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The state in which both reactants and products are present at concentrations which have no further tendency to change with time.

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8 views

How does Borax Solution act as a buffer?

What type of buffer is it? If it's a Weak Acid-Conjugate Base type of buffer, what is the weak acid and conjugate base?
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0answers
11 views

Finding equilibrium concentration

Plz answer 233 question its related to physical equilibrium
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0answers
14 views

Does the pH scale ranging from 0 to 14, changes at different temperatures ? [on hold]

At 4 5 degree Celsius pH of a solution is 7 what is the pH range? Is it acidic or basic?
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1answer
17 views

Equilibrium expression for dissolution of carbon dioxide

I was asked to give the equilibrium expression for: $$\ce{CO2(aq) + H2O(l) <-->H2CO3(aq)}$$ As water is a liquid and a solvent here, it shouldn't be included in the expression, hence I wrote: ...
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0answers
16 views

Equilibrium question [closed]

6.9 grams of ethanol and 4.7 grams of ethanoic acid were kept at a temperature of 298K until equilibrium was reached. 4 grams of ethanol were found to remain. In another experiment, 13.8 grams of ...
-1
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0answers
43 views

Why does sulfuric acid form sulfate compounds in acid-base reactions?

I read that since sulfuric acid is diprotic, if it is dissolved in water the reaction with a greater acid dissociation constant is the one which produces hyronium ions and hydrogensulfate ions. Where ...
1
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0answers
71 views

Color change of aqueous ferric salt when reacted with phosphate

I have a question about an equilibrium system: $$\ce{Fe^3+ (aq) + SCN-(aq) <=> [Fe(SCN)]^2+ (aq)}\\ \text{(yellow)} \quad \text{(colorless)}\quad \qquad\text{(red)}\qquad\quad$$ The question ...
-1
votes
1answer
26 views

What is the meaning of K in the thermodynamic equation for equilibrium constant?

I just studied the formula for equilibrium constant in thermodynamics. But when an equilibrium is established $\Delta G$ is always $0$ as told by my teacher. Then $k$ has to be always $1$ whenever an ...
2
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1answer
66 views

How is silver chloride more soluble in brine than water?

I heard that: Silver chloride is more soluble in very concentrated NaCl solution (brine) than in pure water. Is it true? I mean won't the common ion effect operate? Or may be this is due to some ...
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0answers
17 views

Why are Txy diagrams curved for dew point and bubble point?

What is the reason behind drawing dew point curve and bubble point curve as curved (and dew point curved outwards and bubble point curved inwards) for Temperature vs Composition Phase Diagram as per ...
-1
votes
1answer
23 views

Finding the error in attempting the equilibrium question through isotherm equations

Consider the partial decomposition of A as: $$\ce{2A(g) <=> 2B(g) + C(g)}$$ At equilibrium $\pu{700 ml}$ of gaseous mixture contains $\pu{100 ml}$ of gas C at $\pu{10 atm}$ and $\pu{...
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1answer
35 views

Why is the equilibrium constant unaffected by a change of the initial concentration?

In my class, it was taught that the equilibrium constant does not vary with the intial concentration of the reactants? Why is it so?
2
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0answers
13 views

To which all factors chemical equilibrium is directly proportional to? [closed]

The equilibrium constant is directly proportional to the concentration. why it is so? Is chemical equilibrium dependent on temperature and other such factors? Then why we only focus on concentration?
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2answers
43 views

Why is the concentration of protons equal to the concentration of a strong acid?

First, I know that strong acids are assumed to dissociate completely in water, so that the concentration of $\ce{H+}$ which they provide equals their concentration. What I am asking for is not the ...
-1
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0answers
54 views

Is equilibrium ever possible in an open system?

