🔥 Enthalpy Diagram Thermochemistry Visualizer
ThermochemistryWhat's happening? ΔH = H(products) - H(reactants). Exothermic: products lower than reactants, heat released. Endothermic: products higher, heat absorbed. Ea is the energy barrier.
Thermochemistry: 3-5 questions every year.
JEE tests enthalpy, calorimetry, Hess's law, bond energies.
Key formulas
Enthalpy Diagrams Formulas
First law
dU = q + w
Internal energy = heat + work ON system
Enthalpy
dH = dU + d(PV) = q_p
At constant P, dH = heat
Hess's law
dH_total = dH1 + dH2 + ...
Path-independent
Bond enthalpy
dH = sum(BDE_react) - sum(BDE_prod)
Break minus form
Step-by-step problem solving
How to solve chemistry problems in JEE
- Identify given reactions and dH
- Manipulate to get target reaction
- Sum dH with correct signs
- Calorimetry: q = mc*dT, dH = q/n
Common JEE mistakes
What students get wrong
Hess sign error
Reverse flips sign, double doubles dH
System vs surroundings
Exothermic: dH<0, q(surr)>0
Wrong heat capacity
Water: c = 4.18 J/gC
Ignore dNg
dH = dU + dNg*RT for gases
FAQs
Enthalpy Diagrams Questions
dH vs dU?
dH = dU + d(PV). At constant P: dH = q. No dNg: dH = dU.
Exothermic vs endothermic?
Exothermic: products lower (dH<0). Endothermic: higher (dH>0)
q = mcdT vs q = CdT?
mcdT for substances, CdT for calorimeters
Kirchhoff equation?
dH(T2) = dH(T1) + Cp*(T2-T1)