Which of these substances has the highest molar entropy?
A) C2H4 (g)
B) CH3CH2OH (l)
C) SO3 (g)
D) CH3CH3 (g)
E) C6H12O6 (g)
To determine which substance has the highest molar entropy, we need to understand what molar entropy is and how it can be determined for a substance.
Molar entropy (S) is a measure of the disorder or randomness of a substance at a molecular level. It is a thermodynamic property that depends on factors such as the number of particles and the distribution of energy levels among those particles.
The molar entropy of a substance can be calculated using statistical mechanics or can be obtained from tabulated values. In this case, we will rely on tabulated values to compare the molar entropy of the given substances.
Looking at the choices provided:
A) C2H4 (g): Ethylene gas.
B) CH3CH2OH (l): Ethanol liquid.
C) SO3 (g): Sulfur trioxide gas.
D) CH3CH3 (g): Ethane gas.
E) C6H12O6 (g): Glucose gas.
Through a quick comparison, we know that substances in the gaseous state usually have higher molar entropies compared to substances in the liquid or solid states. This is because gases have greater molecular motion and more degree of freedom for molecular arrangements, leading to higher disorder.
Based on this, we can eliminate option B (CH3CH2OH) because it is a liquid.
Next, we can compare the remaining gases. Among options A, C, D, and E, we need to consider the molecular complexity and the number of particles to estimate their molar entropies.
C2H4 (g) (Option A) is composed of two carbon atoms and four hydrogen atoms, resulting in a total of six particles.
SO3 (g) (Option C) is composed of one sulfur atom and three oxygen atoms, totaling four particles.
CH3CH3 (g) (Option D) consists of two carbon atoms and six hydrogen atoms. This leads to a total of eight particles.
C6H12O6 (g) (Option E) is glucose and contains six carbon atoms, twelve hydrogen atoms, and six oxygen atoms. Hence, it has a total of twenty-four particles.
Based on the number of particles, we can deduce that option E (C6H12O6) is the most complex and likely to have the highest molar entropy among the remaining gases.
Therefore, the substance with the highest molar entropy is E) C6H12O6 (g).
To determine which of these substances has the highest molar entropy, we need to compare the molar entropy values for each substance.
The molar entropy of a substance is a measure of the amount of disorder or randomness in its particles at a specific temperature and pressure.
To rank the substances in order of increasing molar entropy, we can consider the following factors:
1. Number and complexity of atoms: Generally, substances with more atoms and greater complexity tend to have higher molar entropy because there are more possible arrangements for the atoms.
2. Physical state: Gases typically have higher molar entropy compared to liquids or solids because the particles are more free to move and have more possible arrangements.
Based on these considerations, let's analyze each substance:
A) C2H4 (g): Ethene is a gas, and it has a relatively larger number of atoms compared to other substances listed. Therefore, it is likely to have a higher molar entropy.
B) CH3CH2OH (l): Ethanol is a liquid. Liquids typically have lower molar entropy compared to gases. Additionally, it has a lower number of atoms compared to C2H4. So, it is likely to have a lower molar entropy compared to C2H4.
C) SO3 (g): Sulfur trioxide is a gas. It contains more atoms than ethanol but fewer than C2H4. Thus, its molar entropy is likely to be between that of ethanol and C2H4.
D) CH3CH3 (g): Ethane is a gas, and it has a similar number of atoms to C2H4. Thus, its molar entropy is expected to be similar to that of C2H4.
E) C6H12O6 (g): Glucose is a gas with a higher number of atoms compared to the other substances listed. Therefore, it is likely to have the highest molar entropy among the options.
Based on this analysis, we can conclude that the substance with the highest molar entropy is E) C6H12O6 (g) or glucose gas.
Liquids < S than gases.
higher molar mass >S than lower molar mass