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Enthalpy Calculator
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Enthalpy Calculator is an online tool for calculating Enthalpy easily. It takes the inputs and calculates the Enthalpy, so it is handy for solving problems requiring Enthalpy Calculations.

Enthalpy Formula: Enthalpy(Qp) = $\Delta{E}$ + P$\Delta{V}$
Where,
$\Delta{E}$ = Change in Internal Energy = Internal Energy of Products(Ep) - Internal Energy of Reactants(Er)
P = Pressure of the System
$\Delta{V}$ = Change in Volume = Volume of Products(Vp) - Volume of Reactants(Vr).

## Steps for Enthalpy Calculator

Step 1 :

Observe the value of change in internal energy, pressure and change in volume.

Step 2 :

Apply the formula:

Enthalpy(Qp) = $\Delta{E}$ + P$\Delta{V}$
Where,
$\Delta{E}$ = Change in Internal Energy = Internal Energy of Products(Ep) - Internal Energy of Reactants(Er)
P = Pressure of the System
$\Delta{V}$ = Change in Volume = Volume of Products(Vp) - Volume of Reactants(Vr).

## Problems on Enthalpy Calculator

1. ### When 5 gram of alcohol boils at 1 atm (alcohol boiling at 65$^{\circ}C$), the volume of the alcohol is found to be 4.5 L more than the volume of the liquid. The heat transfer is 5865 joule and is found to be an endothermic process. Calculate the change in heat. (1 L atm = 101.3 Joules)

Step 1 :

The process takes place at constant pressure and so delta H = Qp and as thermal energy is absorbed to the system the sign of delta H would be positive.

Step 2 :

So delta H = 5865 joule and as the system expands the change in volume or delta V is also +ve.

W(atm ) = -P($\Delta{V}$) = -1 atm x 4.5 L = - 4.5 L atm

W (atm) = - 4.5 x 101.3 joules = - 455.85 joules

Delta E = Qp + W (atm)= 5865 j – 455.85 j = 5409.15 j

5409.15 j

2. ### If the internal energy and volume of products and reactants are 234 joules, 130 joules, 20 cubic meters and 10 cubic meters, then calculate the respective enthalpy for a pressure of 200 pascals?

Step 1 :

Given that:

Internal Energy of Products(Ep) = 234 joules

Internal Energy of Reactants(Er) = 130 joules

Volume of Products(Vp) = 20 cubic meters

Volume of Reactants(Vr) = 10 cubic meters

Pressure(P) = 200 pascals

Enthalpy(Qp) = ?

Step 2 :

We know that:

Enthalpy(Qp) = $\Delta{E}$ + P$\Delta{V}$

Enthalpy(Qp) = Ep - Er + P(Vp - Vr)

Enthalpy(Qp) = 234 J - 130 J + 200 Pa (20$m^3$ - 10$m^3$)

Enthalpy(Qp) = 104 J + 200 Pa(10$m^3$) = 2104 J