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Equilibrium Constant Calculator

Equilibrium Constant Calculator

Enter the coefficients and concentrations in their designated fields. The calculator will instantly calculate the equilibrium constant by using its respective chemical equation.

By Using

Concentration: [A]


Coefficient: a

Concentration: [B]


Coefficient: b

Concentration: [C]


Coefficient: c

Concentration: [D]


Coefficient: d

Enter a chemical equation to balance

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Table of Content

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The equilibrium constant calculator will assist you to understand the reversible chemical reactions. The reversible reaction can go in the forward and reverse direction depending upon the molar concentration of the chemical substances involved.

The equilibrium concentration calculator enables us to find how much the reactants and products still remain in the chemical reaction till the stage of equilibrium. It also specifies how long it takes a reaction to reach a stage of equilibrium.

Definition of the Equilibrium Constant:

“The equilibrium constant Kc is the ratio describing the reaction tends to go in forward and reverse direction, meaning all the reactants are converted to the products”. 

The equilibrium is the state at which the number of reactants is equal to the number of the products. We represent the rate of the forward reaction by Kf and the rate of the reverse reaction by the Kc. 

The equilibrium constant calculator guides us to find the direction and the extent of the chemical reaction in a span of moments. This is essential to know in chemical reactions as we know exactly, the exact molar concentration of the reactant to mix in the chemical reaction.

Equilibrium constant equation:

The Equilibrium equation is essential to know the direction of a chemical reaction. After a certain time, an equilibrium stage arrives, meaning the forward reaction (Kf) becomes equal to the rate of the reverse reaction(Kr). At this particular point, we consider that the reaction has reached the equilibrium stage. The equilibrium constant equation is used to represent the (Kc) value.

a[A] + b[B] ⇌ c[C] + d[D]

Kc = ([C]c * [D]d)/([B]b * [A]a)

Kc= Kf/Kr

The graphical representation of Kc:

The graphical representation the equilibrium reaction is the production of nitrogen oxide (NO2) from Dinitrogen tetroxide (N2O4).

(N2O4)g⇌ (NO2)g
The graphical representation of Kc


The concentration of Nitrogen Oxide (NO2) and Dinitrogen tetroxide (N2O4) comes into equilibrium with the passage of time. We can find the value of Kc by an equilibrium constant calculator and predict when  (NO2) and (N2O4) come into the equilibrium stage.

It can be convenient for finding the values of the Kc at any stage of equilibrium by an equilibrium calculator. We can predict how much time the reaction would last.

The Effect of Kc value on the reaction:

We calculate the value of the equilibrium constant Kc, for the reaction. If 0.1908 moles of CO2, 0.0908 moles of H2, 0.009 moles of CO, and 0.0092 moles of H2O vapor present in a “3 L” reaction vessel were present at equilibrium:

Then we can find:

CO2+ H2 ⇌ CO+H2O

Then putting the values in the Kc (equilibrium constant) equation:

Kc = ([CO] [H2O])/([ CO2] [H2])

We are going to find the value of Kc. The Equilibrium constant equation makes it easy to predict the direction of the reaction.

[CO2] = 0.1908 mol CO2/3.00 L = 0.0636 M
[H2] =  0.908 mol H2/3.00 L =0.0303 M
[CO] = 0.009 mol CO/3.00 L =0.0003 M
[H2O] = 0.0092 mol H20/3.00 L =0.0031 M

We can convert the moles into grams by the Moles to Gram Calculator. It can be great to make our calculations just too reliable.

The values of Kc:

Kc=([0.0003] [0.0031])/([0.0636] [0.0303])= 4.825x 10-4

The equilibrium constant calculator automatically finds the value of the Kc.

Calculating the value of KC by ICE:

Iodine molecules react actively and create a condition of equilibrium and produce triiodide ions:

I2(aq)+I-1(aq)⇌  I-13(aq)

In the solution when the concentrations of I2 and I− both equal to 1.000 × 10-3 M before reaction gives an equilibrium concentration of I2 of 6.61 × 10-4M

The equilibrium constant for the reaction:

The equilibrium constant equation is as follows:

Kc = ([ I3])/([ I2] [I-1])

This information is put in the equilibrium constant calculator and derives terms for the equilibrium concentrations of the reactants.

We are presenting all the information in an ICE (Initial concentration of change in  Equilibrium Concentration) table.

I2 (aq)

I− (aq)

  I3− (aq)
Initial Concentration (M) 1 ×10−3 1 ×10−3 0
Change (M) −x −x +x
Equilibrium Concentration (M) 1×10−3 − x 1×10-3 − x x

At equilibrium the concentration of I_2 is 6.61 × 10−4 M so that

 1.000× 10-3 – x = 6.61× 10-4

X= 1.000× 10-3  – 6.61× 10-4

X=3.39× 10-4   M

Now we want to find the Kc by using the ICE Table.

