Calculate S (measure of total entropy) for the following reaction at 25C and 1atm, and tell whether the entropy is increasing or decreasing.
C3H8(g)+5O2(g)-> 3CO2(g)+4H2O(g)
S of C3H8=64.5 cal/(mol*K)
S of O2= 49 cal/(mol*K)
S of CO2= 51.1 cal/(mol*K)
S of H2O= 45.1 cal/(mol*K)
S of the equation is 23.9 and increasing entropy.
I do not know how to factor in the temp. and atm... please help!!!
To calculate the total entropy change (S) for the reaction, you need to use the values of the entropies of the reactants and products. The entropy change can be determined from the difference between the sum of the entropies of the products and the sum of the entropies of the reactants.
The balanced chemical equation is:
C3H8(g) + 5O2(g) -> 3CO2(g) + 4H2O(g)
The given entropies are:
S(C3H8) = 64.5 cal/(mol*K)
S(O2) = 49 cal/(mol*K)
S(CO2) = 51.1 cal/(mol*K)
S(H2O) = 45.1 cal/(mol*K)
To calculate the total entropy change, you can use the following equation:
∆S = ΣS(products) - ΣS(reactants)
∆S = [3S(CO2) + 4S(H2O)] - [S(C3H8) + 5S(O2)]
∆S = [3(51.1) + 4(45.1)] - [64.5 + 5(49)]
∆S = [153.3 + 180.4] - [64.5 + 245]
∆S = 333.7 - 309.5
∆S = 24.2 cal/(mol*K)
Therefore, the total entropy change (S) for the reaction at 25°C and 1 atm is 24.2 cal/(mol*K).
Since the value of S is positive, it indicates an increase in entropy. So, the entropy is increasing in this reaction.
To calculate the total entropy change (ΔS) for a reaction, you need to apply the following formula:
ΔS = ΣS(products) - ΣS(reactants),
where ΣS represents the sum of the entropies of the products and reactants, respectively.
Given:
S(C3H8) = 64.5 cal/(mol*K)
S(O2) = 49 cal/(mol*K)
S(CO2) = 51.1 cal/(mol*K)
S(H2O) = 45.1 cal/(mol*K)
We can substitute these values into the equation to calculate the change in entropy.
ΔS = [3 * S(CO2) + 4 * S(H2O)] - [S(C3H8) + 5 * S(O2)]
= [3 * 51.1 + 4 * 45.1] - [64.5 + 5 * 49]
= [153.3 + 180.4] - [64.5 + 245]
= 333.7 - 309.5
= 24.2 cal/(mol*K)
Therefore, the total entropy change for the reaction is ΔS = 24.2 cal/(mol*K).
Since ΔS is positive, it indicates an increase in entropy during the reaction. Entropy tends to increase when a reactant or product is in a gaseous state, as more possible arrangements are available for gas molecules compared to condensed (liquid or solid) states. In this case, the reaction involves the formation of gaseous products (CO2 and H2O), which leads to an overall increase in entropy.