Matter in Our Surroundings - Phase Changes Experiment

The temperature of the system does not change after the melting point is reached because the heat supplied gets used up in changing the state by overcoming the forces of attraction between the particles, rather than increasing the temperature. This heat energy absorbed by the ice without showing any rise in temperature is known as the latent heat.

The latent heat of fusion is the amount of heat energy required to change 1 kg of a solid into a liquid at its melting point and atmospheric pressure. The latent heat of vaporization is the amount of heat energy required to change 1 kg of a liquid into a gas at its boiling point and atmospheric pressure. The key difference is that the latent heat of fusion is the energy required to change a solid to a liquid, while the latent heat of vaporization is the energy required to change a liquid to a gas.

Particles in steam (water vapor) at 373 K (100°C) have more energy than particles in water at the same temperature of 373 K. This is because the particles in steam have absorbed the extra energy in the form of the latent heat of vaporization during the phase change from liquid to gas.

<p>To convert a temperature on the Celsius scale to the Kelvin scale, you have to add 273 to the given temperature. To convert a temperature on the Kelvin scale to the Celsius scale, you have to subtract 273 from the given temperature. For example, 0°C = 273 K, and 373 K = 100°C.</p> Signup and view all the answers

<p>The melting point is the temperature at which a solid starts changing into a liquid at atmospheric pressure, while the boiling point is the temperature at which a liquid starts changing into a gas at atmospheric pressure. The melting point is reached when the particles have enough energy to break free from the forces of attraction, while the boiling point is reached when particles from the bulk of the liquid gain enough energy to change into the vapor state. These temperatures mark the transition points between the solid-liquid and liquid-gas states, respectively.</p> Signup and view all the answers

<p>During melting, the heat energy supplied increases the kinetic energy of particles, overcoming the attractive forces between them. The particles start vibrating more freely, eventually breaking away from their fixed positions and converting the solid to a liquid state. The melting point is the minimum temperature at which this phase change occurs and is an indication of the strength of attractive forces between the particles.</p> Signup and view all the answers

<p>When a solid melts, the heat energy supplied is used to overcome the attractive forces between particles and facilitate the phase change from solid to liquid state. This energy is absorbed as latent heat of fusion, causing a change in the internal energy and potential energy of the particles, without increasing the temperature.</p> Signup and view all the answers

<p>The change in internal energy (ΔU) during the melting process is given by: ΔU = m × L_f, where m is the mass of the substance and L_f is the latent heat of fusion (the energy required to change the phase from solid to liquid for a unit mass of the substance).</p> Signup and view all the answers

<p>The melting point of a substance is an important physical property that has practical applications in various fields. A high melting point indicates strong intermolecular forces, making the substance suitable for applications that require thermal stability or resistance to melting. Conversely, a low melting point suggests weaker intermolecular forces, which may be desirable for applications involving phase changes or low-temperature processing.</p> Signup and view all the answers

<p>During vaporization, the heat energy supplied increases the kinetic energy of particles in the liquid state, allowing them to overcome the attractive forces and escape the liquid phase into the gaseous state. Unlike melting, where particles only gain enough energy to move freely within the liquid phase, vaporization requires sufficient kinetic energy for particles to completely break away from the liquid phase and become a gas.</p> Signup and view all the answers