To determine which substance would need to be cooled to the lowest temperature before it condenses, we need to examine their boiling points. The boiling point is the temperature at which a substance changes from a liquid to a gas, and the same temperature is required for the reverse process, i.e., condensing from gas to liquid.
1. Ammonia ([tex]$NH_3$[/tex]):
- Boiling point: [tex]\(-33.34\)[/tex] degrees Celsius
2. Ethane ([tex]$C_2H_6$[/tex]):
- Boiling point: [tex]\(-88.5\)[/tex] degrees Celsius
3. Potassium Bromide ([tex]$KBr$[/tex]):
- Boiling point: [tex]\(1435\)[/tex] degrees Celsius
To find which substance needs to be cooled the most (to the lowest temperature) before it condenses from a gas to a liquid, we need to identify the substance with the lowest boiling point.
Here are the boiling points again for clarity:
- Ammonia: [tex]\(-33.34\)[/tex] degrees Celsius
- Ethane: [tex]\(-88.5\)[/tex] degrees Celsius
- Potassium Bromide: [tex]\(1435\)[/tex] degrees Celsius
Among these values, [tex]\(-88.5\)[/tex] degrees Celsius is the lowest boiling point. Therefore, the substance that would need to be cooled to the lowest temperature before it condenses is:
- Ethane ([tex]$C_2H_6$[/tex])
So, the answer is ethane.
