Predict the direction of the entropy in each reaction.
a. CaCO3(s)-> CaO(s) +CO2(g0
b. NH3(g)+HCl(g)->NH4Cl(s)
c. 2NaHCO3-> Na2CO3(s)+H20(g) +CO2
d. CaO(s)+CO2(g)-> CaCO3
The secret here is to visualize the randomness of the substances. Entropy increases as we go from solid to liquid to gas. Solids are orderly with atoms essentially locked into place, liquids less orderly and more degrees of freedom for the molecules, gases the molecules can go every which way.
a. CaCO3 is solid, CaO is solid BUT CO2 is a gas so entropy increases in going from left to right.
b. gases going to solid; entropy decreases from left to right.
Positive
To determine the direction of entropy in each reaction, we need to consider the change in the number of moles of gas and the change in the state of matter.
a. CaCO3(s) -> CaO(s) + CO2(g)
In this reaction, the reactant (CaCO3) is a solid, and the products (CaO and CO2) include one gas. Since the number of moles of gas increases from 0 (solid) to 1 (gas), the entropy of the system increases. Therefore, the direction of entropy is positive.
b. NH3(g) + HCl(g) -> NH4Cl(s)
In this reaction, both reactants (NH3 and HCl) are gases, and the product (NH4Cl) is a solid. The number of moles of gas decreases from 2 (gases) to 0 (solid), leading to a decrease in entropy. Therefore, the direction of entropy is negative.
c. 2NaHCO3 -> Na2CO3(s) + H2O(g) + CO2(g)
In this reaction, the reactant (2NaHCO3) is a solid, and the products (Na2CO3, H2O, and CO2) include two gases. The number of moles of gas increases from 0 (solid) to 2 (gases), resulting in an increase in entropy. Therefore, the direction of entropy is positive.
d. CaO(s) + CO2(g) -> CaCO3(s)
In this reaction, the reactant (CO2) is a gas, and the product (CaCO3) is a solid. The number of moles of gas decreases from 1 (gas) to 0 (solid), leading to a decrease in entropy. Therefore, the direction of entropy is negative.
To predict the direction of entropy in each reaction, we need to consider the changes in the physical state and number of molecules.
a. CaCO3(s) -> CaO(s) + CO2(g)
In this reaction, a solid (CaCO3) is converted into a solid (CaO) and a gas (CO2). The number of molecules is decreasing, as one solid converts into another solid and a gas is released. Since the gas phase is more disordered than the solid phase, the entropy is expected to increase. Therefore, the direction of entropy is positive (+).
b. NH3(g) + HCl(g) -> NH4Cl(s)
In this reaction, two gases (NH3 and HCl) react to form a solid (NH4Cl). The number of molecules is decreasing, as two gases combine to form a solid. Since the solid state is less disordered than the gas phase, the entropy is expected to decrease. Therefore, the direction of entropy is negative (-).
c. 2NaHCO3 -> Na2CO3(s) + H2O(g) + CO2
In this reaction, a solid (NaHCO3) decomposes to form a solid (Na2CO3), a gas (CO2), and a gas (H2O). The number of molecules is increasing, as one solid decomposes into a solid and two gases. Since the gas phase is more disordered than the solid phase, the entropy is expected to increase. Therefore, the direction of entropy is positive (+).
d. CaO(s) + CO2(g) -> CaCO3
In this reaction, a solid (CaO) reacts with a gas (CO2) to form a solid (CaCO3). The number of molecules is decreasing, as one gas reacts with a solid to form another solid. Since the solid state is less disordered than the gas phase, the entropy is expected to decrease. Therefore, the direction of entropy is negative (-).
Remember, these predictions are based on general trends and assumptions. Detailed calculations and experimental data can provide more accurate information on the changes in entropy for specific reactions.