All Questions
Tagged with equilibrium acid-base
357
questions
-1
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0
answers
32
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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
-1
votes
2
answers
99
views
How can adding a strong base to a weak base be the same as a strong base in solution problem?
In professor's lecture on acid-base titration, professor says (at this point of the video, link should start about the time she says it)
"adding a strong base to a weak base should be treated as ...
- 257
2
votes
0
answers
58
views
Phase diagram of ammonium hydrosulfide, a volatile salt
Salts (ionic compounds) usually have low volatility due to the strong ionic bond.
However, there are exceptions. Smelling salts decompose and release ammonia gas.
What is "volatile"?
If a ...
- 972
-2
votes
1
answer
49
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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,...
-2
votes
1
answer
125
views
Can phosphorous penta hydroxide [P(OH)5] exist? [closed]
I was looking at the oxyacids of Phosphorous and it is given that (in Wikipedia article of "Phosphorous acid"), some of these acids (Eg: $H_3PO_2$ and $H_3PO_3$) exist in a dynamic ...
- 55
-1
votes
1
answer
130
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Why is the ionic product of water also the equilibrium constant of dissociation of water?
This answer presents a derivation of the value of ionic product of water at $25^{\circ}\text{C}$.
The relation $K_\text{eq} = \operatorname{e}^{-\frac{\Delta_\text{r}G^{\circ}}{RT}}$ is used for the ...
- 288
-2
votes
3
answers
343
views
Why are buffer solutions not neutral
I am very confused about buffer solutions and I have lots of ideas about them which don’t integrate together so I really can’t tell which are correct and which are wrong. That being the case it’s ...
2
votes
0
answers
40
views
Is the amine nitrogen of methylglycinediacetic acid (MGDA) protonated?
MGDA is a tertiary amine with 3 acetic acid groups. I would like to know whether the amine Nitrogen of MGDA is protonated or not for a given pH value. I could not find any literature data which ...
- 29
2
votes
3
answers
257
views
How to calculate the pH of a solution with addition of a complex
The scenario is this. I have $50$ mL of $0.1$ M $\ce{NH4^+}$ at a certain temperature which gives it a $K_a=5.2\times 10^{-8}$. To this solution, I add $0.02$ moles of $\ce{Cd(NO_3)_2}$. It is known ...
- 253
1
vote
0
answers
42
views
Why is it that in a buffer solution the equilibrium concentrations may be assumed to be the initial concentrations? [duplicate]
Considering the Henderson–Hasselbalch equation,
$$\text{pH} = \text{p}K_a + \lg \frac{[\ce{AcO⁻}]} {[\ce{AcOH}]}$$
$$\text{p}K_a = \lg \frac{[\ce{AcO⁻}][\ce{H⁺}]} {[\ce{AcOH}]}$$
Why are the values ...
- 11
2
votes
1
answer
103
views
Equilibrium Solubility of CO2 in Aqueous Solution and its Dependence on H3O+ Concentration
The equilibrium solubility of $\ce{CO2}$ in an aqueous solution is given by three chemical reactions:
$$
\begin{align}
\ce{CO2(g) &<=> CO2(aq)}\label{rxn:R1}\tag{R1}\\
\ce{CO2(aq) + H2O &...
1
vote
1
answer
107
views
What are the dissociation constants of hydronium and hydroxide ions? [duplicate]
Context
The answer to How to calculate Ka for hydronium and Kb for hydroxide?, water was regarded as solvent once and base (or equivalently acid) once while citing Reference 1 (1986) and made no ...
- 2,304
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&...
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-4
votes
2
answers
88
views
Successive deprotonation - how far can it go?
It has been written that among the equilibria of the dissolution of $\ce{SO_2}$ in water, the dissociation of sulphur dioxide into $\ce{HSO_3^-(aq) + H_3O^+(aq)}$ is a complete dissociation. See the ...
- 301
-3
votes
1
answer
148
views
Side reaction of I− and acidity of HI
In acidic conditions, I− tends to get oxidised by atmospheric oxygen to give iodine. This is evident in iodine based titration, where upon leaving the setup, blue colour of starch reappears as iodine ...