I have read in a few places (Wikipedia, school textbook) that "An open system can never reach equilibrium." There is the argument that if one of the products of a reaction is gaseous, it may escape, ...
1
vote
1answer
52 views

Buffer made of salts of polyprotic acid: reactions

I was trying to make a buffer with $\ce{K2HPO4}$ to use it in a bacterial culture. If I use $\ce{K2HPO4}$ I think I have to add $\ce{KH2PO4}$. I am trying to think it writing the equations of the ...
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votes
3answers
57 views

Titration of Na2CO3 against HCl

$\pu{25mL}$ of $\pu{0.125M}$ $\ce{Na2CO3}$ is titrated with $\pu{0.100M}$ $\ce{HCl}$. Given that $K_{a1} = 4.3\times10^{-7}$ and $K_{a2} = 4.8\times10^{-11}$ for the diprotic acid $\ce{H2CO3}$, ...
1
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0answers
29 views

Difference between Henry constant and equilibrium constant

According to wikipedia, Henry constants define the ratio between the aqueous and gas fraction of a chemical species at equilibrium. Lets consider Henry constants H in atm.L.mol-1 such that $[C]_{g} = ...
2
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0answers
41 views

How to without calculations understand the liquid-liquid extraction efficiency?

I'm asking myself this question for a very long time and I haven't found a simple an good explanation yet for the fact that it's better (if you want to clean them) to wash your hands two times with ...
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0answers
21 views

Do reactions in equilibrium always revert to one colour?

I'm trying to wrap my head around the concept of equilibrium and I have a question relating to colour. Suppose there is a chemical reaction: A --> B Also assume that A is white whilst B is black, ...
-1
votes
1answer
39 views

Rate of a reaction [duplicate]

We know that the rate of a reaction $\ce{aA + bB -> cC + dD}$, the rate of the forward reaction is given by $r_\mathrm f = k_\mathrm f[\ce A]^p[\ce B]^q$ where $ a\neq p$ and $ b\neq q$ according ...
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0answers
19 views

Boudouard Equation

I have a doubt: I'm working with the Boudouard Equation (2CO=CO2+C) and I know that the equation is exothermic when Carbon is produced so that it is favored by Low Temperatures. The question is: when ...
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0answers
62 views

Why does a EMF measurement deliver standard state values?

In the literature one can often find the following equation for the determination of standard Gibbs Energies of Formation with emf measurements: $$\Delta_f{G}^\circ = -zFE$$ I don't understand why ...
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0answers
45 views

Is the concentration of water included in the acid disscociation constant? - Wikipedia confuses me

I refer to the following wikipedia article https://en.wikipedia.org/wiki/Acid_dissociation_constant Header paragraph: Equilibrium constant. First the equilibrium constant is given in terms of ...
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votes
1answer
49 views

Why don't buffer solutions return to equilibrium?

Suppose I want to make a buffer solution in any of the three ways possible with dihydrogen phosphate as my weak acid. In the first way, a certain ratio of the weak acid and its conjugate base are ...
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2answers
45 views

Equilibrium for very small amounts of reactants

Is there any difference in the concept of equilibrium when it comes down to dealing with extremely small amounts of reactants? Say we have $$\ce{A + B <=> C + D}$$ and $K_c$ is $100,000$. If ...
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2answers
60 views

How does the equilibrium shift when concentration of reactant and product are increased simulatenously

Before answering my question, take a look at this example $$\ce{2NOCl <=> 2NO + Cl2}$$ Let's suppose I have 2 mol/l $\ce{NOCl}$, 2 mol/l $\ce{NO}$, and 1 mol/l $\ce{Cl2}$ in a closed system. ...
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1answer
33 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 ...
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0answers
44 views

Is it necessary to write water as a reactant in the acid dissociation equilibrium?

If I wish to write out the acid dissociation equilibrium, is it necessary to write in the water as a reactant, or does it suffice to write the following? $$\ce{HA <=> H+ + A-}$$ Is it alright ...
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0answers
26 views

Limiting factor on Belousov-Zhabotinsky reaction

In the thin film Belousov-Zhabotinsky reactions (popular on Youtube/in chemistry demonstrations), concentric rings of different colors propagate across a petri dish for minutes to hours as the ...
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0answers
53 views

Reason for formation of bubbles at boiling point [duplicate]

As I understand it, boiling takes place when the saturated vapour pressure equals to the atmospheric pressure. But, why does the vapour pressure need to be equal to the atmospheric pressure for ...
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0answers
75 views

Why do we use hydrochloric acid in preparation of complex between salicylic acid and Fe3+ ions

In a lab, we had to prepare a complex by reacting ferric ammonium sulfate and salicylic acid. We prepared $500~\pu{mL}$ of $1.0~\pu{mM}$ salicylic acid. Instead of water, we used $5\ \pu {mL}$ of ...
1
vote
1answer
30 views

