explain why there is no rise in temperature of a substance when it undergoes a change of state through it is being continuously heated
Answers
Answer:
itt is called as sublimation
Heat, \text qqq, is thermal energy transferred from a hotter system to a cooler system that are in contact.
Temperature is a measure of the average kinetic energy of the atoms or molecules in the system.
The zeroth law of thermodynamics says that no heat is transferred between two objects in thermal equilibrium; therefore, they are the same temperature.
We can calculate the heat released or absorbed using the specific heat capacity \text CCC, the mass of the substance \text mmm, and the change in temperature \Delta \text TΔTdelta, T in the equation:
\text q = \text {m} \times \text C \times \Delta \text Tq=m×C×ΔTq, equals, m, times, C, times, delta, T
Heat in thermodynamics
What contains more heat, a cup of coffee or a glass of iced tea? In chemistry class, that would be a trick question (sorry!). In thermodynamics, heat has a very specific meaning that is different from how we might use the word in everyday speech. Scientists define heat as thermal energy transferred between two systems at different temperatures that come in contact. Heat is written with the symbol q or Q, and it has units of Joules (\text JJJ).
Three melting ice cubes in a puddle of water on a mirrored surface.
Three melting ice cubes in a puddle of water on a mirrored surface.
Heat is transferred from the surroundings to the ice, causing the phase change from ice to water. Photo of ice cubes from flickr, CC BY 2.0.
Heat is sometimes called a process quantity, because it is defined in the context of a process by which energy can be transferred. We don't talk about a cup of coffee containing heat, but we can talk about the heat transferred from the cup of hot coffee to your hand. Heat is also an extensive property, so the change in temperature resulting from heat transferred to a system depends on how many molecules are in the system.
Relationship between heat and temperature
Heat and temperature are two different but closely related concepts. Note that they have different units: temperature typically has units of degrees Celsius (^\circ\text C
∘
Cdegree, C) or Kelvin (\text KKK), and heat has units of energy, Joules (\text JJJ). Temperature is a measure of the average kinetic energy of the atoms or molecules in the system. The water molecules in a cup of hot coffee have a higher average kinetic energy than the water molecules in a cup of iced tea, which also means they are moving at a higher velocity. Temperature is also an intensive property, which means that the temperature doesn't change no matter how much of a substance you have (as long as it is all at the same temperature!). This is why chemists can use the melting point to help identify a pure substance-−minusthe temperature at which it melts is a property of the substance with no dependence on the mass of a sample.
On an atomic level, the molecules in each object are constantly in motion and colliding with each other. Every time molecules collide, kinetic energy can be transferred. When the two systems are in contact, heat will be transferred through molecular collisions from the hotter system to the cooler system. The thermal energy will flow in that direction until the two objects are at the same temperature. When the two systems in contact are at the same temperature, we say they are in thermal equilibrium.
Zeroth law of thermodynamics: Defining thermal equilibrium
The zeroth law of thermodynamics defines thermal equilibrium within an isolated system. The zeroth law says when two objects at thermal equilibrium are in contact, there is no net heat transfer between the objects; therefore, they are the same temperature. Another way to state the zeroth law is to say that if two objects are both separately in thermal equilibrium with a third object, then they are in thermal equilibrium with each other.
∘
.