Determine ΔSuniv for the following equation:
Ca2+ (aq) + SO42- (aq) → CaSO4 (s)
You can calculate delta S for the system and delta H for the system at 25 degrees C by using dHo formation and dSo formation and
dHo rxn = (n*dH products) - (n*dH reactants)
dSo rxn = (n*dH products) - (n*dH reactants).
What's the temperature.
dS surrounds = -dH/T
dS system from above
dSuniverse = dSsurroundings + dSsystem.
To determine ΔSuniv (the change in total entropy of the universe) for the given equation, we need to calculate the change in entropy for the system and the surroundings.
The change in entropy for the system, ΔSsys, can be calculated using the formula:
ΔSsys = ∑nS(products) - ∑mS(reactants)
Where n and m are the stoichiometric coefficients of the products and reactants, and S represents the molar entropy of each species.
The change in entropy for the surroundings, ΔSsurr, can be calculated using the formula:
ΔSsurr = -ΔH/T
Where ΔH is the enthalpy change of the reaction (heat exchanged) and T is the temperature in Kelvin.
Since the given equation shows a precipitation reaction (formation of a solid), we know there is an increase in order and a decrease in entropy for the system. The surroundings gain heat, resulting in an increase in their entropy.
To continue, we need to know the values of the molar entropies (S) and the enthalpy change (ΔH) for the reactants and products. These values can be obtained from tables or databases of thermodynamic properties.
Once we have the values, we can substitute them into the formulas mentioned earlier to calculate ΔSsys and ΔSsurr. Finally, we can find ΔSuniv by summing up ΔSsys and ΔSsurr:
ΔSuniv = ΔSsys + ΔSsurr