Question

Arrange the following in the decreasing order of kinetic energy of molecules.

A) Steam at 101∘C
B) Water at 80∘C
C) Water at 50∘C
D) Ice at −10∘C

Answer 1

The decreasing order of kinetic energy for steam at 101°C, water at 80°C, water at 50°C, and ice at -10°C is steam at 101°C (highest kinetic energy), water at 80°C, water at 50°C, and ice at -10°C (lowest kinetic energy).

Step-by-step explanation:

To arrange steam at 101°C, water at 80°C, water at 50°C, and ice at -10°C in the decreasing order of kinetic energy of molecules, we must consider the states of matter and the temperature of each. The kinetic energy of molecules in a sample depends on both the temperature and the phase of the matter. Generally, in the same phase, a higher temperature indicates higher kinetic energy. When comparing different phases, gases (steam) have the highest kinetic energy, followed by liquids (water), and then solids (ice).

Therefore, the correct order from highest to lowest kinetic energy is:

1. Steam at 101°C: As a gas, the molecules have the most freedom of movement and the highest kinetic energy at this temperature.
2. Water at 80°C: Although it is a liquid and thus has less kinetic energy than steam, water at 80°C has higher kinetic energy than water at a lower temperature.
3. Water at 50°C: Again, as a liquid, it has high kinetic energy, but less so than hotter water.
4. Ice at -10°C: As a solid, the molecules are least free to move and have the lowest kinetic energy.