Question

a substance is placed in a closed vessel. the substance is continuously heated and its temperature is monitored, leading to the heating curve below. five regions of the heating curve are labeled with a number. during which region of the graph does the addition of heat cause particles to move about the entire container at even higher speeds?

Explanation:

Step1: Analyze heating curve regions

• Region 1: Heating solid (temperature rises, particles vibrate more).
• Region 2: Melting (phase change, temperature constant, solid to liquid).
• Region 3: Heating liquid (temperature rises, liquid particles move faster).
• Region 4: Boiling (phase change, temperature constant, liquid to gas).
• Region 5: Heating gas (temperature rises, gas particles move about container at higher speeds as heat increases kinetic energy).

Step2: Identify the region

We need the region where heat makes gas particles move faster (since gas particles move about the entire container). After boiling (region 4), region 5 is heating the gas, so adding heat here increases gas particle speed.

Answer:

Region 5