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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Kc(equilibrium constant) and Kp

Its given in the book that at 12.18kelvin Kc=Kp. How is that equated from the equation Kp= Kc(RT)^∆ng. I am unable to sort it out, please guide me in to the topic....
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Which is a stronger acid: H3O+ or HCl?

I know as a fact that HCl is a stronger acid than H3O+, but I want to know the reason behind it. The definition of an acid is a substance which dissociates to give H3O+ ions. In that case H3O+ should ...
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Derivation of formula for Hydrolysis constant

While studying acid-base equilibrium I thought I would derive the formula for hydrolysis constant myself. But I ended up getting a weird result and I am not able to understand where I went wrong. ...
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3 component (ternary) system in equilibrium

If the components of a system were Cl2, Br2, and I2, how could I describe this system under equilibrium conditions when the number of phases is at a maximum? If there are 3 components, using the ...
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Components of a system in equilibrium

If the components of a system were $\ce{Cl2}$, $\ce{Br2}$, and $\ce{I2}$, how could I describe this system under equilibrium conditions when the number of phases is at a maximum? If there are 3 ...
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Why mole fraction equilibrium constant depend on pressure and volume?

The ratio of rate constants for forward and backward reaction gives us the equilibrium constant (say kc). 1.Rate constants depend on temperature and catalyst (Kinetics). 2.Their ratio i.e ...
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How to determine the theoretical carbonic acid concentration in soda water from a Soda Stream

I've seen it cited that commercial carbonation devices like a SodaStream put about 100 psi (700 kPa) of pressure to dissolve gaseous $\text{C}\text{O}_{2}$ in to solution. I've also heard that the ...
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Problems regarding Kc,Kp and rate of reaction

In our chemistry textbook, the equilibrium constant $K_c$ is derived this way: $$\ce{aA + bB <=> cC + dD}$$ in this reaction, rate of forward reaction is $k_f= k_1[A]^a[B]^b$ rate of backward ...
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Why are aqueous solutions included in the equillibrium constant but liquids are not? [duplicate]

I understand solids are insoluble and will just sit at the bottom of the vessel so we don't include them. But I am confused as to why aqueous solutions are used in the equilibrium equation but ...
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What guarantees that there is a thermodynamic equilibrium in a closed chemical reaction network independently of the mass-action kinetics? [closed]

I would like to know according to which we can state that there is a unique equilibrium of a closed chemical reaction network (at constant circumstances) without supposing mass-action kinetics if time ...
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Addition of solid to reaction at equilibrium [duplicate]

In the reaction: $$\ce{CaCO3 <=> CO2 + CaO}$$ when there is an addition of $\ce{CaCO3}$ (reactant) normally one one would expect that by increasing the reactants the rate of forward reaction ...
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Finding the mole fraction

At $25\ \mathrm{^\circ C}$ the vapor in equilibrium with a solution containing carbon disulfide and acetonitrile has a total pressure of $263\ \mathrm{torr}$ and is $85.5\ \mathrm{mol}\text{-}\%$ ...
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Effect of an inert gas on steam vapor pressure at equilibrium

Suppose we have a closed container with mobile walls, so it will change its volume in order to equal the external pressure(constant) to the internal pressure. This container has inside it a liquid ...
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Vapour Pressure and Equilibrium

A liquid in its equilibrium with its vapour is in a sealed container at a fixed temperature. The volume of the container in suddenly increased. a) What are the changes in the rate of evaporation and ...
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Finding OH- concentration given the H+ concentration - diverse methods

There was this exercise which asked to find the OH- concentration given the H+ concentration, i firstly calculated the pH as -log[H+], did 14-pH to find the pOH and then did 10^(-pOH) to find the ...
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Can equilibrium be reached in a non-reversible chemical reaction?

Can chemical equilibrium only be achieved in a reversible process? I have only seen equilibrium in processes that are reversible so I was wondering if it were possible in reactions that are not ...
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Equilibrium Question from USNCO local exam 2016

IBr(g) is in equilibrium with I2(g) and Br2(g) at 150 ºC: 2 IBr(g)<-----> I2(g) + Br2(g) K = 8.50*10^-3 Initially, a closed vessel at 150 ºC has a partial pressure of IBr of 0.350 atm and ...
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Ignoring the difference of concentrations of reactants. Equilibrium

