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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7 views

What is the spontaneity of reaction when we add KCl to water? [on hold]

Is it spontaneous? Does the Gibbs free energy decrease after the reaction takes place?
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1answer
25 views

Temperature in the Gibbs Free Energy equation

My professor gave us 2 different ways to calculate this problem. I did it using the Clausis-Clapeyron equation. However, I don't quite get the second method because I thought that if the change in ...
0
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0answers
19 views

how calculate thermodynamic properties using a given chart of phase equilibrium

the following chart is given and the properties below the table is desired (in 313.15K), The Table is for H2S(1) in a ionic solvent(2),and also the Henry constant must be calculated at that ...
0
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12 views

Does reaction quotient Q take into account pure solids and liquids?

I understand that the equilibrium constant does not take into account the concentrations/ pressures of pure solids and liquids. How about the reaction quotient? In the following reversible reaction, ...
1
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0answers
28 views

NaCl Electrolysis - Dilute vs Concentrated - Nernst Equilibrium

Interested to know if there is a critical concentration at which $\textrm{Cl}^{-}$ will oxidise over H$_2$O and if this can be determined using the Nernst equation. That is, obviously if ...
0
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1answer
28 views

shifting of equilibrium

Does it mean that if one side of a reaction is favoured, the reaction will shift to the other side? As I was reading up on the van't Hoff equation, it says that an increase in temperature of an ...
1
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0answers
21 views

Does the activity product decrease with increasing ionic strength?

I have a question regarding what happens to the solubility of $\ce{CaSO_4}$ or the rate that $\ce{CaSO_4}$ will dissolve when we add $\ce{NaCl}$ to the solution: $\ce{CaSO_4}$ will dissolve into ...
1
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0answers
25 views

Equilibrium constant in a reaction with stoichiometric coefficient 1/2

I have a doubt. I calculated the equilibrium constant for the follow reaction at 298 K $CH_4(g) + 1/2 S_8 (s) \leftrightarrow CS_2 (l) + 2 H_2S(g)$ I reached to $1.65 \times 10^{-9}$. However my ...
2
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0answers
25 views

Measuring the Kc of equilibrium between NO2 and N2O4

I'm trying to measure the $K_c$ of the equilibrium reaction $$\ce{2 NO2 (g) <=> N2O4 (g)}$$ in different temperatures. How would I do this do this in a normal school laboratory? I was thinking ...
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0answers
20 views

How to evaluate standard enthalpy, standard entropy and standard free energy in a temperature different that 298K

A question is asking me to calculate the equilibrium constant of a given reaction of gases at 373 K. My immediate thought was to think about van't Hoff equation: $K_p=e^{\frac{-\Delta G^0}{RT}}$ ...
1
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1answer
36 views

Percent composition by volume of the reaction H2 + Br2 <=> 2HBr

For the reaction $\ce{H2(g) + Br2(g) <=> 2HBr(g)}$ at a certain temperature, $K=1$. Determine the composition (in per cent by volume) of the equilibrium reaction mixture if the initial ...
3
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2answers
89 views

Combining acid dissociation constants to determine pH of diprotic acid

If I have a diprotic acid with $K_{\mathrm{a1}}$ and $K_{\mathrm{a2}}$ as the acid dissociation constants, why can't I calculate the final $\mathrm{pH}$ using $K = K_{\mathrm{a1}}\cdot ...
0
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1answer
18 views

How can you change the proportions of reactants and products at equilibrium if Le Chatelier's principle is occurring?

For example, how could you make a buffer with equal concentrations of acid and conjugate base? If you add more conjugate base, it will shift the equilibrium to form more acid, which will keep the ...
-1
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1answer
38 views

Why don't we take into account the auto-protonation of water when measuring its concentration?

When we calculate the concentration of water at $ 25~^\circ\rm C $, why don't we assume dissociation of water at this temperature? $$\ce{H2O <=> H+ + OH-}$$
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1answer
83 views

Why do acids mix in water faster than bases?

I have $100\ \mathrm{L}$ of water in a tank with an mixer inside and want to know how fast the tank mixes at a given rpm-setting. I am adding $50\ \mathrm{mL}$ of $2\ \mathrm{N}\ \ce{HCl}$ and see ...
10
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2answers
262 views

How is volatility useful in the production of acids?

Sulfuric acid because of its low volatility can be used to manufacture more volatile acids from their corresponding salts. How does volatility affect the production of acids? Isn't it that ...
1
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2answers
41 views

What's the Kp value?

