Video Transcript
In the diagram below, the
attractive forces between two molecules in a liquid are indicated by an arrow. The larger the arrow, the stronger
the attractive force. What will these arrows look like if
the liquid undergoes a change of state to a gas?
The particles in a liquid are
moderately spaced apart and free-moving. The particles don’t just drift off
due to moderately strong attractive forces that exist between them. When a liquid gains enough thermal
energy, it can undergo a change of state and become a gas. The particles in a gas have more
energy than those in a liquid and move about more freely, filling the space of the
container they are in. The particles in a gas are more
spread out, and the forces of attraction between them are weaker than in a
liquid.
We are told in the question that
the larger the arrow, the stronger the attractive force. The forces of attraction between
particles in a gas are weaker than in a liquid. So, the arrow should be
smaller. Therefore, the figure that shows
what the arrows will look like if the liquid undergoes a change of state to a gas is
the figure shown in answer choice (A).