I2 (aq I− (aq) I3− (aq)
Initial Concentration (M) 1× 10−3   1 × 10−3   0
Change (M) −3.39 × 10−4   −3.39 × 10−4     +3.39 × 10-4  
Equilibrium Concentration (M) 6.61 × 10−4    6.61 × 10−4   3.39 × 10−4 

Finally, the equilibrium concentrations can be substituted into the Kc expression and solved:

 Kc = ([I3])/([I2] [I-1])

 Kc = ([  3.39 ×10−4])/([6.61 × 10−4] [6.61 × 10−4 ]) 


The uses of the Kc (equilibrium constant):

By calculating the value of the equilibrium constant, Kc for the reaction, we can predict the following predictions:

  • When Kc=0, it means the equilibrium level has been reached and no forward or reverse reaction is going to happen. 
  • When Kc>0, it means the reaction is going to proceed in the forward direction.
  • When Kc<0, it means the reaction is going to proceed in the reverse direction.

The equilibrium constant expression calculator makes it easy for us to predict the direction of the chemical reaction.

Types of the chemical reactions:

There are two types of the chemical reaction, we are going to elaborate on them:

  • Homogeneous Reactions
  • Heterogeneous Reactions

Homogeneous reactions:

The homogeneous reactions occur when two substances are in the same state of matter. Like gaseous elements reacting with gas, and solid reactions with solids.


The production of methanol from carbon monoxide and hydrogen is a gaseous homogeneous mixture.

CO(g)+ H2(g)⇌ CH3OH(g)

Equilibrium constant calculator assists to produce an exact molar concentration of the methanol.

Heterogeneous reactions:

The heterogeneous reactions occur when two substances of different matter states react with each. Like gaseous elements reacting with solids, or solids reacting with other solids.


The production of Carbon dioxide by mixing the Solid Carbon and gaseous oxygen.

C(s)+ O2(g)⇌ CO2(g)

You need to mix a certain molar concentration of Carbon and Oxygen, we can find the amount of molar concentration in an equilibrium solution calculator.

The extent of the reaction Kc:

The concentration of the Kc also describes the extent of the chemical reaction along with the direction of the chemical reaction.

When Kc value is high:

The very high level of the Kc indicates the reaction would last for a maximum time period. At this level of the Kc, the reactants are going to react with each other spontaneously.


The Kc for the reaction 2O3⇌ 3O2 is= 1 x 1055

The value of the Kc is just too large  1 x 1055

The equilibrium expression calculator guides us about the effect of the large value of Kc.

When the Kc value is small:

The very small level of the Kc constant indicates the reaction is very stable and it is going to complete and not last for a longer time. At this level of the Kc, the reactants are slowly reacting with each other.


The Kc for the reaction 2HF⇌ H2+F2 is =1 x 10-13

The value of the Kc is just too small 1 x 10-13

When the Kc value is moderate:

When the value of the Kc is moderate we conclude the reaction would proceed in a forwards and reverse direction. The reaction is going to attain equilibrium at this stage.


The Kc for the reaction N2+3H2⇌ NH3 is = 10, 

The value of the Kc is moderate here.

How would you know that to calculate keq or Kc, we need just to enter the molar concentrations of the  Nitrogen and Hydrogen in the input field.

Working of the equilibrium constant calculator:


  • For solids and liquid, we need to enter the molar concentration. 
  • For gasses, we need to enter the atmospheric pressure of the gas. 


  • We get the respective value of Kc for solids and liquids 
  • We get the resultant Kp value of the gaseous reaction. 

The equilibrium constant calculator is efficient to calculate the value of the Kc and makes our estimation more reliable.


What is molarity and its unit?

The number of moles of solute per liter of solution. Unit of Molarity is moles/liter or M. The molarity is described in the moles/liter. The molar concentrations can be found by the molarity calculator.

What is the Le charter principle and the effect of change on chemical reaction?

When a change is applied to the chemical reaction like temperature, pressure, or concentration, the equilibrium shifts in the direction that tends to undo the effect of the change.

What are the 3 factors that affect the state of equilibrium?

The temperature, pressure, and concentration can affect the equilibrium. These factors change the state of the equilibrium.

What is the equilibrium state of a chemical reaction?

It is the condition of a system when the energy state remains constant with the passage of time.


The equilibrium constant equation is one of the most useful equations to find the direction or the amount of the products that are going to be produced at a specific time. The equilibrium constant calculator swiftly finds the value of Kc which is critical in finding all the estimations while carrying out chemical reactions in the laboratory. 


From the Source of What is Equilibrium, Types of Equilibrium  

From  What is the equilibrium constant, Kc and Kp

From Equilibrium constant, Competition method, Micro-constants