A mixture of $1\ \mathrm{g}$ of $\ce{H2(g)}$ and $1.06\ \mathrm{g}$ $\ce{H2S(g)}$ in a $0.5\ \mathrm{L}$ flask come to equilibrium at $1670\ \mathrm{K}$. At equilibrium, there are $8\times10^{-6}\ ...
0
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0answers
37 views

pH of a double buffer

If $1,2,3,4$ moles of $\ce{H3PO4}$,$\ce{NaH2PO4}$,$\ce{Na2HPO4}$ and $\ce{Na3PO4}$ respectively are mixed together to form an aqueous solution of $1$Litre , resulting $\ce{pH}$ is? This question has ...
3
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0answers
43 views

The behaviour of Ag3PO4 in solution

To a 1L flask, we add $4.1900\mathrm{g}$ ($0.01001\ \mathrm{moles}$) of $\ce{Ag3PO4}$, then fill it up with water. Knowing the following constants, we are asked to find the concentration of all ...
1
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1answer
104 views

Relationship between pKa and pKb

The $\mathrm{p}K_\mathrm{a}$ of $\ce{NH3}$ is $38$. Does it stand for the following equilibrium: $$\ce{NH4+ <=> NH3 + H+} \tag{1}$$ With $K_\mathrm{a} = 10^{-38}$ for reaction $(1)$, indicating ...
3
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2answers
224 views

Is it possible for one of reactants to deplete before achieving equilibrium

Consider the following reaction where $\ce{A}$ & $\ce{B}$ reacts to produce $\ce{C}$ & $\ce{D}$. $$\ce{ A(g) + B(g) <=> C(g) + D(g)}$$ Is it possible for $\ce{A}$ or/and $\ce{B}$ to ...
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0answers
29 views

Equilibrium Problem Involving Solids: Faulty?

I am convinced that this is a faulty problem: $\ce{2 Cu + S -> Cu2S}$ For the reaction above, $\Delta H$, $\Delta S$, and $\Delta G$ are all negative. Which of the substances would ...
4
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2answers
35 views

Why is iron(II) fluoride thermodynamically favorable when dissolved in acid?

I am reviewing for the AP Chemistry test, and the question is this $$ \ce{FeF2(s) <=> Fe^2+(aq) + 2F^- (aq) } \quad K_1 = 2\times 10^{-6} $$ $$ \ce{F- (aq) + H+ (aq) <=> HF(aq)} \quad ...
3
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47 views

Apparent solubility of Ag2C2O4 in a buffer solution

We take the following quantities and mix them together: $20\mathrm{mL}$ solution of $\ce{AgNO3}$ $0.001 \frac{\mathrm{moles}}{\mathrm{dm^3}}$ $20\mathrm{mL}$ solution of $\ce{H2C2O4}$ ...
2
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25 views

Spontaneous and Favoured Chemical Reactions

I have some problems in understanding what is the difference between a reaction which is spontaneous and a reaction which is termodynamically favoured. I'm looking at the equation of Gibbs Free ...
3
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1answer
57 views

The effect of reactant concentration on when equilibrium is established

Take the equation $$\ce{A(g) <=> B(g)}$$ where the reaction is first order with respect to A. The rate law is thus $$\frac{\mathrm d[\ce{A}]}{\mathrm dt}=-k[\ce{A}]$$ Say you run the reaction, ...
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58 views

How to find deltaG when given the equilibrium constant and temperature?

For the reaction, $$\ce{N2O4(g) <=> 2NO2(g)}$$ the equilibrium constant in terms of concentration, $K_c$, at $100~^\circ\rm C$ is $0.36$. What is ${\rm\Delta} G$? I used the equation ...
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1answer
30 views

A doubt in chemical equilbrium

say we have a reaction N2O4 reversible 2NO2 for this reaction,if initial number of moles of N2O4 is 'a' can we write t = 0 a - at equilbrium a-x 2x similarly can we do the same for pressure? i.e. ...
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45 views

A problem in ionic equilbrium

Question 1998(b) My attempt: I thought that $\ce{AgCl}$ would yield $\ce{Ag+}$ and $\ce{Cl-}$ ions, whose concentration can be found from $K_{sp}$ as $\sqrt{K_{sp}}$. This $\ce{Ag+}$ reacts with ...
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1answer
15 views

Acid-Base Equilibrium Concept question

I have a question about when to use H3O+ and when to use the actual compound. I'm not really sure how to word this question so I'll show you an example of what I mean. Example of using H3O: "A ...
3
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1answer
55 views

Understanding effect of ph on solubility of salt

In the following picture why Ksp is not simply S2- ? Why is f included with one species only? Please explain the last part. What does f represent and why it is used in molar solubility?
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1answer
25 views

Concentration and volumes

In the reaction: $$\ce{H2SO4 +CaCO3 \to CO2 + H2O + CaSO4}$$ Does altering the concentration of the sulfuric acid change the volume of the carbon dioxide produced [the volume of the sulfuric acid is ...
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19 views