Heat generation in exothermic reactions [duplicate]

Im thinking specifically of N2 + 3 H2 ⇌ 2 NH3. Its an exothermic reaction, therefore heat is generated. Im trying to understand how Chateliers principle interacts with this reaction. I understand that ...
-1
votes
2answers
40 views

Calculate pH of a mixture of a strong base and acid. Knowing only the pH, wt/v%, and volume of both solution. [closed]

Title explains all. I have been stuck on this for an hour and for some reason cannot understand it. I have tried to do an ICE table but get stuck halfway as I do not know whether I would use the w/v ...
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0answers
34 views

The equilibrium between zinc and zinc ions

In order for the equilibrium of zinc ions and zinc to be set up, the forward and backward reaction have to occur simultaneously, such that eventually the rate of the forward reaction will be ...
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1answer
65 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 ...
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0answers
37 views

Why is $K_w = [\ce{H3O+}][\ce{OH-}]$ constant? [duplicate]

I have just learned that for any solution, the product of the concentrations of hydrogen ions and hydroxide ions is a constant value. Why is this, especially for anything that isn't just water and $\...
4
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0answers
69 views

Computing the turbulent flame length

There is a problem I found online for practice that I cannot solve: Problem Methane, $\ce{CH4}$, emerges from a $1\ \mathrm{cm}$ diameter nozzle at a rate of $120\ \mathrm{cm^3/s}$ and a mole ...
2
votes
1answer
59 views

Why are the concentrations in the equilibrium constant multiplied? [duplicate]

$$\alpha\,\mathrm{A}+\beta\,\mathrm{B}+\cdots\rightleftharpoons \rho\,\mathrm{R}+\sigma\,\mathrm{S}+\cdots$$ The equilibrium constant for this reaction can be calculated using the following formula: $...
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1answer
42 views

What does it mean for an equillibrium to move? [duplicate]

Le Chatelier's principle was described to me as: If a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium moves to counteract the change. I do not understand ...
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votes
1answer
33 views

Ionproduct of Water [duplicate]

The ionproduct of pure water is well known to be $$ K_{\rm W} = \left[ {\rm OH^-} \right] \left[ {\rm H_3O^+} \right] = 10^{-14} $$ at some standard conditions (I think 25°C). However having some ...
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1answer
94 views

How to calculate pH of the Na2Co3 solution given ambiguous Ka values

This is the exact question i faced on exam. Calculate the 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 $\ce{Na2CO3 -&...
1
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0answers
27 views

Is there a thermodynamic explanation for how a substance behaves based on its pKa and the solution’s pH?

If the pH of the solution is lower than the pKa of the compound, then the compound will be protonated, because pH is a measure of the concentration of protons, and low pH means a high proton ...
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2answers
81 views

What is the relationship between the constant of equilibrium (Kc) and the position of equilibrium? [duplicate]

I understand that the constant of equilibrium is a ratio of the concentration of the products to the reactants and that this value allows one to estimate whether the position of equilibrium lies to ...
5
votes
2answers
173 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 ...
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votes
1answer
28 views

Is it possible to calculate the Kc for an irreversible reaction? [closed]

Is it possible to calculate the Kc for an irreversible reaction? For instance, can we Calculate the $K_c$ for: $$\ce{NaCl + AgNO3 -> NaNO3 + AgCl}$$
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0answers
40 views

How does association within vapor or dissociation within liquid affect the ideal nature of a binary solution?

As I understand, when there is positive deviation of a binary solution from Raoult's Law, the equilibrium partial pressure curve approach ideality (i.e a straight line dependence of equilibrium ...
0
votes
1answer
127 views

Finding equation of line of the P-T graph for a gas dissociation reaction

Gas A (1 mol) dissociates in a closed rigid container of volume 0.16 lit as per following reaction. $$\ce{2A (g) -> 3B (g) + 2C (g)}$$ If degree of dissociation of $\ce{A}$ is 0.4 and ...
1
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0answers
51 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 ...
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1answer
51 views

Chemical equilibrium constant problem

In a equilibrium reaction $\ce{CO {(g)} + H2O {(g)} <=> CO2 {(g)} + H2 {(g)}}$, initial concentrations of $\ce{CO}$ and H2O are equal and are 0.3 mol/dm3. What is the equilibrium constant of ...