To get the best deal on Tutoring, call 1-855-666-7440 (Toll Free)
Top

Enthalpy Calculator
Top
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

Back to Top
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

Back to Top
  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



    Answer  :  

    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



    Answer  :  

    Enthalpy(Qp) = 2104



*AP and SAT are registered trademarks of the College Board.