- 155
-4
votes
1
answer
66
views
How to make NH3 + H20 favor its products (NH4+ and OH-) [closed]
I am putting together a (fake) proposal for a process that would convert ammonia in cow manure into elemental nitrogen. The first step includes the conversion of that ammonia into ammonium so that it ...
- 1
-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
1
vote
2
answers
629
views
Calculate the pH at the equilibrium point in an acetic acid sodium hydroxide titration
You perform a titration of $\ce{CH3COOH}$ with $\ce{NaOH}$. Let the original concentration of acetic acid be $\pu{0.2 M}$. The volumes of $\ce{CH3COOH}$ and $\ce{NaOH}$ are the same. Then the ...
- 45
-4
votes
1
answer
524
views
Calculating equilibrium constant for a general acid base reaction
I am trying to find the equilibrium value for different acid-base reactions. I have understood that when an acid and base are in an aqueous solution, many different reactions will occur. By combining ...
- 45
-4
votes
1
answer
137
views
how to neutralize stannous chloride (50ml) to make it safe for disposal
I made a small quantity of stannous chloride by dissolving tin in muriatic acid - I would like to neutralize it for safe disposal - will mixing it with soda bicarbonate dissolved in water accomplish ...
- 1
0
votes
0
answers
84
views
Does temperature affect ionic strength?
Hello I apologize if this is a dumb question but if I have a phosphate buffer made up of Na2HPO4 and NaH2PO4 and I gradually increase the temperature (lets say 10,20,30,40,50) what would happen to the ...
- 11
3
votes
2
answers
856
views
Why can't the product of an acid reacting with water react with water itself and produce OH-?
Why can't the product of an acid reacting with water react with water and produce $\ce{OH-}$?
Take the reaction below as an example:
$$\ce{H2CO3(aq) + H2O(l) <=> HCO3-(aq) + H3O+(aq)}$$
$$\ce{...
- 157
10
votes
1
answer
422
views
Experimental evidence for zwitterions
If I have a diprotic acid that is +1 positively charged in its fully protonated state, I can figure out the apparent equilibrium constants by titration with base. The net charge will be neutral after ...
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0
votes
1
answer
1k
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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 ...
0
votes
0
answers
75
views
How to calculate the buffer capacity for polyprotic acids? specifically H2PO4 --- HPO42- + H30+
as the title says. Is b= amount of OH-/ H3O divided by volume of buffer x change in pH wrong to use with polyprotic acids? Can I calculate the buffering capacity of a sodium phosphate buffer made up ...
- 11
-3
votes
2
answers
246
views
Calculate the concentration of HF in aqueous solution of NH4F and NH4HF2 mixture
There is a similar question on this site, but here i have a mixture.
I have a mixture of NH4F (35% weight) and NH4HF2 (8% weight) in water. How do I calculate the weight % expressed in HF? or the ...
- 1
-1
votes
1
answer
114
views
Why phenolphthalein is not completely neutralized in basic solutions? [closed]
Phenolphthalein $(\ce{HIn})$ is slightly acidic. Why doesn't it completely break down into $\ce{H+}$ and $\ce{In-}$ and also reacting with all of the $\ce{OH-}$ ion present, unlike $\ce{NaOH}$ and $\...
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
2
votes
2
answers
547
views
Can a weak acid ever fully dissociate?
From what I understand, the pH of the solution the weak acid is added to determines the extent that the weak acid will dissociate. But would there be a pH which would allow the weak acid to fully ...
- 21
0
votes
1
answer
182
views
Does the acidity constant depend on the solvent?
Today I came across $pK_a$ values that depend on the solvent. For the hypothetical reaction $HA \rightarrow H^+ + A^-$, I had in mind that the acidity constant is defined simply as $K_a = \frac{\{H^+\}...
- 17
1
vote
2
answers
262
views
What is the significance of charge balancing when analysing system speciation (carbonate system given as an example)?
Following on from my previous question and accepted answer, How do I quantify the carbonate system and its pH speciation?, I also calculated a charge balance ($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
1
vote
0
answers
27
views
Notation for acid-base reactions of differing strengths - equilibrium?
I'm having trouble finding anything meaningful in textbooks or searches. My question is what is the correct notation for writing acid-base reactions when their strengths are varying? I know that ...
