K Value Calculator

Calculate equilibrium constants Kc or Kp from concentrations or pressures, and estimate pavement k-value from CBR or resilient modulus.

Choose the type of k value you want to calculate. This calculator covers common uses of k, including spring constant, thermal conductivity, equilibrium constant, and first-order reaction rate constant.

Spring k

Thermal k

Equilibrium K

Rate k

Formula: k = F / x. Enter any two values to calculate the missing value.

Spring Constant k N/m

Force F Newtons

Displacement x Meters

Formula: k = qL / (AΔT). Enter any four values to calculate the missing value.

Thermal Conductivity k W/m·K

Heat Transfer Rate q Watts

Thickness L Meters

Area A Square meters

Temperature Difference ΔT K or °C difference

Formula: K = ([C]^c[D]^d) / ([A]^a[B]^b). Use coefficient 0 to ignore a species.

Reactant A Concentration [A]

Reactant A Coefficient a

Reactant B Concentration [B]

Reactant B Coefficient b

Product C Concentration [C]

Product C Coefficient c

Product D Concentration [D]

Product D Coefficient d

Formula: k = ln(C₀ / Cₜ) / t, or k = 0.693 / half-life. Use either concentration over time or half-life.

Initial Concentration C₀ Starting concentration

Final Concentration Cₜ Concentration after time t

Time t Any time unit

Half-Life Use this by itself to calculate k

K Value Formula

The following formula is used to calculate a k value.

K = y / x

Where K is the K value, or vapor-liquid equilibrium ratio.
y is the mole fraction in the vapor
x is the mole fraction in the liquid

To calculate a k-value, divide the mole fraction in the vapor by the mole fraction in the liquid.

K Value Definition

The K value is most often called the vapor-liquid equilibrium constant. It's a ratio of the mole fraction in vapor to the mole fraction in a liquid of vapor to liquid transition or state. This value is derived from Henry's Law and is sometimes called Henry's constant.

Can K values be negative?

In chemistry, as the formula above is used for, k values cannot be negative since you cannot have a negative mole fraction of a substance.

K Value Example

how to calculate k value?

First, determine the mole fraction in the vapor.
Determine the mole fraction of the molecule in a vapor state.
Next, determine the mole fraction in the liquid.
Calculate the mole fraction of the molecule in a liquid state.
Finally, calculate the K Value.
Calculate the K value using the formula above.

FAQ

What is a mole fraction?

A mole fraction is the ratio of the number of moles of one component of a solution to the total moles of all components.