Question

which statement describes what happens when ice freezes, according to the kinetic theory?
the water molecules decrease their speed.
the water molecules increase their speed.
the water molecules do not change speed.
question 5
1 pts
in what phase, solid, liquid or gas are the particles spread farthest apart and moving freely?
liquid
solid
gas

Explanation:

• For the first question: According to the kinetic theory, when a substance freezes (changes from liquid to solid), the temperature decreases. Temperature is related to the average kinetic energy of particles (\(K.E.=\frac{3}{2}kT\), where \(k\) is the Boltzmann constant and \(T\) is the temperature). As kinetic energy (\(K.E.=\frac{1}{2}mv^{2}\), \(m\) is the mass of the particle and \(v\) is the speed) decreases (because temperature \(T\) decreases during freezing of water), and mass \(m\) of water molecules is constant, the speed \(v\) of water molecules decreases.
• For the second question: In solids, particles are closely packed in a fixed - position lattice. In liquids, particles are close together but can move past one another. In gases, particles have high kinetic energy, and the intermolecular forces are very weak. So, gas particles are spread farthest apart and move freely.

Answer:

• First question: The water molecules decrease their speed.
• Second question: gas.