Questions tagged [equilibrium]

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

Filter by
Sorted by
Tagged with
2
votes
0answers
47 views

Why does the pressure equilibrium constant exist? [duplicate]

Since $K_c$ can already be used for calculating the equilibrium constant for a reaction involving gases, but $K_p$ cannot be used for calculating the equilibrium constant for a reaction involving ...
3
votes
1answer
309 views

Why isn't standard Gibbs free energy always zero?

I read in my textbook that one of the standard conditions we should use when calculating the standard Gibbs free energy is having a concentration of 1 M of all the reagents and the products in the ...
6
votes
1answer
211 views

Apparent contradiction in the type of deviation of an ethanol-water mixture

For a mixture of $\ce{EtOH}$ and $\ce{H2O}$: $\Delta H_{\text{mix}} < 0$ (exothermic) and $\Delta V_{\text{mix}} < 0$ (volume contraction). This means that the unlike interactions are stronger ...
15
votes
1answer
1k views

Can a zeroth order reaction be reversible?

After recently studying about chemical equilibrium, I was convinced that the forward and backward reaction rates meet each other at equilibrium. However thinking about zeroth order reaction annoyed ...
1
vote
2answers
227 views

Buffer Solution Problem (Acid/Conjugate Base)

To create a buffer mixture, I understand that mixing an equal concentration of a weak acid and it's salt (conjugate base) will form an acidic buffer. However, why is it that when $\pu{25 cm^3, 9.100 ...
2
votes
2answers
243 views

reaction coordinate, kinetics, equilibrium in example

In this special reaction coordinate diagram with two reaction mechanisms, I tried to analyze it in two other ways, one with kinetics, another with equilibrium. A. kinetics, I tried to find reaction ...
1
vote
1answer
71 views

Confusion about the ICE table

Calculate the pH of a $\pu{2M}$ $\ce{H_3PO_4}$.Calculate the equilibrium concentrations of $\ce{H_3PO_4 , H_2PO_4^{-} , HPO_4^{2-}}$. First equation: $\ce{H_3PO_4 <=> H^{+} + H_2PO_4^{-}}\ \ \...
0
votes
1answer
54 views

Calculating the change in pH upon diluting an acid

What volume of water is added to $\pu{400 ml}$ of $\ce{HCL}$ solution so that the pH of the solution increases by 1 unit This is how far i went but the answer says $\pu{1000 ml }$ where am I wrong is ...
0
votes
1answer
159 views

How to justify this contradiction in acid-base equilibrium of methanol and water? [duplicate]

Let's talk about the following compounds - water and methanol. We know that methanol is slightly more acidic than water, because water's ability to donate a proton as an acid is reduced due to ...
5
votes
2answers
655 views

Why does increasing the pressure cause ice to melt more?

This question was given under chemical equilibrium. Why does increasing the pressure on this system cause ice to melt more? $$\ce{H2O(s) <=> H2O(l)}$$ I'm pretty sure this has to be ...
1
vote
0answers
187 views

Henderson-Hasselbalch approximation

The Henderson-Hasselbalch approximation gives us a method to approximate the pH of a buffer solution. The basic equation is as follows: $$\mathrm{pH} \approx \mathrm{p}K_\mathrm{a} + \log\dfrac{\ce{[...
3
votes
1answer
91 views

Are my intuitions about how batteries work right? [closed]

Being really fascinated by how electricity actually works, I started studying batteries. I initilally understimated the complexity of this apparently-simple objects, and thorugh studies and researches ...
0
votes
1answer
131 views

Variation of equilibrium constant

In an exothermic reaction, the value of equilibrium constant increases with the rise of temperature because, $\Delta H < 0$ ( exothermic reactions) $\Delta G = \Delta H - T\Delta S$ Now if $\...
0
votes
1answer
1k views

Numerical on change in degree of dissociation wrt pressure

The degree of dissociation of $\ce{PCl5}$ is 0.4 at 2 atm pressure and T kelvin. At what pressure will degree of dissociation of $\ce{PCl5}$ be 0.6? Taking the degree of dissociation as 0.4, I got ...
1
vote
2answers
268 views

Is the new equilibrium total pressure of this equilibrium reaction always more than its initial total pressure?

In the case of the reaction $$\ce{2NO2 <=> N2O4}$$ at equilibrium and considering Le Chatelier's principle, if we add more $\ce{NO2}$, the pressure of $\ce{NO2}$ will increase acutely and then ...
2
votes
1answer
383 views

Predicting Ka/Kb values using values for solubility in water

Given that $K_\mathrm{a}$ values are determined by the position of equilibrium for a species such as $\ce{HCl}$ where $K_\mathrm{a} = \ce{\frac{{[H^{+}]}{[Cl^{-}]}}{[HCl]}}$, I was wondering whether ...
1
vote
1answer
207 views

Shift in the position of equilibrium by a catalyst to favor the forward reaction

We were looking at the factors that affect dynamic equilibrium today. The teacher explained how catalysts only affect the rate at which dynamic equilibrium is achieved, and not its position. My ...
0
votes
1answer
2k views

