Question

Dry ice on heating produces :

• A. Liquid \(\text{CO}_2\)
• B. Gas \(\text{CO}_2\)
• C. Liquid water
• D. Water vapour

Hint:

Dry ice is solid Carbon Dioxide (\(\text{CO}_2\)). Its special property is that at normal atmospheric pressure, it doesn't melt into a liquid. Instead, it {sublimes} ��� it turns directly from a solid into a gas. So, Dry ice (solid \(\text{CO}_2\)) \(\xrightarrow{\text{Heating/Room Temp}}\) \(\text{CO}_2\) gas. This is why it's called "dry" ��� no wet liquid phase.

Answer 1

The Correct Option is B

Concept: Dry ice is the solid form of carbon dioxide (\(\text{CO}_2\)). Its behavior upon heating at atmospheric pressure is characterized by a specific phase transition. Step 1: What is Dry Ice? Dry ice is solid carbon dioxide (\(\text{CO}_2\)). It is called "dry" ice because it does not melt into a liquid at atmospheric pressure. Step 2: Phase Transition of Dry Ice at Atmospheric Pressure At standard atmospheric pressure (around 1 atm), solid carbon dioxide undergoes sublimation when heated or left at room temperature. Sublimation is the direct transition from the solid phase to the gas phase without passing through an intermediate liquid phase. The sublimation point of dry ice at 1 atm pressure is \(-78.5^\circ\text{C}\) (\(-109.3^\circ\text{F}\)). So, when dry ice is "heated" (meaning its temperature is raised above its sublimation point, or even just exposed to room temperature which is much higher), it changes directly into gaseous carbon dioxide (\(\text{CO}_2\) gas). Step 3: Can Liquid \(\text{CO}_2\) be formed? Liquid carbon dioxide can exist, but only under pressures greater than its triple point pressure, which is approximately 5.11 atm (5.18 bar). At normal atmospheric pressure, \(\text{CO}_2\) transitions directly between solid and gas. Step 4: Analyzing the options
(1) Liquid \(\text{CO}_2\): Not formed at normal atmospheric pressure upon heating dry ice.
(2) Gas \(\text{CO}_2\): Correct. Dry ice sublimes to form gaseous carbon dioxide.
(3) Liquid water: Incorrect. Dry ice is solid \(\text{CO}_2\), not frozen water.
(4) Water vapour: Incorrect. Dry ice does not contain water. Therefore, dry ice on heating (at atmospheric pressure) produces gaseous \(\text{CO}_2\).