Which change happens when a substance melts?
o Hear energy overcomes the forces of attraction between the molecules of the substance so the molecules can move more freely.
o The molecules of the substance move farther apart which pulls on the intermolecular bonds between them.
o The vibration of the molecules produces enough heat to weaken the forces of attraction between the molecules of the substance.
o Heat energy forces the molecules of the substance farther apart until the rigid structure of the solid breaks.
I think a is right (partly) and I also think d is right (partly) but in my opinion both a and d could be expressed more clearly. Heat increases the kinetic energy of the molecules, they can move more freely and more energetically, and at some point the attractive forces between the molecules is too small to hold them together and the rigid structure of the solid is broken.
The correct answer is:
Heat energy overcomes the forces of attraction between the molecules of the substance so the molecules can move more freely.
The correct answer is that heat energy overcomes the forces of attraction between the molecules of the substance so the molecules can move more freely.
To understand why this change happens when a substance melts, we need to consider the molecular structure and the behavior of molecules. In a solid state, the molecules are held together by intermolecular forces, such as Van der Waals forces or hydrogen bonding, which create a rigid structure. These forces hold the molecules in a fixed position, causing the substance to maintain its shape.
When heat is applied to a solid, the temperature of the substance increases. As the temperature rises, the kinetic energy of the molecules also increases. This increased kinetic energy allows the molecules to vibrate and move more rapidly.
As the heat energy continues to be transferred to the substance, it eventually reaches a point where it overcomes the intermolecular forces. At this point, the molecules have enough energy to break free from their fixed positions and move more freely. This transition from a solid to a liquid state is known as melting.
During melting, the molecules gradually begin to move farther apart, leading to a more disordered arrangement compared to the solid state. The intermolecular bonds or forces between the molecules become weaker or are completely overcome by the heat energy. This increased molecular motion and weakened intermolecular forces allow the substance to flow and take on the shape of its container, forming a liquid.