# Tagged Questions

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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### Does a weak buffer solution still maintain a mostly steady pH if the acid or base load it has to buffer is small?

I need to buffer the $\mathrm{pH}$ of a solution to $3.0$ using a citrate buffer. I found a recipe to make a buffer solution that would use $82\%$ of $0.1\,\mathrm M$ citric acid (monohydrate) and ...
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### In equilibrium, if bonds are constantly being created and broken, where does the energy that does so come from?

I'm a student who recently learned about equilibrium and how it is not a state where nothing is made, but rather, a state where the product is decomposing at the same rate as the reactants are ...
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### Why is the equilibrium constant defined that way intuitively? for $\ce{ aA + bB <=> cC + dD }$

Suppose we have chemical equation $$\ce{ aA + bB <=> cC + dD }$$ then equilibrium constant is defined $$K=\frac{[C]^c[D]^d}{[A]^a[B]^b},$$ but why don't we define it as ...
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### Change of concentration in an equilibrium

I understand the fact that if you change the concentration of a pure solid or liquid in an equilibrium reaction, nothing happens because concentration = density which is constant in liquids and solids ...
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### What is the effect of adding HCl on a certain solution at equilibrium?

If we have $$\ce{CH3COOH + H2O <=> CH3COO- + H+}$$ what is the effect on acetate ions when adding each HCl and NaOH to the solution? (State why according to Le Chatelier's principle) ...
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### What are the methods used to measure the concentrations of these anions?

Chromate and dichromate anions has the following equilibrium in acidic solution: $$\ce{2CrO4^2- + 2H3O+ <=> Cr2O7^2- + 3H2O}$$ How can one experimentally measure the concentration of each ion ...
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### Alternate solution for finding concentration in equilibrium

This question is still waiting for a better alternate answer. If you can add it then your answer can be chosen as accepted I came across a question yesterday A container contains three gases. ...
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### What would Kp be if there is no gas reactant

What would $K_\text{p}$ be if there is no gas reactant but the reaction produces gas. I found something confusing: $$K_\text{p}=\frac{P_\text{gas product}}{P_\text{gas reactant}}$$ If there is no gas ...
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### Resultant temperature of mixture

**Question: ** There are 2 flasks of equal volume, connected by a narrow tube of negligible volume, filled with nitrogen gas. When both are immersed in boiling water, the gas pressure inside the ...
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### How can collission theory of chemical reaction and Law of mass action be connected?

Collision theory is a theory that qualitatively explains how chemical reactions occur and why reaction rates differ for different reactions The collision theory states that when suitable ...
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### Acidity of HCl in Acetic Acid

A question asked to find the pKa of $\ce{HCl}$ in acetic acid. The equation of $\ce{HCl}$ disassociating in water is: $$\ce{HCl + CH3COOH \leftrightharpoons CH3COOH2+ + Cl-}$$ I predicted that the pKa ...
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### Titration Question

Problem: A solution of an unknown weak acid of unknown concentration was titrated with a solution of a strong base of unknown concentration. During the titration, the pH after adding $2.00$ mL of the ...
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### Charge:ionic radius ratio

can someone please explain what the charge to ionic radius ratio of a metal hydroxide would mean for its solubility. As in would there be a trend e.g. as the ratio gets larger the solubility product ...
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### Equilibrium saturation/depostion rate calculation

I found the Knudsen/Langmuir equation for calculating the sublimation rate of a solid. If I have a closed system, once the vapor reaches the saturation pressure, the solid will continue sublimating ...
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### How to prove that the forward and reverse reactions have the same rate at equilibrium?

I was trying to answer a question from Zumdahl and Zumdahl's Chemistry textbook which asks me to show that the rate constant K is related to the forward and reverse reaction constants: ...
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### How to know when subscripts refer to charges or not

My question is very easy. Sometimes to determine to charge of a compound you multiply the charge by the number of ions you have of that element. But sometimes it seems as if you don't do it this way. ...
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### Why are Kc and Kp interchangeable in the free energy-equilibrium equation? [duplicate]

In this equation that relates Standard free energy and the equilibrium constant: $\Delta Gº=-RT \ln K_{eq}$ My textbook (and my teacher) say both $K_p$ (constant related to pressure) and $K_c$ ...
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### Possible approximations in complex equilibrium

If I have the following equilibrium: $$\ce{Cu^2+ + 4NH3 <=> Cu(NH3)4^2+}$$ Given an initial concentration of $\ce{Cu^2+}$ ($C_\ce{Cu}$) and an initial concentration of ammonia $C_{NH_3}$, the ...
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### Why is the Haber process carried out at such high temperatures?

On a large scale, ammonia is prepared via the Haber process: $$\ce{N2(g) + 3H2(g)->2NH3(g)} \qquad \Delta _\mathrm{f}H^\circ = -46.1~\mathrm{kJ \cdot mol^{-1}}$$ The optimum conditions for the ...
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### What is meant by a reaction favours one side?

I frequently see in textbooks the phrase, a reaction favours the left/right side, but don't know what this means. Does this mean the equilibrium shifts to one side?
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### What are the correct equilibrium arrows?

I was recently subject to some atrocious teaching. One of the gems that found me was the equilibrium arrow usage. I am accustomed to write $\ce{<=>}$. Yet, the entire class had to use ⇆ ...
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### Enthalpy change and equilibrium

I don't understand why enthalpy change won't change at an equilibrium? The reason I ask this is because of this question: At first I thought the answer is C, but I realised that the amount depends ...
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### Why does a dynamic equilibrium exist?

We know that at equilibrium Gibbs free energy is minimum. We also know that at equilibrium both forward and reverse reactions occur simultaneously, and we also know that for a reaction to be ...
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### Active mass,Pressure and concentration

The concentration is connected to the activity via $$a(\ce{A})= \gamma_{c,\ce{A}}\cdot{}\frac{c(\ce{A})}{c^\circ},$$ where the standard concentration is $c^\circ = 1\:\mathrm{mol/L}$. At reasonable ...
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### Why at constant pressure and temperature Gibbs energy change of a process can be negative?

$dG < 0$, for a spontaneous reaction at constant Temperature $T$ and Pressure $P$, this means that at contant $T$ and $P$, $dG$ can be negative $dG = VdP -SdT$, this means that at constant $P$ ...
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### Formation of a stable hydrate

Question: Which of the following does not form a stable hydrate? I think they mean nucleophilic addition of water. For compound (C), on reaction with water, the product formed is The ...
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### Which has maximum entropy

Which state has a higher entropy — the liquid–gas equilibrium or the gaseous state? I have learned that at equilibrium the entropy is maximised. But I also learned that the gaseous state has the ...
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### Ostwald Law of dilution makes no sense

According to wikipedia the Ostwald's dilution law says that for a weak acid $K_{d}={\cfrac {[A^{+}][B^{-}]}{[AB]}}={\frac {\alpha ^{2}}{1-\alpha }}\cdot c_{0}$ when I read the derivation of it ,I ...