Question

1. *carbon dioxide has a formula of co₂. use this knowledge to represent phase changes from solid to liquid to gas of a sample of carbon dioxide. label each phase and create a key showing an atom of co₂. drawing box and key box 2. nitrogen (n₂) is in the liquid state at an extremely cold temperature. it boils at -195.79°c (-320°f) and freezes at -210 °c (-346 °f). liquid nitrogen is typically contained in vacuum flasks, called dewars, which allows the nitrogen to remain cooler than its surroundings. once released to atmospheric conditions, liquid nitrogen boils and is released as a gas, but can cause rapid solidification on contact with living tissue. in the space provided, draw a particle diagram to represent given scenarios. your response must include at least four molecules in each phase. drawing boxes with vacuum flasks and labels the dewar shown above is kept in an industrial freezer in the lab. the temperature of the freezer averages -201°c. show the two phases of nitrogen that exist when the rubber stopper is taken off of the dewar. the temperature in the lab is around 23°c.

Explanation:

Problem 1 (Carbon Dioxide Phase Changes)

To represent the phase changes of \( \text{CO}_2 \) (solid → liquid → gas) and create a key:

1. Solid Phase (Dry Ice): In the solid phase, \( \text{CO}_2 \) molecules are closely packed in a regular, repeating pattern. Draw small, closely spaced \( \text{CO}_2 \) symbols (using the key symbol) in an orderly, compact arrangement.
2. Liquid Phase: Liquid \( \text{CO}_2 \) molecules are still close together but can slide past one another (less ordered than solid). Draw \( \text{CO}_2 \) symbols with a bit more space between them, arranged somewhat randomly but still relatively close.
3. Gas Phase: Gaseous \( \text{CO}_2 \) molecules are far apart and move freely. Draw \( \text{CO}_2 \) symbols widely spaced, with arrows or motion lines to indicate movement.
4. Key: The key already labels \( \boldsymbol{\text{■} = \text{CO}_2} \), so ensure the symbol is consistent across all phases.

Problem 2 (Nitrogen Phase Diagrams)

Part 1: Dewar in Industrial Freezer (\( \boldsymbol{-201^\circ \text{C}} \))

The freezer temperature (\( -201^\circ \text{C} \)) is between nitrogen’s freezing point (\( -210^\circ \text{C} \)) and boiling point (\( -195.79^\circ \text{C} \)). Thus, nitrogen is a liquid here.

• Draw at least 4 \( \text{N}_2 \) molecules (using the key \( \boldsymbol{\text{●●} = \text{N}_2} \)) closely packed (liquid structure) inside the Dewar.

Part 2: Dewar with Stopper Removed (Lab Temp \( \boldsymbol{23^\circ \text{C}} \))

Lab temperature (\( 23^\circ \text{C} \)) is above nitrogen’s boiling point (\( -195.79^\circ \text{C} \)). When the stopper is removed, liquid nitrogen boils into gas, but some may still be liquid (or rapidly solidify on tissue, but the problem focuses on phases in the Dewar/air).

• Liquid Phase (inside Dewar): Draw 4+ \( \text{N}_2 \) molecules closely packed (liquid).
• Gas Phase (outside Dewar/air): Draw 4+ \( \text{N}_2 \) molecules widely spaced (gas, with motion lines if desired).

Final Answer (Diagram Guidance)

For both problems, use the provided key symbols to draw:

1. \( \text{CO}_2 \): Solid (compact, ordered) → Liquid (closer, less ordered) → Gas (spread out, moving).
2. \( \text{N}_2 \): Liquid (freezer) → Liquid + Gas (lab, after opening).

(Note: Since these are diagram - based, the answer is the visual representation following the phase - particle arrangement rules above.)

Answer:

To represent the phase changes of \( \text{CO}_2 \) (solid → liquid → gas) and create a key:

1. Solid Phase (Dry Ice): In the solid phase, \( \text{CO}_2 \) molecules are closely packed in a regular, repeating pattern. Draw small, closely spaced \( \text{CO}_2 \) symbols (using the key symbol) in an orderly, compact arrangement.
2. Liquid Phase: Liquid \( \text{CO}_2 \) molecules are still close together but can slide past one another (less ordered than solid). Draw \( \text{CO}_2 \) symbols with a bit more space between them, arranged somewhat randomly but still relatively close.
3. Gas Phase: Gaseous \( \text{CO}_2 \) molecules are far apart and move freely. Draw \( \text{CO}_2 \) symbols widely spaced, with arrows or motion lines to indicate movement.
4. Key: The key already labels \( \boldsymbol{\text{■} = \text{CO}_2} \), so ensure the symbol is consistent across all phases.

Problem 2 (Nitrogen Phase Diagrams)

Part 1: Dewar in Industrial Freezer (\( \boldsymbol{-201^\circ \text{C}} \))

The freezer temperature (\( -201^\circ \text{C} \)) is between nitrogen’s freezing point (\( -210^\circ \text{C} \)) and boiling point (\( -195.79^\circ \text{C} \)). Thus, nitrogen is a liquid here.

• Draw at least 4 \( \text{N}_2 \) molecules (using the key \( \boldsymbol{\text{●●} = \text{N}_2} \)) closely packed (liquid structure) inside the Dewar.

Part 2: Dewar with Stopper Removed (Lab Temp \( \boldsymbol{23^\circ \text{C}} \))

Lab temperature (\( 23^\circ \text{C} \)) is above nitrogen’s boiling point (\( -195.79^\circ \text{C} \)). When the stopper is removed, liquid nitrogen boils into gas, but some may still be liquid (or rapidly solidify on tissue, but the problem focuses on phases in the Dewar/air).

• Liquid Phase (inside Dewar): Draw 4+ \( \text{N}_2 \) molecules closely packed (liquid).
• Gas Phase (outside Dewar/air): Draw 4+ \( \text{N}_2 \) molecules widely spaced (gas, with motion lines if desired).

Final Answer (Diagram Guidance)

For both problems, use the provided key symbols to draw:

1. \( \text{CO}_2 \): Solid (compact, ordered) → Liquid (closer, less ordered) → Gas (spread out, moving).
2. \( \text{N}_2 \): Liquid (freezer) → Liquid + Gas (lab, after opening).

(Note: Since these are diagram - based, the answer is the visual representation following the phase - particle arrangement rules above.)