The basic equation is as follows:
$$\mathrm{pH} \approx \mathrm{p}K_\mathrm{a} + \log\dfrac{\ce{[A^...
- 303
0
votes
1
answer
12k
views
Find the half equivalence point
How to find the half equivalence point knowing the pH, molarity, titrant added at equivalence point?
This a fairly straightforward and simple question, however I have found many different answers to ...
-1
votes
1
answer
108
views
Redox - concentration cell
I'm studying galvanic cells and I've found a demonstration that lead me to an impossible result, so there must be a mistake, but I can't find what it is.
My problem is about concentration cells made ...
- 197
1
vote
2
answers
212
views
Weight of sodium acetate required to get to certain pH
How many grams of $\ce{CH3COONa}$ we need to dissolve in $\pu{2.50 L}$ of water to get a solution with $\mathrm{pH} = 9.00$? Given $K_\mathrm{a}(\ce{CH3COOH}) = 1.75\cdot 10^{-5}$
Like solving a ...
- 305
2
votes
1
answer
2k
views
Mixing Ca(OH)2 with Ca(NO3)2
Mixing $\ce{Ca(OH)_2}$ with $\pu{0.1 M}$ concentration of $\ce{Ca(NO3)2}$.
What will actually happen in the process? What I will see with my eyes? I know that $\ce{Ca^2+}$ cation with concentration ...
- 305
-1
votes
1
answer
57
views
Can i calculate the solution of the problem in more simple way?
and i got a serious question. During my exercises at home, i found that im struggling a lot while solving simple problem`s like this one:
I have an aquatic substance with 0.100 M of $\ce{Mg(NO3)2}$ ...
- 305