- 23
-2
votes
2
answers
355
views
Acidity and Basicity of titrate and titrant in Acid-Base titration
I want to know that do we always use monoprotic acid and bases in the Acid-Base Titration. And, if the answer is No. Then, I am confused in the definition of Equivalence Point, because I had seen on ...
-1
votes
1
answer
107
views
Between compounds having same functional groups, why does the one with greater -I effect have higher acidic strength
Consider the two compounds $\ce{FCH2COOH}$ and $\ce{ClCH2COOH}$.
Since fluorine is more electronegative than $\ce{Cl}$ it will show a greater –I effect.
It will pull the the electrons closer towards ...
- 21
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
-1
votes
1
answer
737
views
Why is HONH2 basic?
I've been told that $\ce{HONH2}$ is a weak base because of its $K_b$ value of $\pu{1.1E-8}$. However, the $K_a$ value is larger ($K_a=K_w/K_b=9.9\times10^{-7}$), which I think would make it more ...
- 105
0
votes
0
answers
1k
views
How to calculate a citric acid and trisodium citrate buffer?
I am trying to calculate how to prepare 500 mL of a citric acid (H3Cit) and trisodium citrate (Na3Cit) buffer with a pH = 4.5 and a total concentration of 0.1 M. I know that it is necessary to use the ...
- 71
1
vote
1
answer
70
views
An Index Poisoning Case Involving Dichlor and Carbonic Acid [closed]
I'm currently working an unusual case of poisoning, with Sodium Dichloro-S-Triazinetrione.
In my case, I need to know the expected reaction with carbonic acid.
I'm also curious if anyone could give ...
- 11
0
votes
1
answer
151
views
Problem understanding the rate of reaction of reversible reactions
Case 1:
$$\ce{CH_3COOH + NaOH<=>CH_3COONa + H_2O}$$
At equilibrium, there remain extremely small concentrations of the reactants (acetic acid and sodium hydroxide), and comparatively large ...
- 23
-1
votes
1
answer
285
views
How high does the base dissociation constant, Kb, have to be for a base to be considered "strong"?
I'm just confused as to how high the Kb constant / how low the Ka constant needs to be for a base to be considered a "strong base." The conjugate base of hydrogen phosphate ion, phosphate ...
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-3
votes
1
answer
78
views
Why do we need Equilibrium Constant as well as Acid Disocciation Constant? [closed]
I did the experiment to find out the dissociation constant of a weak acid using Henderson equation. However, after going through the theoretical part of the experiment, I am wondering why we need two ...
- 307
1
vote
2
answers
338
views
Effect of H+ concentration on equilibria
Considering the two equilibriums below, when the $[\ce{H+}]$ decreases, my book says that equilibrium \eqref{rxn:2} will shift to the left by a greater extent compared to equilibrium \eqref{rxn:1} ...
- 242
0
votes
0
answers
51
views
Which reaction is happening in the preparation of sulfuric acid through contact process?
I've read that in the preparation of $\ce{H2SO4}$ through the Contact process, on the absortion tower, the gas $\ce{SO3}$ is getting in contact with $\ce{H2SO4} (l)$ , because adding $\ce{SO3}$ to $\...
1
vote
1
answer
480
views
Acid dissociation constant calculated from the ionization percentage
The question goes like this:
An acid (HX) is 25% dissociated in water. If the equilibrium concentration of HX is $\pu{0.30 M}$, calculate the value of $K_\mathrm{a}$.
So I tried as follows:
if I ...
1
vote
1
answer
262
views
Strongest acid that can exist in water
Fundamentals of Biochemistry: Student Companion: Life at the Molecular Level[1] states that,
The strongest acid that can stably exist in aqueous solutions is $\ce{H3O+}$.
This is restated in the ...
- 27
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
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votes
1
answer
537
views
How to calculate Kp without knowing the volume? [closed]
I have the following chemical equation:
$$\ce{Sb2S3 + 3H2 <=> 2 Sb + 3H2S}$$
I have $\pu{1000 grams}$ of $\ce{Sb2S3}$ that reacts with $\pu{10 grams}$ of $\ce{H2}$ in a reactor at $\pu{713 K}$.
...
