How do you calculate the enthalpy of formation of methane?
How do you calculate the enthalpy of formation of methane?
1 Answer
- We aim at : C (s) + 2 H2 (g)→ CH4 (g) ; ΔH° =?
- Multiplying eqn. ( ii) with 2, adding to eqn. (
- C (s) + 2H2 (g) – CH4 (g) → 0; ΔrH° = – 393.5 + 2 (–285.8) – (–890.3) – 74.8 kJ mol–1
- or C (s) + 2H2 (g) CH4 (g); ΔrH° = – 74.8 kJ mol–1
- Hence, enthalpy of formation of methane is :
- ΔrH°= – 74.8 kJ mol–1.
What is the enthalpy change of methane?
Enthalpy of Combustion
| Substance | Combustion Reaction | Enthalpy of Combustion, ΔH∘c(kJmolat 25∘C) |
|---|---|---|
| methane | CH4(g)+2O2(g)⟶CO2(g)+2H2O(l) | −890.8 |
| acetylene | C2H2(g)+52O2(g)⟶2CO2(g)+H2O(l) | −1301.1 |
| ethanol | C2H5OH(l)+3O2(g)⟶2CO2(g)+3H2O(l) | −1366.8 |
| methanol | CH3OH(l)+32O2(g)⟶CO2(g)+2H2O(l) | −726.1 |
What is the enthalpy change for the reverse reaction?
Hess’s law The reverse reaction has the negative enthalpy of the forward one.
How do you calculate enthalpy change from formation?
This equation essentially states that the standard enthalpy change of formation is equal to the sum of the standard enthalpies of formation of the products minus the sum of the standard enthalpies of formation of the reactants. and the standard enthalpy of formation values: ΔH fo[A] = 433 KJ/mol. ΔH fo[B] = -256 KJ/mol.
What is the standard enthalpy change of formation of methane CH4 in kJ mol 1?
The standard enthalpy of formation (Δf H° 298) for methane, CH4 is – 74.9 kJ mol–1.
What is the formula of methane gas?
CH₄
Methane/Formula
Methane (US: , UK: ) is a chemical compound with the chemical formula CH4 (one atom of carbon and four atoms of hydrogen). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas.
How do you calculate EA for the reverse reaction?
…the activation energy of the reverse reaction is just the difference in energy between the product(s) (right) and the transition state (hill). Thus, for this endothermic reaction, Ea,rev=Ea,fwd−ΔHrxn .
How do you calculate the enthalpy change of a forward reaction?
The enthalpy of a reaction can be found by calculating the amount of energy required to break the bonds of the reactants, and then subtracting from this value the amount of energy required to form the bonds of the products.
How do you calculate the enthalpy change?
Use the formula ∆H = m x s x ∆T to solve. Once you have m, the mass of your reactants, s, the specific heat of your product, and ∆T, the temperature change from your reaction, you are prepared to find the enthalpy of reaction. Simply plug your values into the formula ∆H = m x s x ∆T and multiply to solve.
How do you calculate the enthalpy change of a solution?
To calculate the enthalpy of solution (heat of solution) using experimental data:
- Amount of energy released or absorbed is calculated. q = m × Cg × ΔT. q = amount of energy released or absorbed.
- calculate moles of solute. n = m ÷ M.
- Amount of energy (heat) released or absorbed per mole of solute is calculated. ΔHsoln = q ÷ n.
What is the ΔfH value for CH4 G in kJ mol?
74.8 kJ mol
The standard enthalpy of formation (ΔfH°) at 298 K for methane, CH4(g), is –74.8 kJ mol–1.