All Questions
Tagged with equilibrium ph
139
questions
-1
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0
answers
32
views
Algebraic method for modelling sodium acetate in solution
For a solution of sodium acetate ($NaA$), I want to find the concentrations of $H^+$, $OH^-$, $HA$ and $A^-$ via the algebraic method, being the total concentration of $NaA$ $C_A=0.25~\text{M}$, the ...
- 337
-2
votes
1
answer
49
views
Hydrolysis of $A_3B$ type weak acid-weak base salt
I know the formulae for weak acid-weak base salt of AB type. A peculiar question made me ask this. Do the formula for derived for AB type also hold for A3B type sal.
For example:
This is the question, ...
- 93
-5
votes
1
answer
113
views
Find the pH of a solution obtained by mixing 100 ml 0.1m Na3PO4 and 100 ml 0.1 M NaH2PO4. Given that H3PO4: [Κα₁ = 10^-4, Κα₂ = 10^-7, Каз = 10^-11] [closed]
So, my query is that since NaH2PO4 is a weak acid, and Na3PO4 is a basic salt, wouldn't they react? Another theory was that since NaH2PO4 is a weak acid and Na3PO4 is a salt of strong acid and NaH2PO4,...
1
vote
0
answers
41
views
How to calculate the pH of a mixture of an acid with a buffered solution?
Being a physicist by training, having worked in software development for the last 10 years. Having heard my last chemistry lecture 15 years a go I am a bit lost in regards to how one can calculate the ...
- 111
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
0
votes
1
answer
149
views
pH calculation of HCOOH +plus HCl solution
Question - What volume of $0.1 \ce{M}$ $\ce{HCl}$ solution should be
added to a $\ce{500 mL}$ of $\ce{0.5 M }$ $\ce{HCOOH }$ solution in
order to prepare an acid solution of $\text{pH}$ =$1.5.$ $K_a$...
- 185
1
vote
0
answers
410
views
Determine the pKa of a diprotic acid by titration (if pKa1 is similar to pKa2)
Determining the acidity constants of a diprotic acid (in my case, tartaric acid) by titration with NaOH and pH-meter is not possible if pKa2 - pKa1 < 2.
This is because there are no "pH jumps&...
- 109
1
vote
0
answers
254
views
How to calculate pH of a 0.1 M solution of ammonium bicarbonate considering simultaneous equilibrium along with hydrolysis?
We need to calculate the $\ce{[H+]}$ of 0.1M $\ce{(NH4+)(HCO3^-)}$ given the $\ce{k_b(NH4OH), k_{a_1}(H2CO3), k_{a_2}(HCO3^-)}$
The hint tells me to directly use the result $\ce{[H+]=\sqrt{k_{a_1}(\...
- 35
-1
votes
1
answer
148
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pH and degree of dissociation of drugs
I have a doubt, i hope not so stupid.
Suppose we consider a buffer solution of acetic acid/acetate at pH = pKa = 4.76 and we add aspirin (pKa = 3.5): given that the pH of the solution is higher than ...
- 127
-3
votes
2
answers
1k
views
How to determine the charge of amino acid at certain pH? [duplicate]
Problem
What would charge would you expect on alanine when placed in a solution with a pH of 1.00?
Answer
Question
Let's say I am given a certain pH of 2.00 rather than 1.00 for the "acidic ...
- 11
0
votes
1
answer
1k
views
I tested the effect of temperature on the pH of carbonated water but the results seem to go opposite to what was expected. Could anyone explain?
We carried out an experiment to investigate the effect of temperature on the acid carbonate equilibrium in carbonated water. We tested 5 different temperatures (room temp, 2 above and 2 below) by ...
3
votes
2
answers
144
views
What happens to the hydroxide ion concentration when you add caustic soda to ammonia?
Question.
Find the $[\ce{OH-}]$ and the pH of a $\pu{0.20 M}$ $\ce{NH3}$. If given $\pu{1 L}$ of the previous solution, when adding $\pu{100 mL}$ of $\pu{0.2 M}$ $\ce{NaOH}$, what would be the new ...
