Questions tagged [equilibrium]

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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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 ...
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In which of the following mixing of 1N of acid and 1 N of base results in increase in temperature [closed]

20ml of acid + 30 ml of base 10 ml of acid + 40 ml of base 24 ml of acid +25 ml of base 35 ml ofacid +25 ml of base
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What is 'spray foam' or 'expanding foam'?

At the wikipedia are: Spray foam (expanding foam in the UK) is a chemical product created by two materials, isocyanate and polyol resin, which react when mixed with each other and expand up to 30-60 ...
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For a system in equilibrium, ΔG=0 , under conditions of constant______. A.Temperature and pressure. B.Temperature c) energy ,volumed)pressure,volume [closed]

Can you please solve this MCQ. I am confused because I feel pressure temperature and volume all will be constant
Chandrashekhar's user avatar
3 votes
1 answer
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How can a Michaelis–Menten formalism be used when enzyme concentration isn't constant?

I understand that $V_\mathrm{max} = k_3[\ce{E}]_0$ in ordinary Michaelis–Menten (MM) kinetics. According to the lecture notes provided by my university (I don't believe they are available online), ...
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2 votes
1 answer
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Does solubility product dictate predominant precipitate from the solution with several ionic compounds?

While removing temporary hardness through boiling, magnesium bicarbonate will give $\ce{Mg(OH)2}.$ $\ce{Mg(OH)2}$ predominates over $\ce{MgCO3}$ as the solubility product $K_\mathrm{sp}$ of $\ce{Mg(OH)...
Avaneesh B's user avatar
3 votes
1 answer
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Calculation of Reaction Extent as a Function of Pressure and Temperature: Issue with Activity-Based Approach

I'm working on modeling reactions involving combinations of hydrogen (H), nitrogen (N), and strontium (Sr) elements. I've obtained the temperature-dependent Gibbs free energy of formation, enthalpy, ...
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Understanding the relationship between Delta G and Kp, Kx and Kc

**Upon reading the chapter about equilibrium from my physical chemistry book, I was convinced that ΔG=−RTln(Kp)(1) and that Kp=Kx(P∑v)(2) where Kp is the equilibrium constant with respect to pressure ...
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How does cell potential change with temperature for positive enthalpy and negative entropy?

A recent United States National Chemistry Olympiad question asked: A certain voltaic cell has a standard cell potential that increases with increasing temperature. Which best explains this ...
unstable's user avatar
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Solubility of lead carbonate

Lead nitrate reacts with sodium carbonate to form lead carbonate, if sodium carbonate is in excess will the white precipitate of lead carbonate dissolves ? Like in lead nitrate reaction with excess of ...
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Common Ion Effect - Cl- disappeared more than it existed

I had an experiment of Common Ion Effect I have dissolved 35.92g of NaCl(s) in 100ml water (which is saturated) And I have added 10ml of 12.0M HCl. I have checked NaCl was precipitated. NaCl was 0.614 ...
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Calculation of Kc

Gaseous hydrogen and gaseous iodine react together to form hydrogen iodide. H2 + I2 ⇌ 2HI The graph shows how the amount of hydrogen iodide varies with time in a 1.00 dm3 container. The initial ...
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How can equilibrium constant be derived by irreversible reaction?

I am solving the example from the book [Essentials of Chemical Reaction Engineering, Chapter 3, P3-12B] and finding out a contradictive point. "The rate law for the A->B reaction was obtained ...
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Reversible and irreversible reactions [closed]

I searched that an reversible reaction can be made irreversible by removing its product. I am wondering if catalysts can help produce the same effect. And I'd also like to know, if actually an ...
Chemistry student's user avatar
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How is it even possible that vapour pressure of liquid and vapour of solid are equal at freezing point? [duplicate]

My text book states The freezing point is defined as "the temperature at which the vapor pressure of the substance in its liquid phase is equal to its vapor pressure in the solid phase" Also ...
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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, ...
Aurelius's user avatar
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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,...
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1 answer
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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 ...
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Why does balancing the oxidation of dichromate(VI) to chromium(III) require six iron atoms?

