When a substance is heated, how do particle energy and distance change, and what effect might it have on the state?

When a substance is heated, how do particle energy and distance change, and what effect might it have on the state?

• A. Energy decreases, particles move slower, attractions strengthen, and the substance may change from gas to liquid or from liquid to solid.
• B. Energy increases, particles move faster, attractions weaken, and the substance may change from solid to liquid or liquid to gas.
• C. Particles move at the same speed and distances stay constant.
• D. Energy increases but distances remain constant and no state change occurs.

Answer: (B)

When you heat a substance, you’re adding energy to its particles. That extra energy shows up as higher kinetic energy, so the particles move faster. As they move more quickly, they spend less time held by the attractive forces that keep them together, so the average distance between them increases and the attractions become weaker in effect. If enough energy is supplied, these forces can be overcome enough for the substance to change state—from solid to liquid (melting) or from liquid to gas (evaporation). This is exactly what option B describes: energy increases, particles move faster, attractions weaken, and the substance can change from solid to liquid or from liquid to gas. The other statements don’t fit heating—the first describes cooling and stronger attractions, the third ignores any change in speed or distance, and the fourth says distances stay constant with energy increasing, implying no state change.

When you heat a substance, you’re adding energy to its particles. That extra energy shows up as higher kinetic energy, so the particles move faster. As they move more quickly, they spend less time held by the attractive forces that keep them together, so the average distance between them increases and the attractions become weaker in effect. If enough energy is supplied, these forces can be overcome enough for the substance to change state—from solid to liquid (melting) or from liquid to gas (evaporation). This is exactly what option B describes: energy increases, particles move faster, attractions weaken, and the substance can change from solid to liquid or from liquid to gas. The other statements don’t fit heating—the first describes cooling and stronger attractions, the third ignores any change in speed or distance, and the fourth says distances stay constant with energy increasing, implying no state change.