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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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0answers
18 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 ...
0
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0answers
44 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 ...
0
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0answers
40 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 ...
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1answer
20 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 ...
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0answers
33 views

Dissolved CO2 and buffer capacity of water: how quickly does it work? [closed]

Let's say we have a system that dissolves $\ce{CO2}$ in tap water. In my understanding, a small portion of dissolved aqueous $\ce{CO2}$ combines with water to form carbonic acid. Given some fixed ...
-1
votes
2answers
26 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 ...
0
votes
0answers
30 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 ...
1
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1answer
49 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 ...
0
votes
0answers
32 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
votes
0answers
63 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
51 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: $...
0
votes
1answer
37 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 ...
-1
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
56 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 -&...
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0answers
26 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 ...
0
votes
2answers
60 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
137 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 ...
-1
votes
1answer
23 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
34 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
73 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 ...
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0answers
47 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 ...
0
votes
1answer
47 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 ...
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0answers
27 views

What reactions will occur at the anodes and electodes of two iron electrolytic cells?

What reactions will occur at the anodes and electrodes of two iron electrolytic cells: both with iron metal electrodes, one with an iron(II) sulphate electrolyte, the other with an iron(III) sulphate ...
4
votes
1answer
151 views

Why do my equilibrium calculations on this HF/NH4OH buffer system not match those in literature?

I've been trying to reproduce Figure 2 from this research paper (full text available). The Problem However I can't seem to get the same values as in the paper. I did the math both by hand and with ...
0
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0answers
31 views

Total pressure conservation during equilibrium reaction

I tried to solve the following exercise but my solution is different from the one of the book and I can't understand why. The exercise is the following: With total pressure $$p_\text{tot}=\pu{0.5 ...
0
votes
1answer
23 views

Measure of partial pressure on blood

Here is the issue of blood gases partial pressure. On medical reports is common to see partial pressure of gas on blood, usually oxygen, but there is no gas in equilibrium with blood, so it is ...
6
votes
2answers
72 views

Why do most carboxylic acids have high pKa (~5) in spite of having a conjugate base ion that is stabilized by resonance?

This is from my textbook: Carboxylic acids owe their acidity ($\mathrm pK_\mathrm a$ of about $5$) to the resonance-stabilized carboxylate anions formed by deprotonation. Why are they such weak ...
1
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1answer
49 views

How to calculate the equilibrium constant of acetic acid-hydroxide ion equilibrium?

I am trying to calculate the equilibrium constant of the following equilibrium: $$\ce{CH3COOH (aq) + OH- (aq) <=> CH3COO- (aq) + H2O (l)}$$ I am aware that this reaction essentially goes to ...
2
votes
1answer
77 views

Why is the equilibrium constant of water with its vapour equivalent to its vapour pressure?

Can someone conceptually explain why the equilibrium constant is equivalent to the vapour pressure of water for the above equilibrium reaction? For example if $K = x$, then it is said that vapour ...
0
votes
0answers
16 views

How many components and phases are in an equilibrium system comprising lead sulfate, lead ions, and sulfate ions?

I am going to calculate the degrees of freedom ($F = C-P+2$) on the following system, but I can't figure out whether we have to take $\ce{PbSO4}$, $\ce{Pb^2+}$ and $\ce{SO4^2-}$ as a single component ...
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2answers
54 views

Why are temperature and pressure represented as the number 2 in Gibbs' Phase Rule?

In our class we are learning about Gibbs' Phase Rule; $F=C-P+2$, in which $F$ stands for degree of freedom, $C$ for number of components, and $P$ for number of phases in the system. Our professor told ...
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1answer
84 views

Calculating PH of solution after adding strong acid (equilibrium)

Consider the classic example when talking about acids and bases: Say you have 1M of $\ce{HCL}$ and you throw it into water, calculate the resulting pH (= concentration of $\ce{H3O+}$). The way this ...
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votes
1answer
24 views

Why does pH increase as a weak acid becomes more dissociated?

My Organic Chemistry (Wade, 9th ed) textbook mentioned the following note: "In most cases, the pKa of an acid corresponds to the pH where the acid is about half dissociated. At a lower (more acidic) ...
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votes
1answer
41 views

What mass of potassium lactate is needed to 300.0 mL of 0.238 M Lactic acid solution to make a solution with a pH of 4.00? pKa (lactic acid) =3.86

Upon attempt, I've yielded an answer of 11.91g. My calculations do not take 300 mL Lactic acid solution into account, and now I somewhat know the error is at least partially due to the fact that my ...
5
votes
1answer
67 views

What exactly is entropy? [closed]

I have looked at other questions, videos and articles but I kept reading disorganization, messiness or energy distribution (probability) or a thermodynamical equilibrium and stuff. What do we mean by ...
0
votes
1answer
68 views

Energy at constant Entropy and Volume

The system of constant entropy and constant volume will attain the equilibrium in a state of minimum energy. Why? I know that: $\Delta G= \Delta H-T\Delta S$ And at constant volume and entropy: $\...
1
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1answer
55 views

Equilibrium constant Kp for vaporization of water?

