The above graph is a phase change diagram for water. At points B and D the water is going through a phase change. During the phase changes, what is happening to the temperature and the heat energy?

Question

The above graph is a phase change diagram for water.  At points B and D the water is going through a phase change.  During the phase changes, what is happening to the temperature and the heat energy?

Bot GPT 3.5 · Answer

During a phase change, such as the ones occurring at points B and D in the graph, the temperature remains constant. This is because the added heat energy is being used to break the intermolecular forces holding the molecules together, rather than increasing the temperature of the substance. At point B, the water is undergoing a phase change from a solid (ice) to a liquid (water). The temperature remains constant at the melting point of water, which is 0 degrees Celsius or 32 degrees Fahrenheit. The heat energy is absorbed by the ice in order to break the intermolecular forces between its molecules and convert it into a liquid. At point D, the water is undergoing a phase change from a liquid to a gas (water vapor). The temperature remains constant at the boiling point of water, which is 100 degrees Celsius or 212 degrees Fahrenheit. The heat energy is absorbed by the water in order to break the intermolecular forces between its molecules and convert it into a gas. In summary, during phase changes, the temperature remains constant while the heat energy is used to break the intermolecular forces and convert the substance from one phase to another.

Step-by-Step Bot · Answer

During phase changes, such as at points B and D on the phase change diagram for water, the temperature remains constant. This means that as the water undergoes a phase change, the amount of heat energy being added or removed does not lead to an increase or decrease in temperature. Instead, this heat energy is used to break or form intermolecular bonds between water molecules. For example, during the solid-to-liquid phase change (melting) at point B, the temperature remains constant at the melting point (0°C) while heat energy is absorbed to break the hydrogen bonds between water molecules and convert the solid ice into liquid water. Similarly, during the liquid-to-gas phase change (vaporization) at point D, the temperature remains constant at the boiling point (100°C) while heat energy is absorbed to break the intermolecular hydrogen bonds and convert the liquid water into water vapor.