For the organic compound "Vanillin" (C8H8O3):
1) If the standard state is a "solid" EXPLAIN why Vanillin starts out as a solid?
2) If the vapor pressure for Vanillin is: 1.18X10-4 mm Hg at 25 °C. Would you consider it to have a "high" or "low" vapor pressure? (explain your reasoning).
3) If the melting point for Vanillin is: 81 C (178 F, 354 K) to 83 C (181 F, 356 K) and Boiling Point is: 285 C (545 F, 558 K). Would you consider it to have a "high" or "low"? (explain your reasoning).
1. With a melting point of 81 C and room termperature being about 25 C, why wouldn't the "standard" state be a solid?
2. I looked up the vapor pressure of naphthalene @ 27 C (a little above room temperature pf 25 C) and found it to be 0.0945 mm Hg. We know naphthalene "smells" to high heaven. So if this solid has a vapor pressure of 0.000118 mm Hg, which is about 1000 times less than that of naphthalene, I would not consider that to be high but I suppose high vs low is relative and depends upon the observer.
3. I don't get #3. high or low what?
1) Vanillin starts out as a solid in its standard state due to the molecular structure and intermolecular forces present in the compound. Vanillin consists of eight carbon atoms, eight hydrogen atoms, and three oxygen atoms. The arrangement of these atoms in a solid state allows for strong intermolecular forces, such as hydrogen bonding and dipole-dipole interactions, to occur between the molecules. These intermolecular forces hold the molecules together in a solid lattice structure, giving vanillin its solid state at room temperature.
2) Based on the given vapor pressure of 1.18x10^(-4) mm Hg at 25 °C, we can consider vanillin to have a relatively low vapor pressure. Vapor pressure is a measure of a substance's tendency to evaporate or transition from a liquid or solid to a gas. A high vapor pressure suggests that a substance evaporates easily, while a low vapor pressure indicates that it evaporates slowly. The given value of 1.18x10^(-4) mm Hg is quite small, implying that vanillin evaporates slowly at 25 °C.
3) Comparing the melting point and boiling point of vanillin, we can consider it to have a relatively high boiling point. The melting point range of 81 °C to 83 °C suggests that vanillin requires a relatively high temperature to transition from a solid to a liquid state. This indicates that the intermolecular forces holding vanillin's solid lattice structure together are relatively strong. The boiling point of 285 °C further indicates that a significant amount of energy is required to break these intermolecular forces and convert vanillin from a liquid to a gas. Therefore, vanillin is considered to have a high boiling point compared to substances with lower boiling points.
1) Vanillin starts out as a solid in its standard state because the intermolecular forces between its molecules are strong enough to hold them in a defined, organized arrangement. In the solid state, the vanillin molecules are closely packed together, forming a crystal lattice structure. The intermolecular forces such as hydrogen bonding and dipole-dipole interactions between the molecules are responsible for the stability and rigidity of this solid structure. These forces are stronger than the thermal energy at normal temperatures, which prevents the molecules from separating and moving freely, resulting in a solid state.
2) To determine whether the vapor pressure of vanillin is high or low, we can compare its value to those of other substances at the same temperature. A high vapor pressure indicates that a substance readily transitions from the liquid or solid phase to the gas phase. Conversely, a low vapor pressure suggests that the substance has a tendency to remain in the condensed states (liquid or solid).
In this case, the vapor pressure of vanillin is given as 1.18 x 10-4 mm Hg at 25 °C. Although there is no strict threshold for what constitutes high or low vapor pressure, vanillin's value is relatively low compared to many other common substances at room temperature. For example, water has a vapor pressure of around 23.8 mm Hg at 25 °C, while ethanol has a vapor pressure of about 60 mm Hg. Given this, we can conclude that vanillin has a low vapor pressure because it does not readily evaporate at room temperature.
3) The melting point and boiling point of a substance provide information about its intermolecular forces and the energy required to overcome them. A high melting point and boiling point typically indicate strong intermolecular forces.
Vanillin has a melting point range of 81 °C to 83 °C (178 °F to 181 °F, 354 K to 356 K). This range suggests that vanillin requires a relatively high temperature to transition from the solid to the liquid phase, indicating that it has strong intermolecular forces holding its solid form together. Similarly, the boiling point of vanillin is 285 °C (545 °F, 558 K), which is relatively high compared to many common organic compounds.
Based on these values, we can conclude that vanillin has a high melting point and boiling point, indicating strong intermolecular forces between its molecules. These could be attributed to factors such as hydrogen bonding, dipole-dipole interactions, or aromatic interactions present in the vanillin molecule.