- 53
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
63
views
Zwitterionic Form in Amino Acid
In my laboratory workbook, it has been mentioned that the zwitterionic form of the amino acid is the dominant form of the amino acid at pI and no movement of the molecules takes place under an ...
- 795
1
vote
0
answers
105
views
How does pH affect an extraction problem
I am not sure how to understand when pH will affect a given problem regarding extraction. For example, in a problem given that K$_D$ of the reaction is $1.86$ I am asked to calculate:
(a) How much ...
- 1,095
3
votes
1
answer
595
views
Calculate pH of imidazole in solution
I am having trouble understanding how to know how a molecule will reaction in solution. For example, if I have $\pu{1 M}$ of imidazole in solution, how can I calculate the pH of the solution by only ...
- 1,095
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
0
votes
0
answers
137
views
How to estimate the pH of multi-component buffer (phosphate buffer in equilibrium with CO2 rich atmosphere)?
I wonder how the pH of buffer solution can be estimated if buffer consists of several systems in equilibrium to the gas phase. For example, (based on growth medium for one of the bacteria) buffer ...
- 151
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
5
votes
1
answer
2k
views
Does pressure affect pH? [closed]
Since pH is the function of $\ce{H+}$ ion concentration, the change in volume will change the equilibrium according to Le Chatelier's principle and affect the pH. Is it correct, or are there any ...
- 73
0
votes
0
answers
151
views
pH for an HA/NaA solution using a contour map
The following question has troubled me for a while now.
A virtual weak acid $\ce{HA}$ dissociates as follows:
$\ce{HA <=> H^+ + A^-}$
with the acid dissociation constant $K_\mathrm{a} = 10^{-3....
- 605
2
votes
2
answers
77
views
Auto-ionisation and Dilution
When you dilute an acidic solution, pH increases towards 7 and pOH decreases. However, the decrease of pOH indicates that the concentration of hydroxide ions increases. This seems to contradict my ...
- 37
1
vote
0
answers
485
views
Equivalence point pH derivation of a tribasic acid
Considering $\pu{100 mL} \ \pu{0.1 M} \ \ce{H3A}$ and $\pu{0.1 M} \ \ce{NaOH}$ titration curve:
I understood the half equivalence points, but couldn't understand the reason why $\mathrm{pH} = \frac{1}...
- 412
0
votes
2
answers
787
views
Calculating the pH of a 'buffer' solution?
Question: Determine the $\mathrm{pH}$ of the solution resulting when $\pu{100 cm^3}$ of $\pu{0.50 mol dm-3}$ $\ce{CH2ClCOOH}$ is mixed with $\pu{200 cm^3}$ of $\pu{0.10 mol dm-3}$ $\ce{NaOH}$.
The ...
- 153
-1
votes
1
answer
161
views
Finding a Mistake Calculating the pH of Ammonium Acetate
I'm trying to calculate the $\mathrm{pH}$ of a $\pu{0.10 M}$ solution of ammonium acetate, and I am struggling to find what mistake I am making within the following calculations:
We know that $\dfrac{[...
- 102
0
votes
2
answers
344
views
Neutralisation of weak acid by base
I'm still working on my concepts related to chemical equilibrium. I came across this question:
10mL of a weak acid HA is 20%
dissociated in water. This solution is completely neutralised by 10 mL
of $...
- 149
4
votes
0
answers
74
views
Decomposition of Hydrogen Peroxide Catalysed by Potassium Iodide in Basic Solution
As part of my high school project, I had to measure the initial rate of decomposition of hydrogen peroxide catalysed by potassium iodide at different pHs. At higher pHs (alkaline conditions), I found ...
- 41
-2
votes
1
answer
351
views
Why does the pH of the endpoint decrease when temperature of the titration is increased? [duplicate]
I was doing an experiment in chemistry class involving titrations. I would heat up different samples of vinegar and titrate them using NaOH. The trend that I found was how has temperature increase, ...
- 9
3
votes
3
answers
994
views
salt hydrolysis and pH calculations
I am a high school student and I am very confused in salt hydrolysis
My confusion is that: when we talk of hydrolysis of salt of weak base and weak acid, we internally assume the degree of hydrolysis ...
