Question

Draw a heating curve for a sample of ice that is heated from \(-20^{\circ} \mathrm{C}\) to \(150^{\circ} \mathrm{C}\). Indicate the segment of the graph that corresponds to each of the following: a. solid b. melting c. liquid d. boiling e. gas

Short answer

Draw segments a (solid) from (-20℃ to 0℃), b (melting) at 0℃, c (liquid) from 0℃ to 100℃, d (boiling) at 100℃, and e (gas) from 100℃ to 150℃.

Step-by-step solution

Understand the Heating Curve

A heating curve shows the change in temperature of a substance as heat is added. The key points on a heating curve include segments where the temperature increases and segments where phase changes occur at a constant temperature.

Define the Temperature Ranges and Phases

Identify the temperature ranges for the different phases of water: solid (ice) from (-20℃ to 0℃), melting point at 0℃, liquid (water) from 0℃ to 100℃, boiling point at 100℃, and gas (steam) from 100℃ onwards.

Process for Drawing the Heating Curve

1. Start the graph at (-20℃).2. Draw a sloped line from (-20℃ to 0℃) (Segment a – solid).3. Draw a horizontal line at 0℃ (Segment b – melting).4. Draw another sloped line from 0℃ to 100℃ (Segment c – liquid).5. Draw a horizontal line at 100℃ (Segment d – boiling).6. Finally, draw a sloped line from 100℃ to 150℃ (Segment e – gas).

Label Each Segment

Label each segment as follows:- Segment a: Solid (ice)- Segment b: Melting- Segment c: Liquid (water)- Segment d: Boiling- Segment e: Gas (steam)

Key concepts

phase changes

Phase changes refer to the transition of matter from one state to another. These changes occur when energy, in the form of heat, is added or removed from a substance. The main phase changes we observe include:
- Melting: Transition from solid to liquid
- Freezing: Transition from liquid to solid
- Boiling: Transition from liquid to gas
- Condensation: Transition from gas to liquid
- Sublimation: Transition from solid directly to gas
- Deposition: Transition from gas directly to solid
During these transitions, the temperature of the substance remains constant even though heat is being added or removed. This is because the energy is used to change the state rather than temperature.

temperature ranges

Temperature ranges indicate the specific temperatures at which a substance exists in different states. For water, the temperature ranges for its phases are as follows:
- Solid (ice): Below 0°C
- Liquid (water): From 0°C to 100°C
- Gas (steam): Above 100°C
Each phase has a range where temperatures remain relatively stable. The heating curve of water showcases these ranges clearly, with flat portions representing phase changes and sloped portions indicating heating within a specific phase.

solid liquid gas transitions

Transitions among solid, liquid, and gas states are fundamental to understanding heating curves. Here’s what happens during these transitions:
- Solid to Liquid (Melting): Heat energy breaks the structured arrangement of particles in ice, converting it to liquid water.
- Liquid to Gas (Boiling): Heat energy further breaks the intermolecular bonds, allowing water molecules to move freely as steam.
- Gas to Liquid (Condensation): Removal of heat causes steam to lose energy and revert to water.
- Liquid to Solid (Freezing): Further heat removal results in water molecules arranging themselves into a solid structure, forming ice.
Each transition requires or releases a specific amount of energy, and the temperature remains constant during this process.

melting point

The melting point is the specific temperature at which a solid turns into a liquid. For water, this happens at 0°C. On a heating curve:
- The segment representing melting is horizontal at the melting point temperature,
- This flat line signifies that the temperature remains constant as the ice absorbs heat to transform into liquid water.
The energy absorbed during this period is called the latent heat of fusion, which is essential to overcome the forces holding the particles together in a solid state.

boiling point

The boiling point is the temperature at which a liquid turns into a gas. For water, this is at 100°C at standard atmospheric pressure. During the boiling process:
- The heating curve shows a horizontal line at the boiling point temperature;
- This indicates that the temperature remains constant while the liquid water absorbs heat and transitions into steam.
The energy required for this transformation is known as the latent heat of vaporization, which is necessary to break the intermolecular forces holding the liquid together. Understanding the boiling point allows us to predict and explain the energy changes that occur during heating and cooling processes.