Thermodynamics Flashcards
(41 cards)
What is temperature?
Temperature is the average kinetic energy of particles in a system.
Unit: Celsius or kelvin
What is heat?
Heat is the energy transferred between two systems at different temperatures.
Unit: Joules or Calorie (The quantity of heat needed to increase the temperature of 1 gram of water by 1 degree Celsius)
What is thermal equilibrium?
When two objects at different temperature, heat will flow from the hotter object to the cold object until a state of thermal equilibrium is reached where both objects have the same temperature.
What is thermal expansion?
Matter in general expands when it is heated even when there is no phase change. When volume increases, density decreases.
What is the relationship between bond energy and thermal expansion?
As bond energy increases, thermal expansion decreases.
Explanation: Substances with higher bond energies (which often correspond to higher melting points) have atoms that are more tightly held together. When heated, these atoms vibrate more but are less able to move apart due to the stronger interatomic forces. Therefore, materials with higher bond energies tend to expand less upon heating compared to substances with weaker bonds.
How does thermal expansion compare among solids, liquids, and gases when heated? Which state of matter best retains its shape?
• Gases expand the most when heated, followed by liquids, then solids (which expand the least).
• Solids are best at keeping their original shape due to strong intermolecular forces.
Ways of heat propagation
- Conduction
- Convection
- Radiation
What is heat(thermal) capacity?
Heat capacity is the amount of heat energy required to raise 1 degree Celsius of a substance.
What is specific heat capacity?
Specific heat capacity is the amount of heat energy required to raise 1 degree Celsius / 1 Kelvin in 1 gram/ 1kg of that substance.
What is the formula used to calculate the amount of heat gained or lost?
Phase change from gas to plasma
Ionization
Phase change from plasma to gas
Recombination
Does temperature increase during a phase change? Explain your answer.
No, temperature does not increase during a phase change because temperature is the average kinetic energy of the particles in a system. During a phase change, the heat energy is used to break the intermolecular forces (or bonds) between particles, rather than increasing their kinetic energy.
Is heat the same as kinetic energy?
❌ No. Heat is the energy transferred between systems due to temperature difference. Kinetic energy is the energy of motion of particles, which contributes to temperature.
Is heat the same as temperature?
False.
Heat is the energy transferred between two systems.
Temperature is the average kinetic energy of a system.
True or False? Phase changes cannot occur with changes in heat energy.
❌ False.
When heat is added to or removed from a system (change in heat energy), it causes a phase change by breaking or forming intermolecular bonds. Although the kinetic energy (and temperature) stays the same during the phase change, a change in heat energy is essential for the process to occur.
What is latent heat of fusion?
The amount of heat energy required to change 1g of solid to a liquid with no temperature change
What is latent heat of vaporization?
It is the amount of heat energy required to turn 1g of liquid to a gas without no temperature change.
Latent heat of fusion/ vaporization formula
What is internal energy?
The internal energy (U) is the combination of all kinetic energy and potential energy of a system.
What is kinetic energy in a thermodynamic system?
Kinetic energy is the energy of motion of particles in a system. It reflects how fast the particles are moving and is directly related to temperature.
What is potential energy in a thermodynamic system?
Potential energy is the energy related to the positions and spacing of particles in a system. It increases when particles are moved farther apart and intermolecular forces are weakened, such as during melting or vaporization.
What is internal energy in a system?
Internal energy is the total energy of a system, made up of kinetic energy (from particle motion) and potential energy (from intermolecular forces).
What happens when heat energy is added to a system?
When heat is added, it increases the system’s internal energy, which can either raise the kinetic energy (increasing temperature) or the potential energy (causing a phase change), but not both at the same time.
