What is Equilibrium constant: Definition and 97 Discussions
The equilibrium constant of a chemical reaction is the value of its reaction quotient at chemical equilibrium, a state approached by a dynamic chemical system after sufficient time has elapsed at which its composition has no measurable tendency towards further change. For a given set of reaction conditions, the equilibrium constant is independent of the initial analytical concentrations of the reactant and product species in the mixture. Thus, given the initial composition of a system, known equilibrium constant values can be used to determine the composition of the system at equilibrium. However, reaction parameters like temperature, solvent, and ionic strength may all influence the value of the equilibrium constant.
A knowledge of equilibrium constants is essential for the understanding of many chemical systems, as well as biochemical processes such as oxygen transport by hemoglobin in blood and acid–base homeostasis in the human body.
Stability constants, formation constants, binding constants, association constants and dissociation constants are all types of equilibrium constants.
Homework Statement
Evaluate the equilibrium constant for the formation of triodide ion.
I2 + I- ------> I3-
a 298K, if EI2|I-o = 0.6197V and EI3-|I-o=0.5355V
I don't understand one thing - At equilibrium, ΔG=0 so that Eocell=0 (from the equation ΔG=-nfE) but Eocell is not zero for...
Why is that the Kf (thermodynamic equilibrium constant) exact and not dependent on temperature meanwhile Kp (apparent equilibrium constant) is dependent on temperature.
They are essentially the same formula except for an activity coefficient which doesn't change in response to temperature...
Haha --- nvm, found it. Sorry/Thanks... ^_^
Where does the 2.19 come from?
How many moles of NaOH would need to be added to 500.0 mL of 0.70 M HClO to create a buffer with a pH of 7.80?
Initially, we have 0.35 mol of HClO. We are going to add NaOH which will react with the weak acid to...
Hey all
I have trouble understanding something about the Equilibrium constant.
If you have this chemical equilibrium:
pA + qB \Leftrightarrow rC + sD
You can define the equilibrium constant with
[C]r [D]s
______ = K
[A]p [B]q
I don't understand why you multiply the concentrations...
Finding the Equilibrium Constant (K)I have been having a bit of trouble with this question, if anyone could guide me on where I am going wrong it would be greatly appreciated!
"Reaction 1: N2 + 3H2 = 2NH3
Write down an expression for the equilibrium constant K, for reaction 1.
At 25 degrees...
Hello, geniuses! :)
I am having a problem in chemistry...
What is this systems equilibrium constant expression? And under what conditions (temperature, pressure, concentrations) you can most fully get rid of SO2?
I really have no idea with what to start... :/
Homework Statement
0.15 mole of CO is taken in a 2.5L flask is maintained at 705K along with a catalyst so that the folwing reaction takes place
CO + 2H2 ---> CH3OH(g)
Hydrogen is introduced till the total pressure of the system is 8.5atm at equilibrium and 0.08 mole of methanol is...
What is the equilibrium constant of the reaction?
NO_{3}^{-} + NADH + H^{+} <=> NO_{2}^{-} + NAD+ + H_{2}O
I wrote in an exam that the [NADH] and [H2O] remain constant in the reaction.
So my answer is
K = \frac {[NO_{2}^{-}] [NAD^{+}]} {[NO_{3}^{-}] [H^{+}]}
which is wrong.
The...
Determine the equilibrium constant, my working is below:
Equilibrium reaction:
http://img34.imageshack.us/img34/5106/reactiondy.jpg
At 730 oC the equilibrium concentrations of reactants and products are:
[H2 (g) ] / mol dm-3 : 2.40 x 10-7
[Cl2 (g)] / mol dm-3 : 2.40 x 10-7
[HCl...
Hello!
Here is an equation that i sometimes use in calculating enthalpy of reaction aA+bB=cC+dD.
a,b,c and d are stoechiometric coefficients, A,B,C and D are chemical compounds in reaction. They say that is an other form of the third law of thermodynamic, can one guide me please to derive it...
Homework Statement
Calculate the value of the equilibrium constant at 25 degrees celsius for the following reaction:
5Fe2+ + MnO4- + 8H+ ----) 5Fe3+ + Mn2+ + 4H2O
Homework Equations
The equation above is the product of these redox reactions:
1) MnO4- + 8H+ + 5e- ----) Mn2+ + 4H2O E=...
why the equilibrium constant only depending on temperature but not concentration and partial pressure ?
Since K= [product]/[reactants], why the value of K remain the same as [product]or [reactant] increase ?