The problem: Balance the following chemical equation using oxidation numbers: $$ \ce{Fe^2+ + Cr_2O_7^2- -> Fe^3+ + Cr^3+} $$ What I have tried: $$\ce{\overset{+II}{Fe}^{2+}(aq) + \overset{+VI}{Cr}...
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Determine equilibrium stability transition of a reaction (function of temp and concentrations)

I am trying to calculate and plot the stability of $\ce{Fe3O4 - FeS2}$ based on the chemical equation: $$ \ce{Fe3O4(s) + 6SO2(g) + 16CO(g) -> 3FeS2 (s) + 16CO2(g)} \tag{1} $$ I want to plot the ...
learning_physics's user avatar
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Really though, why can't a equilibrium manifest in a open system?

What my teacher said today: "Equilibrium is not attainable in an open system because then there the concentrations of the species in the system are undergoing continuous change, thus the reverse ...
moon river's user avatar
2 votes
2 answers
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My textbook writes hydronium ion as [H(H2O)]+, is this correct? [closed]

[...] Thus, it bonds to the oxygen atom of a solvent water molecule to give trigonal pyramidal hydronium ion, $\ce{H3O^+}$ $\ce{\{[H (H2O)]^+\}}$ (see box). In this chapter we shall use $\ce{H^+(aq)}$ ...
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Why doesn't sodium bicarbonate dissolved in water spontaneously effervesce when carbonic acid does?

It's well known that if you put carbonic acid $\ce{H2CO3}$ into water it will dehydrate into carbon dioxide $\ce{CO2}$ and water $\ce{H2O}$. Indeed this is how modern fizzy drinks generate their fizz. ...
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Bodenstein Hydrogen Iodide equilibirum experiment query

This text says that the same amount of HI was formed during the bulbs' time spent in the thermostat baths, regardless of the varying initial amount of HI each bulb contained. Is this true? I always ...
moon river's user avatar
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Why does balancing the reduction of dichromate(VI) to chromium(III) require four water molecules among the products?

Problem Balance the following chemical equation using oxidation numbers: $$\ce{Cr2O7^2–(aq) + HNO2(aq) –> Cr3+(aq) + NO3–(aq)}$$ Solution (in Swedish) $$\ce{\overset{+VI}{Cr}_2O7^2–(aq) + H\...
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Isoelectric Point

How do we derive the formula of isoelectric point? pI=(pKa1 + pKa2)/2 I read that isoelectric point is defined as the pH at which degree of protonation in amino group is same as degree of ...
Priyanshu Kumar's user avatar
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Bancroft's point

In the last problem (Problem 10.43) within the problem section of Chapter 10 in "Introduction to Chemical Engineering Thermodynamics" (J.M. Smith, H.C. Van Ness, M.M. Abbott, McGraw-Hill, ...
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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 ...
Thecoder001's user avatar
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1 answer
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Inconsistency in between Nernst Equation and Gibbs Free Energy Equation [closed]

Part 1 - Derivation of the Gibbs Free Energy Equation: [copied from this] Using the fundamental equations for the state function (and its natural variables): \begin{align} \mathrm{d}G &= -S\...
Asmit Karmakar's user avatar
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3 answers
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How salt helps to melt ice even when there is no dynamic equilibrium between water and ice?

I am a high school student and I am confused about freezing point depression. We say that when in winter's it gets even colder than normal freezing point Temperature then we use solute to melt ice ...
Virender Bhardwaj's user avatar
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3 answers
238 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 ...
QuantumHamster's user avatar
1 vote
3 answers
215 views

Unattainable equilibrium

I read a question on a textbook that asked: For the reaction $$ \ce{CaCO3(s) \rightleftharpoons CaO(s) + CO2(g)} \tag{1}$$ determine whether or not a mixture of $\ce{CaCO3(s)}$ and $\ce{CO2(g)}$ at a ...
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Temperature dependence on the feasibility of an equilibrium

If we consider a reaction A + B ⟶ C + D, with $\Delta$S $>0$, then regardless of whether $\Delta$H is positive or negative, increasing the temperature will make $\Delta$H - T$\Delta$S more negative,...
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2 votes
2 answers
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Multiple equilibria