Calculating Kp in two different ways

The degree of dissociation of $\ce{NH3}$ at $\pu{1 atm}$ is 20 % as follows: $$\ce{2NH3 <=> N2 + 3H2} $$ I follow two ways but end up with two different answers. Here, I assume that ...
1
vote
1answer
486 views

Equilibrium change in sealed container

Question: Decreasing the product's concentration seemed to follow the logic of Le Chatelier's principle, so a decrease in volume will force the reaction to the left to increase the pressure (...
1
vote
1answer
74 views

Neutral anions in salts and strong acids are similar - is it a coincidence? [closed]

Recently I was studying salts and my professor provided a list of anions which are considered neutral in salts (that is, they do not change the $\mathrm{pH}$ of an aqueous solution when added as a ...
1
vote
2answers
105 views

Clarification in a particular application of Le Chatelier principle [closed]

There is something I don't understand about a particular application of the Le Chatelier principle. The following system is in equilibrium: $$\ce{CH3COOH + H2O <=> H3O+ + CH3COO-}$$ If I add ...
0
votes
1answer
92 views

Equilibrium, temperature change, and prediction in constant volume

When it's constant volume, change of $T$ (Kelvin temperature) in a reaction equilibrium system won't change the volume. Let's say we change the temperature from $T$ to $2T$ of this reaction at ...
2
votes
1answer
71 views

Relative fraction of population of different enzyme conformations, knowing the rate constants

Say we have an enzyme that has multiple structural conformations, say A, B, C and D. Additionally, we say that the enzyme must go through all conformations, to get to one end to the other, i.e. $$\...
5
votes
1answer
418 views

What is the meaning of 'mass action'?

I understand the statement of 'Law of mass action', but I don't understand clearly what 'mass action' means. I investigated it and found the following descriptions. The law was originally suggested ...
1
vote
0answers
64 views

Is chemical equilibrium possible at any temperature and pressure?

Consider the chemical reaction ${\rm Na+Cl\to NaCl}$ by mixing ${\rm Na}$ with ${\rm Cl}$ (or by mixing ${\rm NaOH}$ with some acid). This process is exothermic while the reverse ${\rm NaCl\to Na+Cl}$ ...
1
vote
0answers
77 views

What causes both components of a binary gas mix to condensate at the same time for a given composition

Okay, so recently I encountered the temperature - mole fraction diagrams for binary vapour-liquid equilibrium. For now, I only consider two-component systems where the components are very similar and ...
-5
votes
2answers
52 views

The Ionization of Water [closed]

When we put $\ce{HCl}$ in a container of water and let's say that the concentration we put is $10^6$ molar. Let me understand this calculation: $[\ce{OH-}]=x$ $[\ce{H+}]=10^6+x$ $x(10^6+x)=10^{-14}$ ...
2
votes
1answer
2k views

Why does adding water to a saturated solution increase the number of ions present in the solution?

In my book, it is stated that when some water is added to a test tube having a saturated $\ce{Ag2SO4}$ solution, with its solid at equilibrium, the number of $\ce{Ag}$ ions in the solution increases. ...
-1
votes
1answer
4k views

Find the half equivalence point

How to find the half equivalence point knowing the pH, molarity, titrant added at equivalence point? This a fairly straightforward and simple question, however I have found many different answers to ...
0
votes
1answer
40 views

Volume of NaOH needed to precipitate copper(II) but not calcium

I have $\ce{NaOH}: C = \pu{0.1M}, V_{\ce{NaOH}}$ that I want to progressively add in a solution (in water) of: $$\begin{align} \ce{Cu^{2+}}&: \pu{0.01M}; & K_\mathrm{sp} &= 10^{-18.6} \\ \...
0
votes
1answer
949 views

Chemical equilibrium and stoichiometry

In reactions that go until the end the stoichiometric number indicates the exact amounts of reactants and products you will get. However, this is not the case in equilibrium reactions and you will get ...
0
votes
1answer
409 views

What happens if you add NaCl during the neutralization reaction between HCl and NaOH?

In class, I was taught that $\ce{NaOH}$ and $\ce{HCl}$ react completely (no equilibrium). I get the equation: $\ce{NaOH + HCl -> H2O + NaCl}$. However, if I were to add a lot of $\ce{NaCl}$ to the ...
2
votes
0answers
267 views

Electrodes involving sparingly soluble salts (Electrodes of the second kind)

Consider the sparingly soluble salt, $\ce{AgI}$ ($K_\text{sp} = 8.52\times10^{-17}$) and a silver electrode (Standard Reduction Potential = $\pu{0.799V}$). $\pu{0.02L}$ of $\pu{0.001M}~\ce{KI}$ ...
1
vote
1answer
123 views

Calculate pressure equilibrium constant from concentration equilibrium constant

$$\ce{N2(g) + 3H2 (g) -> 2NH3(g)}$$ Calculate $K_\mathrm p$ from $K_\mathrm c$, given that $K_\mathrm c = \pu{4.2 M^-2}$ and that there is 0.2 moles of $\ce{N2}$, 0.6 moles of $\ce{H2}$ and 0....
0
votes
1answer
629 views

Solubility equilibrium [closed]

