States of Matter Postlab questions: Your instructor may ask you to answer these in your lab notebook or to answer directly on this page and include these answers in your formal lab report. Follow your instructor’s directions. Draw a diagram representing the changes in physical state for water. Indicate the name of each transition (melting, subliming, etc). Observe your results for water and for the substance you selected in Part 3. How was the last substance similar to water in each state of matter? How was it different? The boiling point of a substance depends on the intermolecular forces (IMF). What IMF are present in oxygen, water, and neon? Investigate what the boiling point of oxygen, water, and neon is. Substance Intermolecular Forces Boiling Point (observed) Oxygen Water Neon Using the table above, explain how different IMF affect the boiling poin
The Correct Answer and Explanation is:
Answer:
1. Diagram of Physical State Changes for Water:
Here is a labeled description for the diagram of water’s phase transitions:
- Solid to Liquid: Melting
- Liquid to Gas: Vaporization (Boiling or Evaporation)
- Gas to Liquid: Condensation
- Liquid to Solid: Freezing
- Solid to Gas: Sublimation
- Gas to Solid: Deposition
A basic version of this could be drawn as a triangle or circle, with water at each state (solid, liquid, gas) and arrows showing the phase changes with labels.
2. Observations – Similarities and Differences:
The substance selected in Part 3 (e.g., isopropyl alcohol) may have been similar to water in that it existed in all three states: solid (when frozen), liquid at room temperature, and gas (when boiled). Like water, it changed states with the addition or removal of heat. However, it may have differed in how quickly it evaporated, its boiling and freezing points, and how it interacted with surfaces. Water has strong hydrogen bonding, so it has a higher boiling point and evaporates more slowly than many other substances.
3. Intermolecular Forces and Boiling Points:
| Substance | Intermolecular Forces | Boiling Point (observed) |
|---|---|---|
| Oxygen | London dispersion forces | -183 degrees Celsius |
| Water | Hydrogen bonding, dipole-dipole | 100 degrees Celsius |
| Neon | London dispersion forces | -246 degrees Celsius |
4. Explanation of IMF and Boiling Points:
The boiling point of a substance depends directly on the strength of its intermolecular forces. Neon and oxygen both exhibit London dispersion forces, which are the weakest type of intermolecular attraction. As a result, they have very low boiling points, with neon boiling at -246 degrees Celsius and oxygen at -183 degrees Celsius. Water, on the other hand, has hydrogen bonding, which is a very strong type of intermolecular force due to the attraction between hydrogen and electronegative oxygen atoms. This leads to a much higher boiling point of 100 degrees Celsius. The stronger the intermolecular forces, the more energy is needed to separate the molecules and convert the liquid into a gas, thus increasing the boiling point. Therefore, water boils at a much higher temperature than neon or oxygen because of the strong hydrogen bonds present.
