All Questions
27
questions
2
votes
4
answers
172
views
How can the Kw of water be constant?
I know in neutral solution, $\ce{[H+]}= \ce{[OH-]}= \pu{1.0 x 10^-7}$.
However, let’s say I add an acid like HCl. This will increase $\ce{[H+]}$, therefore it’s no longer $\pu{1.0 x 10^-7}$, but is ...
- 41
1
vote
2
answers
262
views
What is the significance of charge balancing when analysing system speciation (carbonate system given as an example)?
Following on from my previous question and accepted answer, How do I quantify the carbonate system and its pH speciation?, I also calculated a charge balance ($CB$) on the system where $z$ is the ...
- 500
4
votes
1
answer
1k
views
How do I quantify the carbonate system and its pH speciation?
I did Environmental Water Chemistry as part of my undergraduate course where we quantified pH-speciation for the full carbonate system and I got it right according to my tutor. My speciation profile ...
- 500
0
votes
0
answers
72
views
Finding dissolved amount of base from pH and solubility product
Calculate the amount of $\ce{Mg(OH)2}$ which is solubilized in $\pu{1.25 L}$ of a buffered solution at $\mathrm{pH} = 9.5$. $(K_\mathrm{sp}(\ce{Mg(OH)2}) = \pu{5.61E-12})$.
From $\mathrm{pH}$ I ...
- 109
9
votes
2
answers
959
views
Numerically solving chemical equilibrium equations
Here are chemical equilibrium equations:
$\begin{cases}
\mathbf{N}^\text{T}\mathbf{X}+\mathbf{C}=\mathbf{Y}\\
\mathbf{N}\ln\mathbf{Y}=\ln\mathbf{K}
\end{cases}$
Here $\mathbf{C}=\begin{pmatrix}c_1\\...
- 219
1
vote
1
answer
366
views
Calculating pH of aqueous ammonium hydrogen sulfide solution
I was doing the following question yesterday:
Calculate the pH of a $\pu{0.1 M}$ solution of $\ce{NH4HS}$, given $\mathrm{p}K_\mathrm{b}$ of $\ce{NH3}$ is $4.74$, and $\mathrm{p}K_\mathrm{a1}$ and $\...
- 1,411
-3
votes
1
answer
5k
views
pKa = pH for strong acid — strong base?
I have learnt that for a weak acid — strong base titration, $\mathrm{p}K_\mathrm{a} = \mathrm{pH}$ at the half equivalence point.
However, the same conclusion is not drawn when discussing strong acid —...
- 153
5
votes
1
answer
403
views
Common Ion Effect - Ionic Equilibrium
Question
In which of the aqueous solutions of the following, dissociation of $\ce{NH4OH}$ will be minimum?
A) $\ce{NaOH}$
B) $\ce{H2O}$
C) $\ce{NH4Cl}$
D) $\ce{NaCl}$
My Thoughts
My book says that ...
- 309
-1
votes
1
answer
2k
views
How to calculate the amount of water required to increase the pH of a solution from 2.1 to 4? [closed]
After working out the problem with certain approximation of considering the initial pH=2, my answer came out to be around 1 litre of water. But the correct answer is 79 litres of water. Can anyone ...
- 11
0
votes
2
answers
431
views
pH of amphoteric species
For a solution of $\ce{HA-}$, I have seen the following approximations for the $\mathrm{pH}:$
$$\mathrm{pH} = \frac{1}{2}(\mathrm{p}K_\mathrm{a1} + \mathrm{p}K_\mathrm{a2})\tag{1}$$
$$\mathrm{pH} = \...
- 2,109
3
votes
2
answers
1k
views
Use of Concentration for pH
When we find the pH of a solution, do we use normality or molarity? My teacher said that if the compound is present by itself, we can use normality but in all other cases we should use molarity. Can ...
- 31
3
votes
2
answers
821
views
Calculating pH of rain water
The concentration of $\ce{SO2}$ in the atmosphere over a city on a certain day is $\pu{10 ppm}$. Given that solubility of $\ce{SO2}$ in water is $\pu{1.3653 mol L-1}$ and $\mathrm{p}K_\mathrm{a}$ of $\...
- 224
4
votes
2
answers
2k
views
Can I use the Henderson–Hasselbalch for calculating the pH of non-buffer systems?
Can I use the Henderson–Hasselbalch equation on reactions that are not buffers? When I read up on the derivation of the equation, I noticed that there is absolutely no assumption on the relative ...
1
vote
1
answer
14k
views
pH of CH3COOH + HCl solution (shouldn't be a buffer)
$\pu{0.05 L}$ of a solution containing $\pu{0.3 M}$ acetic acid $(\ce{CH3COOH}$, $K_\mathrm{a} = \pu{1.8e-5})$ are added to $\pu{75 mL}$ of a solution containing $\pu{0.02 M}$ hydrochloric acid ($\ce{...
- 19
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