I was reading about multiple equilibria reactions and can't quite comprehend some things. Suppose we have two reactions: \begin{align} \ce{A + B &<=> C + D},& K_\mathrm{eq} &= 10^{20}...
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Derivation of general binding equation (macromolecule with multiple binding sites)

So the last days I'm stuck at trying to solve the an equation - but I just can't (see the screenshot below. So the idea is that you have a receptor or enzyme with multiple binding sites for a Ligand (...
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2 answers
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Boiling point, pressure, and Gibbs free energy

The water boiling process can be represented by the equation: $$ \ce{H2O(l) → H2O(g)} \tag{1} $$ Since free energy depends on pressure $$ \left(\frac{\partial G}{\partial P}\right)_T = V \tag{2} $$ ...
Marijus Klp's user avatar
1 vote
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Van't Hoff graph, the Ka is increasing at a slower rate as temperature increases

I understand the exponential relationship between Ka and temperature, but I had expected it to be curving upwards(because of the $e^x$), and not like a log graph (where y-values increases slower for ...
Metron's user avatar
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1 answer
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Does Hess' law in standard conditions involve consuming all reactants?

The standard free energy change for equilibrium problems is relative to both reactants AND products starting at 1 molar. Hess’s law takes the sum of the values for products minus the sum of the values ...
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How to convert the uncertainty of my pH probe to the uncertainty of my Ka value

Literally the title. So basically I performed numerous titrations with ethanoic acid sodium hydroxide. I got the full pH curve, and subsequently found the Ka Value of the ethanoic acid. Now here is ...
Metron's user avatar
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Are catalysts considered when assigning type of chemical equilibrium?

So I have very short doubt that whether catalysts are considered when we say that an equilibrium is homogeneous or heterogenous, like in an aqueous equilibrium with only aqueous reactants and products ...
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Van't Hoff Equation isolating for K2

So I wanted to find the theoretical Ka values of acetic acid from 25-65 degrees at 10 degree increments: 25, 35, 45, 55, 65. I know that the dissociation of acetic acid is endothermic, and when I ...
Metron's user avatar
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2 answers
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Why does a small decrease in [ATP] cause a large increase in [AMP]

I was wondering how the reaction catalysed by adenylate kinase and its equilibrium of approximately 1 leads to [AMP] changing greatly with a small change in [ATP]. The below information was provided ...
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4 votes
1 answer
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Calculating partial pressure: Difficult cubic equation in bulky Chemical Equilibrium numerical

The problem, which I found in a popular book for Physical Chemistry, written by Neeraj Kumar, is fairly simple, being simply 2 equations and 2 variables, yet its simplification is a nightmare. $\pu{5 ...
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Why isn't the unit of rate constant for any reaction always per second?

It is formally agreed upon that $K_{eq}=\prod_{j}a_j^{\nu_j}$ where $\nu_j$ is stoichiometric coefficient of species $j$ (negative for reactants and positive for products). This equation results in ...
megamonster68's user avatar
3 votes
3 answers
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Evaluating the density of a gas equilibrium mixture

I'm a beginner in chemistry (first year uni course) and I have this exercise that I need some help with. I don't really know where to start so for now. I've tried random approaches to see what works ...
Dhimitri Lici's user avatar
-5 votes
1 answer
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Are buffer solution and acidic buffer different? [closed]

I have studied that acidic buffer is a type of buffer solution but the definition of buffer solution says that it's a mixture of a weak acid and its conjugate base or a weak base and its conjugate ...
yyzr's user avatar
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7 votes
0 answers
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Metal hydrolysis and equilbrium constants from stability constants

Problem: I want to create minimum solubility plots for a series of metal hydrolysis species against pH (below). But I cannot reconcile literature stability constants and equilibrium constants. Context:...
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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 ...
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1 answer
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Mathematics behind the graph between Gibbs energy and extent of reaction

When the graph between Gibbs energy and extent of reaction is plotted, such a curve is obtained: I am unable to understand how we got to the concavity of this graph (which can also be seen as the ...
calcandquant's user avatar
1 vote
0 answers
31 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 ...
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