For the reaction H2O(l) -->H2O(g) it is given that Kp = p(H₂O(g))/p° where p° is the atmospheric pressure. Why is it not just equal to p(H₂O(g))?
2
votes
0answers
30 views

Reverse rate coefficient for thermolecular and thermal dissociation reactions

I am an astrophysicist working in exoplanetary atmosphere chemistry right now, in particular modelling the chemical kinetics taking place within the atmosphere. Based on this IOP article, we have that ...
1
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1answer
65 views

What is the effect of removal/addition of components of a reaction with unequal moles on both at constant volume by le Chatelier's principle?

This reaction is given in my book and the direction of shift of reaction on addition of $\ce{CO}$ and removal of $\ce{CO2}$ at constant volume is asked. $$\ce{2CO(g) + O2(g) ⇌ 2CO2(g) + \Delta H}$$ If ...
0
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0answers
9 views

What is the correct way of using the Law of Mass Action? [duplicate]

Because I thought of this example when reviewing solubility product, I'll use it: $$\ce{PbCl2->Pb^2+ + 2Cl-}$$ Let's say solubility (of $\ce{Pb^2+}$?) is $S$. Now, concentrations of $\ce{Pb^2+}$ ...
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0answers
26 views

Different values of concentration of product at equilibrium

$\pu{60g}$ of acetic acid and $\pu{46g}$ of ethyl alcohol are mixed with each other at a constant temperature and allowed to attain equilibrium. At equilibrium $\pu{58.2g}$ of ethylacetate and $\pu{...
2
votes
2answers
59 views

Are the best buffers those that are in a 1:1 ratio with its conjugate acid/base?

I wanted to comment this, but I don't have enough reputation, so I just made this a question. I know that buffers and their conjugate base/acid must exist in similar amounts for the buffer to be ...
0
votes
2answers
96 views

How do I find the theoretical pH of a buffer solution after HCl and NaOH were added, separately?

This question is about the theoretical pH of a buffer solution. Calculate the theoretical pH values expected for a $\pu{200mL}$ buffer solution containing a 1:1 ratio of acetic acid and sodium ...
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0answers
144 views

Calculating the pH of a solution of sodium carbonate

I've seen similar questions on this site, but I'm having trouble as my book said something else. For a $\pu{0.09989 M}$ solution of $\ce{Na2CO3}$, my book said: $$\ce{Na2CO3 + 2H2O -> H2CO3 + 2Na+ ...
1
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1answer
69 views

Approximated formula of acid dissociation constant

$K_\mathrm{a}$ can be expressed as $K_{\mathrm{a}} = \frac{[\ce{H^{+}}] [\ce{A^-}]} {[\ce{HA}]}$, however, it can be approximated that $K_{\mathrm{a}} = \frac{[\ce{H^{+}}]^{2}} {[\ce{HA}]}$. I ...
0
votes
1answer
102 views

Calculating base dissociation constant given the molarity and pH [closed]

At $\pu{25°C}$, a $\pu{0.100 M}$ aqueous solution of $\ce{C_6H_5NH_2}$ has $\mathrm{pH}=8.80$. Find the $K_{\mathrm{b}}$. I figured I would have to use an ICE table, but I am not too sure how to ...
0
votes
1answer
58 views

What is the citric acid concentration, [HCit], in the lemon juice?

The pH of lemon juice is about 2.1. What is the citric acid concentration, [HCit], in the lemon juice? I am given that $HCit \leftarrow \rightarrow H^+ + Cit^-$ and that $K_a = 8.4 \times 10^{-4}$. ...
1
vote
1answer
28 views

Does the way a reaction with gas moles shifts depend on Q or number of moles on either side of the reaction?

Given a container with the reaction $\ce{C2H4{(g)} + HCl{(g)} -> C2H5Cl{(g)}}$, if we inject $\ce{C2H5Cl{(g)}}$ to the container, what will happen? I thought of this in two different ways and got ...
1
vote
1answer
36 views

Increase in equilibrium concentration of the reactant via decrease in container volume

Consider the hypothetical reaction $\ce{3A(g) -> B(g) + C(g)}$; how to increase the equilibrium concentration of $\ce{A}$, given that the reaction is endothermic? increasing the volume of ...
2
votes
0answers
46 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 ...