Calculate δh for the reaction 2SO2(g) + O2(g) → 2SO3(g)
Introduction & Importance
Calculating the change in enthalpy (δh) for the reaction 2SO2(g) + O2(g) → 2SO3(g) is crucial in understanding the energy change during this exothermic process. This calculator and guide will help you determine δh and provide insights into the reaction’s energetics.
How to Use This Calculator
- Enter the amounts of SO2 and O2 in grams.
- Click the “Calculate” button.
- View the results below the calculator.
Formula & Methodology
The change in enthalpy (δh) can be calculated using the following formula:
δh = ΣΔHf°(products) - ΣΔHf°(reactants)
Where ΔHf° is the standard enthalpy of formation. The values for SO2, O2, and SO3 are -296.8, 0, and -395.7 kJ/mol, respectively.
Real-World Examples
Example 1: 50g of SO2 and 25g of O2
δh = [2 * (-395.7) – (50 * (-296.8) + 25 * 0)] kJ
Example 2: 100g of SO2 and 50g of O2
δh = [2 * (-395.7) – (100 * (-296.8) + 50 * 0)] kJ
Example 3: 75g of SO2 and 37.5g of O2
δh = [2 * (-395.7) – (75 * (-296.8) + 37.5 * 0)] kJ
Data & Statistics
Standard Enthalpies of Formation (ΔHf°)
| Substance | ΔHf° (kJ/mol) |
|---|---|
| SO2 | -296.8 |
| O2 | 0 |
| SO3 | -395.7 |
Reaction Enthalpies (ΔHrxn)
| Amount of SO2 (g) | Amount of O2 (g) | δh (kJ) |
|---|---|---|
| 50 | 25 | -197.6 |
| 100 | 50 | -395.2 |
| 75 | 37.5 | -296.4 |
Expert Tips
- Always use the most recent and accurate ΔHf° values for your calculations.
- Consider the effect of temperature on δh, as it is not constant.
- For more complex reactions, consider using a thermochemical table or software.
- To convert grams to moles, use the molar mass of the substance.
- For mixtures, calculate the total mass and convert it to moles.
Interactive FAQ
What is the molar mass of SO2?
The molar mass of SO2 is 64.06 g/mol.
Why is the reaction exothermic?
The reaction is exothermic because the enthalpy of formation of SO3 is more negative than that of SO2, resulting in a decrease in enthalpy during the reaction.
PubChem – Enthalpy of Formation
Chemistry StackExchange – Standard Enthalpy of Formation of SO2