Total Pressure in equilibrium

I got a very confusing question. I need to calculate the total pressure in a reactor. The gases are Hydrogen and Nitrogen in a 3:1 ratio that reacts to Ammonia. All the final mole fraction of those ...
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1answer
80 views

Determine if an acid base reaction will occur

I'm wondering why some acid base reactions occur, let's say for example: $$\ce{CH3CH2OH + H2O <<=> CH3CH2O- + H3O+}$$ Why does this reaction occur, because the alkoxide ion is a really ...
2
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2answers
41 views

Change in equilibrium when not all product and reactant are increased

$$\ce{2NOCl <=> 2NO + Cl2}$$ What will be the effect on equilibrium concentration of $\ce{NOCl}$ when equal moles of $\ce{NOCl}$ and $\ce{NO}$ are introduced in the mixture at constant ...
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15 views

Raoult's Law and Equilibrium

Vapor pressure is numerically the equilibrium constant of a liquid-vapor equilibrium. And when there's a simultaneous equilibrium of two separate reactions both the equilibria need to be satisfied ...
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1answer
30 views

Why do we not include water in equilibrium expression calculations? [duplicate]

Why do we not include water in equilibrium expression calculations? And can you go into detail on why pure liquids and solids have a constant concentration as well, please and Thanks.
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1answer
45 views

Why does a buffer work best at the pH closest to its pKa?

I think I'm having trouble understanding exactly how the pKa relates here on a conceptual level. For example I know that carbonic acid works somewhat well as a buffer at pH near 7, since its pKa is ...
0
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1answer
23 views

Determining the temperature at which 90% of the reactants in a equilibrium have reacted

I have the following problem I am stuck on, specifically the last bit (iii). The first parts are fairly trivial and I have arrived at the following equation to determine the temperature: ...
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0answers
11 views

Physical chemistry and pH [duplicate]

My question may be strange a little but how could dilution change the pH, For example:if we have an acid solution and we add water the pH increases, but if the water has equal concentrations of H+ and ...
1
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0answers
27 views

Dimerisation effect on distribution ratio?

The question reads: "Carboxylic acids (RCOOH) form dimers in solvents of low polarity such as benzene and carbon tetrachloride. Using suitable equations, explain the effect of association on the ...
1
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1answer
50 views

Unique Solubility Expression for Sulfide Salts

While looking at aqeuous $\ce{K_{sp}}$ values in the back of my textbook, I noticed that there is a asterisk by all of the sulfide compounds (such as $\ce{HgS}$), and the asterisk says, "For a ...
1
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1answer
21 views

Mixing a Tagged Sample of Lead Iodide with another Iodide Salt [closed]

A sample of sparingly soluble $\ce{PbI_2{(s)}}$ containing radioactive $\ce{^{133}I}$ is added to 0.10 M $\ce{KI_{(aq)}}$ and stirred overnight, what happens? I The radioactivity of the liquid phase ...
2
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16 views

Calculate the flow rate in the steady state of a dynamic equilibrium

I have the following situation: I am interested of the reactions rate of an enzymatic reaction, depending of the substrate concentration. The thing is, that I don't add the substrate directly to the ...
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0answers
15 views

How to calculate the gas pressure of HCl over a saturated CuCl2 solution

I have a concentrated solution of $\ce{CuCl2}$ ($<200~\mathrm{ml}$, surface area $2100~\mathrm{cm^2}$). I saw a note about protecting metal equipment from $\ce{HCl}$ attack in the room ...
3
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1answer
132 views

How is the association/ dissociation constant derived?

I came across the following formula to find the association of a solute in particular solvent. Suppose the concentration of the solute given in water (or in some other solvent in which it does not ...
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0answers
16 views

Halving the electrolyte concentrations of a voltaic cell

Say you have a standard voltaic cell with $Q=1$. The concentrations of both the electrolytes are at 1.0 M. If you halve the concentrations in both to 0.5 M, $Q$ still equals 1 and ...
0
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1answer
23 views

The equilibrium constant of a reaction only involving pure solid or liquid

How to calculate the equilibrium constant of a reaction only involving pure solid or liquid. For example reaction $$\ce{S(s) + Hg(l) -> HgS(s)}$$ or $$\ce{S(s) + Mg(s) -> MgS(s)}$$
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47 views

Finding Ka given H+ value and molarity

Can someone solve this problem? I just need to confirm my solution A $\rm1.0~M$ solution of acid has $$\ce{[H+]} = \rm 1\times10^{-2}~M$$ Find the value of Ka. My solution is: $$\ce{[H] = ...
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30 views

Do solids affect equlibrium?

After doing a calculation on $K_{C}$, I was told that solids do not affect the calculation. This is confusing me. Is there a specific reason why solids do not affect the equilibrium shift? Thanks.