Recently at school, while studying equilibrium we learned that in problems where the initial concentrations of reactants and the equilibrium constant are given, there is a special formula to determine ...
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What will be the effect on the solubility of $0.1\ \mathrm{mol}$ of $\ce{CH3COOAg}$ in presence of $1\ \mathrm{l}$ of $0.1~\mathrm{M}\ \ce{HNO3}$ solution? $$K_\mathrm{sp} (\ce{CH3COOAg}) = 10^{-... 1answer 69 views Calculate the pH of Na2CO3 Given information: K_\mathrm{a}(\ce{H2CO3}) = 4.3 \times 10^{-7}, K_\mathrm{a}(\ce{HCO3-}) = 4.8 \times 10^{-11}, {{\ce{[Na2CO3]}=0.20\ \mathrm{M}}} This was a question in an exam and I'm ... 1answer 32 views Equilibrium Constant Explained I'm not interested in a simple telling of what the properties of the equilibrium constant are and how to use them. I'm more hoping for an explanation of where it came from/how it might be possible to ... 1answer 26 views Calculating Ratio of Stability Constants Solution I contains a mixture of \ce{FeCl2} and \ce{FeCl3}, and solution II contains a mixture of \ce{K4Fe(CN)6} and \ce{K3Fe(CN)6}. The concentrations of iron-containing species satisfy the ... 0answers 67 views Decomposition of CaCO3 in a sealed vessel For the equilibrium$$\ce{CaCO3(s) <=> CaO(s) + CO2(g)}$$\Delta H^\ominus = 178\ \mathrm{kJ\ mol^{-1}} and \Delta S^\ominus = 160\ \mathrm{J\ mol^{-1}}. I'm asked to suppose that 1\ \... 1answer 85 views Difference between freezing point and melting point I do not understand why for mixtures freezing point is lower than melting point. Are not the two representing the same equilibrium between solid and liquid which we are approaching from two different ... 2answers 185 views Why is EDTA most soluble at a pH 8? (addition of NaOH) Although Wikipedia says that EDTA is a very soluble salt, preparing a solution (.5M) is a pain in the neck. It takes a lot of time and still doesn't dissolve. Although addition of a few drops of NaOH ... 0answers 32 views Chemical equilibrium and Le Chatelier Braun for ammonia production In the book of Chemical, biochemical and engineering thermodynamics 4th edition from Stanley I. Sandler (Wiley, 2006), there is a problem about the ammonia producing reaction at page 770. 13.17 The ... 0answers 29 views Chemical Equilibrium - Diluting a system by adding water Adding water to an aqueous system, the system becomes diluted and responds by favoring the reaction with the most amount of ions in solution. But apparently, adding 3\ \mathrm{mL} of water to \ce{... 2answers 55 views Phenolphthalein as a indicator for the titration of benzoic acid Question: Justify the use of phenolphthalein (\mathrm{p}K_\ce{in}=9.4) as a indicator for the titration of benzoic acid (K_\mathrm{a}=6.3\times 10^{-5}) with \ce{NaOH}. My attempt: I can ... 0answers 27 views Why does changing the dilution of an aqueous equilibrium shift the equilibrium? Say we have the equilibrium$$\ce{A_{(aq)} + 2B_{(aq)} <=> C_{(aq)} + D_{(aq)}}$$meaning the formula for the equilibrium constant is$$\ce{K_{c} = \frac{[C][D]}{[A][B]^2}}$$My understanding is ... 1answer 32 views Why is the water dissociation constant valid for acid/base solutions? The water dissociation constant was first defined with respect to dissociation of water into hydroxyl and hydronium ions. How then can one say that it is valid for an acidic solution, that is, even in ... 2answers 278 views What does curly brackets {} mean? I learned that square brackets ex: [H_2O] can be used to denote the concentration of water molecules in a fluid. The notation used much in equilibrium problems and such. However, sometimes I have ... 1answer 29 views Acid - Base Equilibrium Suppose we had a closed system proceeding according to,$$\ce A +2\ce B \rightleftharpoons 2 \ce C$$And that three experiments produced the following concentration data. Experiment 1: \begin{... 1answer 56 views What is the use/importance of the equilibrium constant Kc [closed] I understand what the equilibrium constant is, however when reading in my textbook it has occurred to me that I do not understand what it's actual use/importance is. One specification in my syllabus ... 2answers 98 views What is the difference between the equilibrium position and the equilibrium constant? I used to think that the equilibrium constant was a quantitative measure of the equilibrium. However, changing concentration and pressure in a system at equilibrium that shifts the equilibrium doesn't ... 1answer 45 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 ... 0answers 20 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, ... 0answers 40 views NaCl Electrolysis - Dilute vs Concentrated - Nernst Equilibrium Interested to know if there is a critical concentration at which \ce{Cl-} will oxidise over \ce{H2O} and if this can be determined using the Nernst equation. That is, obviously if [\ce{Cl-}]>... 1answer 42 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 ... 0answers 27 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 \... 0answers 26 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 ... 0answers 36 views Measuring the Kc of equilibrium between NO2 and N2O4 [closed] 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 ...
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: $K_p=e^{\frac{-\Delta G^0}{RT}}$ ...
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 mixture ...