This is a worked example about solubility equilbrium I am new to this subject and I am really confused first of all I know that Q is the product of concentration of Ag and Cl in the solution and ksp ...
0
votes
1answer
875 views

Effect of temperature change in an equilibrium reaction

Talking about an exothermic reaction in equilibrium it is said that heat is on the product side, so according to Le Chatelier principle, the reaction should move backward to counteract the increase in ...
1
vote
2answers
155 views

Is the equilibrium constant in the expression based on pressure or concentration?

$$\Delta G^\circ=-RT\ln K$$ I have always assumed it to be $K_p$ because $\Delta G^\circ$ represents standard free energy change and the standard state for a gas is 1 bar. So I thought we must ...
1
vote
1answer
3k views

Why does reducing pressure cause the equilibrium to shift towards the side with less moles?

Take the example: $$\ce{N2(g) + 3H2(g) <-> 2NH3(g)}$$ I understand that if I increase the pressure of the system, it'll shift towards the $\ce{NH3}$ side. This is because of the reaction rate ...
2
votes
2answers
392 views

Is the application of Le Chatelier's principle wrong in this case?

In the reaction: $$\ce{N2(g) + 3H2(g) <=> 2NH3(g)}$$ Suppose the system has 3 moles of $\ce{N2}$, 1 mole of $\ce{H2}$ and 1 mole of $\ce{NH3}$ at equilibrium. $Q_\chi=K_\chi=8.33$ and $Q_p=K_p$. ...
3
votes
2answers
441 views

Le Chatelier’s principle when pressure of gases increased with the same stoichiometric coefficient

$$\ce{C (s) + H2O (g) <=> CO2 (g) + H2 (g)}$$ What will happen to the equilibrium when the pressure of gases is increased? What will happen to the yield of $\ce{H2}$? Since pressure ...
-1
votes
1answer
27 views

Influence of adding an acid to an equilibrium reaction that is not part of an equilibrium reaction [closed]

Question: The equation of chemical equilibrium reaction is the following: $$\ce{[Cu(OH2)4]^2+ + 4Cl- <=> [CuCl4]^2- + 4H2O}$$ The $\ce{[Cu(OH2)4]^2+}$ ions are of blue colour, while the $\...
3
votes
1answer
68 views

Two different methods to express the equilibrium constant give different results

$\pu{2.0M}$ of $\ce{I2}$ and $\pu{2.0M}$ of $\ce{Br2}$ are initially present in a reaction mixture. Calculate the equilibrium concentration of $[\ce{I2}]$ , $[\ce{Br2}]$ and $[\ce{IBr}]$ at $\pu{425K}$...
1
vote
0answers
57 views

Amount dry acid or sodium bisulphate needed for varying hardness values [closed]

My question is regarding the use of sodium bisulphate to lower the hardness of water. I am attempting to come up with a label to let consumers know how much product (dry acid or sodium bisulphate) is ...
0
votes
3answers
321 views

Pressure dependency in Haber Bosch ammonia synthesis

Haber-Bosch ammonia synthesis reaction: $$\ce{3H2 +N2 -> 2NH3}$$ According to the ideal gas law: $pV=nRT$ where constant volume implies $\displaystyle \frac nV=\frac p{RT}$ Then $\displaystyle ...
6
votes
2answers
3k views

Why is ortho-hydroxybenzoic acid more acidic than its para-isomer?

Why is ortho-hydroxybenzoic acid $(\mathrm{p}K_\mathrm{a} = 2.98)$ more acidic than its para-isomer $(\mathrm{p}K_\mathrm{a} = 4.58)$? March's Advanced Organic Chemistry (7th ed) gives the reason to ...
1
vote
1answer
991 views

What is the meaning of the term 'reserve acidity'?

In $\ce{CH3COOH/CH3COONa}$ buffer, the reserve acidity of the solution is due to the $\ce{CH3COO-}$ ions. What is the meaning of the term of 'reserve acidity' in the above statement?
1
vote
1answer
171 views

Voltaic cell and Nernst equation

It is given voltaic cell $\ce{Cu}|\ce{CuSO4}(\pu{10^-3 M})||\ce{CH3COONa}(10^{-2})|\ce{Pt}(\ce{H2})(\pu{1 atm})$. Find the potential at $\pu{50^\circ C}$. Given $K_\mathrm{a}$ for $H= 1.8 \times ...
0
votes
2answers
63 views

Is it right to compare the molarity of a substance with the probability of its molecules reacting?

I was watching this video on Khan Academy (about the equilibrium constant), and the analogy that they made really got me thinking. I wanted to verify whether it was completely correct, or just an ...
-1
votes
3answers
60 views

Clarifying understanding of shifting equilibrium in dynamic systems: [closed]

Firstly, let me confirm that my definition for right shift is correct: a right shift entails an increased ratio of product to reactant. Say you have the reaction A -> B. The standard notion is that ...
1
vote
1answer
31 views

Vapour-Liquid Equilibrium

I have been studying flash distillation, and I am reading the VLE tables my textbook has provided. I am looking at these tables and I am not understanding the data, I think. Why is the vapour mole ...