Chemistry concept
NewTutra Lab · Chemistry
Thermo Forge
Read the energy. Follow the transfer. Predict what becomes favourable.
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Standard reaction profile
Hover or tap the curve, levels and energy arrows.
CH₄ + 2O₂ → CO₂ + 2H₂OHover or tap the curve, levels and energy arrows.
ΔG under conditions−818 kJ mol⁻¹
Equilibrium directionProducts favoured
Expected rateVery slow
ΔH reaction−890 kJ mol⁻¹
Forward Eₐ240 kJ mol⁻¹
Reverse Eₐ1130 kJ mol⁻¹
Use the energy arrows on the graph to calculate enthalpy change and forward and reverse activation energies. Temperature changes the fraction of successful collisions; it does not lower Eₐ.
kJ mol⁻¹
kJ mol⁻¹
kJ mol⁻¹
Read the three vertical arrows.ΔH compares products and reactants; Eₐ measures up to the transition state.
Solution mass, m100.0 g
Specific heat, c4.18 J g⁻¹ °C⁻¹
Temperature change, ΔT+6.5 °C
Reactant amount, n0.050 mol
qsolution = mcΔT
qreaction = −qsolution
ΔH = qreaction ÷ n
qreaction = −qsolution
ΔH = qreaction ÷ n
The solution warms during neutralisation. Calculate the energy gained by the solution, then the molar enthalpy of the reaction.
J
J
kJ mol⁻¹
Track the sign carefully.The surroundings and reacting system transfer equal amounts of energy in opposite directions.
25 °C
ΔH°−890 kJ mol⁻¹
ΔS°−243 J mol⁻¹ K⁻¹
At selected TProducts favoured
Calculate ΔG = ΔH − TΔS. Convert ΔS from joules to kilojoules before subtracting.
kJ mol⁻¹
ΔG < 0 → forward reaction favourable
Temperature can change the result.Watch where the line crosses ΔG = 0.