- 252
1
vote
1
answer
393
views
Why does the pH of a weak acid not increase by 1 when diluted by a factor of 10? [closed]
Strong acid pH increases by one unit when diluted by a factor of 10, but why do weak acids not?
- 23
2
votes
0
answers
48
views
A trick to find resultant pH [duplicate]
Consider the following problem:
Find the $\mathrm{pH}$ of the solution formed by the mixing of two solutions of $\mathrm{pH}$(s) $2$ and $3$ of equal volumes.
The normal way:
Since the resulting ...
- 397
-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
4
votes
3
answers
253
views
Is pK_{In} = pH at equivalence point still true for weak basic organic indicators?
I am reading Ostwald Theory of Titration which says that indicators are organic weak acids or bases.
To prove the relation that $\mathrm{p}K_\mathrm{In} = \mathrm{pH}$, the textbook uses the following ...
- 261
1
vote
0
answers
259
views
Calculating the pH of a sodium phosphate solution [closed]
I have the following question in a chemistry homework:
Calculate the $\mathrm{pH}$ of a solution made by dissolving $\pu{113 g}$ of sodium phosphate in enough water to make a solution with a final ...
- 21
-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
0
votes
3
answers
158
views
How to simplify these system of equilibrium equations
What is the pH when $0.025$ mol $\ce{NiCl2}$ is added to $\pu{1.00 L}$ of a $\pu{0.100 M}$ solution of $\ce{HCN}$, if the formation constant for $\ce{Ni(CN)4^2-}$ is $K_f=\pu{1.0e22}$, and the $K_a$ ...
- 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
1
vote
0
answers
79
views
How do I find pH of a mixture of weak acids? [duplicate]
Suppose that we are given two weak bases $\ce{HA_1}$ and $\ce{HA_2}$. We are also given the $K_\ce{HA_1}$ and $K_\ce{HA_2}$. How can we calculate the $\mathrm{pH}$ of the mixture?
- 144
-2
votes
2
answers
2k
views
pH of strong acid weak acid mixture [closed]
Question: $\ce{H2S}$ ($\pu{0.1M}$; $K_\mathrm{a} = 1.2×10^{-20} $) and $\ce{HCl}$ ($\pu{0.3M}$) with same volume are mixed together. What is the resultant $\mathrm{pH}$?
My approach:
Let the volume ...
- 117
2
votes
1
answer
3k
views
Calculating molecular weight of an acid based on given values of mass, volume, pH and pKa
This is what I thought was an easy problem but according to a given answer I am doing it wrong:
$\pu{11 mg}$ of a monoprotic acid was dissolved in $\pu{0.5 l}$ of water. The resulting $\mathrm{pH}$ ...
- 51
1
vote
1
answer
179
views
Calculating pH of weak base and strong acid: Why is K(a) not required?
Question: 35mL of 1.5M $\ce{HCN}$, a weak acid(K(a)= $6.2*10^{-10}$) is mixed with 25mL of 2.5M $\ce{KOH}$. Calculate the pH of final solution.
The solution given in my textbook is as follows:-
$\ce{...
user62318
1
vote
1
answer
2k
views
When there is an increase in temperature, how is the pH of the ocean affected? (Question is related to ocean acidification)
This is my current understanding:
Ocean acidification is the result of atmospheric $\ce{CO2}$ dissolving in the ocean's water. When this occurs the $\mathrm{pH}$ of the ocean decreases (from the ...
- 11
0
votes
1
answer
3k
views
pKa value of an indicator
Can we deduce the actual value of $\mathrm{p}K_\mathrm{a}$ of an indicator if the $\mathrm{pH}$ range has been given?
I know that $\mathrm{pH}$ range is physically the range of values over which an ...
- 54
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
0
answers
570
views
Impact of pH? Change in Binding Affinity of protein-ligand complex based on pH and Kd?
When the $\mathrm{pH}$ was $5.0$, the temperature was $\pu{25 °C}$,the $K_\mathrm{D}$ was $\pu{5 μM}$, and [L] was equal to $K_D$, the protein(s) were half bound.
Question considers half bound ...