Homework Statement
Calculate the equilibrium constant for the reaction
H2(g) + I2(g) <---> 2HI(g)
at 80oC. The vapor pressure of solid iodine is 0.0216 bar at that temperature. If 52.7g of solid iodine are placed in a 10.0 L vessel at 80.0oC, what is the minimum amount of hydrogen gas that...
The relation, ΔG = -RT ln(Keq)
is ubiquitous.
It says that for a reaction, the change in Gibbs energy is proportional to the logarithm of the equilibrium constant.
But where does this come from?
I've been reading through many books and haven't yet find any that derive or indicate the...
Homework Statement
OK. so i have a separation science lab report write up to do which involves the equilibrium of the tri-iodide ion dissociating into iodine and iodide. I know the concentrations at room temperature (which is very cold, about 10 degrees C, where i come from!), and thus the...
Homework Statement
2NS(g) + 2H2(g)<---> N2(g) + 2H2S(g) @ equilibrium in a 4.L flask @ 25o
C. 2.5 mol of eah component initially is put into the flask. At equilibrium, 2.5 mol of NS is present. what is Kc for the rxn at this temp??
Homework Equations
Kc=[products]/[reactants]
M=moles/L...
Homework Statement
For the equilibrium PCl5 <---> PCl3 + Cl2, all gases, Keq = 4.16e-2. The equilibrium concentration of PCl5 is 1.0 M, and both PCl3 and Cl2 are 0.204 M. If the volume of this closed system is doubled, what are the concentrations of each gas when a new equilibrium is reached...
Homework Statement
Consider the system
CO2(g) + H2(g) <====> CO(g) + H2O(g)
Initially, 0.25 mol of water vapour and 0.2 mol of carbon monoxide are placed in a 1.00 L reaction vessel. At equilibrium, spectroscopic evidence shows that 0.1 mol of carbon dioxide is present. Calculate K for...
Homework Statement
Find the eq. constant for the reaction
CH3COOH (aq) + NO2- (aq) = CH3COO- (aq) + HNO2 (aq)
The Attempt at a Solution
I find Ka for the reaction CH3COOH = CH3COO- + H+ and Kb for the reaction NO2- + H+ = HNO2
But what are the rules then? I try multiplying the...
Please help me the following questions
In an experiment to determine Kc , the equilibrium constant for the reversible reaction
2HI<==> H2 + I2
0.21 g of hydrogen iodide was heated at 530℃ in a bulb of volume 100 cm^3 until equilibrium was reached . This bulb was broken under potassium...
I did an experiment in my Chem II class that required finding the equilibrium constant for this reaction
Fe3+ + SCN- ->Fe(SCN)2+
For the experiment, I had to use a calibration curve and Beer's law. How do I know that the calibration curve obeys Beer's law? I know that it would have to be a...
Homework Statement
The total pressure of gases in equilibrium with solid sodium hydrogen carbonate at 110.0 degrees C is 1.648 atm, corresponding to the reaction
2NaHCO3(s) <--> Na2CO3(s) + H2O(g) + CO2(g)
a) Calculate the value of the equilibrium constant at 110.0 degrees C.
The...
Homework Statement
The following reaction is at equilibrium at one atmosphere, in a closed container
NaOH(s) + CO2(g)-> NaHCO3 (s)
which, if any, of the following actions will decrease the total amount of CO2 gas present at equilibrium?
1)decreasing the volume of the container
2) none...
Homework Statement
Consider an ideal-gas mixture of atoma A, atoms B and molecules AB, undergoing the reaction AB <---> A+B. If n_A, n_B, and n_{AB} denote their respective concentrations, then show that, in equilibrium
\frac{n_{AB}}{n_A n_B} = V \frac{f_{AB}}{f_A f_B} = K(T)
(the law...
At 350degress celcius the equilibrium constant is 70. at equlilibrium the concentration if HI is 1.32 mol/L and that of H2 is 0.100 mol/L.
what is the concentration of I2?
would it be 0.32?
One thing that always bothered me in Chemistry is how the equilibrium constant is written. It never made sense to me.
If I take a simple bimolecular reaction approaching equilibrium :
aA + bB \mathop{\rightleftharpoons}^{k_1}_{k_{-1}} cC + dD
From ART ,
r_1 = k_1 [A]^ \alpha...
Homework Statement
Not really a textbook question, but I've read from numerous sources that changing the concentration of the reactants/products won't change the equilibrium constant. Why isn't this contradictory?
Assume the reaction:
xX + yY <---> zZ
where x,y,z are the coefficients of...
