To draw a heating curve for water as it goes from 15°C to 125°C, we need to outline the various phases it transitions through and the associated equations used to calculate the enthalpy changes in each section.
The heating curve will consist of several key segments:
- Heating from 15°C to 0°C (Cooling in Solid Form)
This segment is not part of the heating process but rather reflects the temperature change via specific heat capacity until the freezing point. You would typically not draw this since we start from a liquid, but if considered:
Equation: q = m * c * ΔT - Heating from 0°C to 100°C (Liquid Phase)
In this segment, water is in the liquid phase. The temperature increases as heat is added until it reaches the boiling point:
Equation: q = m * c * ΔT - Phase Change from Liquid to Gas (100°C to 100°C)
At this point, water starts boiling. During this phase change, the temperature remains constant while the water transforms from liquid to gas.
Equation: q = m * ΔH_vap - Heating from 100°C to 125°C (Gas Phase)
After all water has turned to steam, its temperature begins to rise. This is the final segment of heating.
Equation: q = m * c * ΔT
In summary, our heating curve comprises distinct sections representing the changes in state as well as the heat transfer equations relevant for each phase:
- From 15°C to 0°C: solid cooling (if needed).
- From 0°C to 100°C: water as liquid.
- At 100°C: phase change (boiling).
- From 100°C to 125°C: water as gas.
By labeling each portion of the graph accordingly and applying the correct equations, you’ll have a comprehensive heating curve for water over that temperature range.