Question

Using the thermodynamic information provided, calculate the standard reaction entropy (ΔS°) for the chemical reaction:

SnO₂+2CO→Sn(s,White)+2CO₂
a) Determine the standard molar entropy (S⁰) for each reactant and product.
b) Calculate the change in molar entropy for each species involved in the reaction.
c) Sum the changes in molar entropy to find the overall change in entropy for the reaction.
d) Use the calculated values to determine the standard reaction entropy (ΔS⁰).

Answer 1

The standard reaction entropy (ΔS°) is calculated by determining standard molar entropy (S°) for each substance, calculating the entropy change for each substance, summing these changes, and using the 'products minus reactants' rule to determine ΔS°.

Step-by-step explanation:

To calculate the standard reaction entropy (ΔS°) for the chemical reaction SnO₂ + 2CO → Sn(s, White) + 2CO₂, follow these steps:

1. Determine the standard molar entropy (S°) for each reactant and product using tabulated values at 298.15 K and 1 bar pressure.
2. Calculate the change in molar entropy (ΔS) for each species by using the formula: ΔS° = nSº(products) - mS°(reactants), where n and m are the stoichiometric coefficients in the balanced equation.
3. Sum the changes in molar entropy to find the overall change in entropy (ΔS°) for the reaction by adding the entropies of the products and subtracting the entropies of the reactants, each multiplied by their respective coefficients in the balanced equation.
4. Use the calculated values to determine ΔS°, which represents the standard reaction entropy change.

An example calculation similar to this is given by: ΔS° = 2*S°(NH₃) - [S°(N₂) + (3*S°(H₂))] resulting in ΔS° = -198.3 J/mol·K.