Homework Statement
Given the equilibrium,
A2(g) + 4C(g) 2AC2(g), K1 = 4.8
It follows that, for the reaction,
AC2(g) A2(g) + 2C(g), K2 = X
X would be
Homework Equations
The Attempt at a Solution
Since the equation is the inverse, i know to use 1/K1.
The mole ratio of...
Homework Statement
Using information from tables, calculate the equilibrium constant K of the following reaction at 32 degrees C.
PCl_5 \rightarrow PCl_3 + Cl_2
\Delta H^0_{rxn} = 68.6kJ
a) 4.62 \times 10^{-3}atm
b) 216 atm
c) 7.81 \times 10^{-11}atm
d) 163 atm
Homework Equations
\Delta...
Hi, I'm completely out of ideas for this problem, and any help would be really appreciated.
Homework Statement
At 850 degrees C and 1 atm pressure, a gaseous mixture of carbon monoxide and carbon dioxide in equilibrium with solid carbon is 90.55% CO by mass. Find the equilibrium constant...
Why is the equilibrium constant, k defined the way it is?
There are other expressions that would also be constant at the chemical equilibrium. These expressions could contain terms that are concentrations of the chemicals at eqiulibrium which will always be constants. So multiply a bunch of...
The relationship between free energy and the equilibrium constant is
Go = -RT ln K
By measuring the pH at various temperatures, the Kb for NH3(aq) was found to be temperature dependent, yielding the following values:
temperature (K) Kb
283 1.34 X 10-5
293 1.42 X 10-5
303 1.50 X...
The value of Keq for the reaction: 2H2S(g) <-> 2H2(g) + S2(g) is 4.20x10^-6 at 830 degrees celsius.
a) What is favoured in this reaction, reactants or products?
b) What concentration of S2 can be expected at equilibrium after 0.200 mol of H2S is injected into an empty 1.00 L flask?
why does the equilibrium constant vary only with temperature?
and why is pure substances like solids and liquids not count toward the equilibirum equation?
why do you have to have a reference pressure of 1 atm? (i know this is to take away the units but does this hav a logical function...
Therhelp ! modynamics and the equilibrium constant
Thermodynamics and the equilibrium constant
Okay I have a question about the equation (* means change) (*() means stander condition) so [G=*(G)+RT ln (Keq)] or just equation *(G)= - RT ln(Keq)
So what dose the (Keq) stander for? Kc...
Calculate Ksp for PbI2 at 25 C based on the following data:
SPECIES------------deltaG_f kJ/mol
Pb (2+) (aq) -------(-)24.4
I- (aq)-------------(-)51.6
PbI2 (s)------------(-) 173.6
a. 4 x 10-31
b. 8 x 10-18
c. 9 x 10-9
d. 5 x 10-5
PbI2 <-> Pb (2+) + 2I-
Use...
1) Sulfuryl chloride, SO2Cl2, is a highly reactive gaseous compound. When heated, it decomposes as follows.
SO2Cl2(g) <===> SO2(g) + Cl2(g)
This decomposition is endothermic. A sample of 3.509 grams of SO2Cl2 is placed in an evacuated 1.00-liter bulb and the temperature is raised to 375 K...
I feel like I know what I'm doing but I'm not getting an answer that is offered. Heres the question:
Dinitrogentetraoxide partially decomposes according to the following equilibrium:
N2O4 (g) ---> 2NO2 (g) (an arrow going other way too)
A 1.00-L flask is charged with .400 mol...
I am having serious difficulty understanding the concept of the equilibrium constant in a reversible chemical reaction. Maybe one of you all can help?
Suppose we have the following reversible chemical reaction:
1) aA + bB <---> cC + dD
The equilibrium constant for the reaction is said...
N2(g) + 2O(g) <--> 2NO2(g)
At a certain temperature, the follwoing are the equilibrium concentrations for the above reaction:
[N2] = 8.0 mol/L
[O2] = 2.0 mol/L
[NO2] = 4.0 mol/L
Determine the equilibrium constant.
My answer..
Ke = [NO2]^2 / [N2][O2]^2
Ke = [4.0]^2 /...
Could someone please help me with this problem?
Samples of A (2.5 mol) and B (1.0 mol) are placed in a 5.0L container and the following reaction takes place:
2A(g) <--> B(g) + C(g)
At equilibrium, the concentration of A is 0.20M. What is the value of...
DG = -RTln(K) always valid?
Hi,
For a reaction at equilibrium, A<==>B, then the free energy can be defined as
DG = -RTln(K), where K = [B]/[A].
This is fine for an isolated equilibrium. But suppose that the system is not isolated so that A<==>B--->C for example, or if is part some even...