thermal dynamics Flashcards
Specific heat capacity
Key:
- Often referred to as thermal capacity
- Different masses have different heat capacities
- 1 kg = 1 JOULES
- Q = mcΔT
When heated, some materials increased in temperature more quickly than others. The property of the material that describes this phenomenon is called the specific heat capacity and is defined as the amount of energy required to increase the temperature of 1 kg of the substance by 1 °C (or K).
Are Liquids and gasses good insulators or conductors?
Key
- far apart
liquids and gasses are usually poor conductors (Insulators) of heat. In gasses and liquids, the particles are far apart, making energy transfer by collision very inefficient.
Describe the key process that moves thermal energy around the Earth’s mantle?
Convection currents in the molten rock move hotter less dense rock outwards and cooler denser rockfalls.
What is temperature?
Key:
- Average kinetic energy
- Measurement
A temperature is a number that is related to the average kinetic energy of the molecules of a substance. Temperature is the measurement.
Kow the difference between temperature and heat;
Heat is the total amount of energy possessed by all the molecules in an object.
What is Celius?
Key:
- Scale
Celsius is a temperature scale. 0 degrees - 100 degrees. freezing point - boiling point.
What is kelvin?
Key:
- Scale
Kelvin is a temperature scale. - 273 kelvin - +273 Kelvin.
Absolute zero to evaporation
Conversion between Celcius and Kelvin
From Celcius to Kelvin = +273 Kelvin
From Kelvin to Celcius = -273 kelvin
What is heat?
- Motion of molecules
Heat energy is the result of the movement of tiny particles called atoms, molecules, or ions in solids, liquids, and gases. The motion of atoms and molecules creates a form of energy called heat or thermal energy which is present in all matter
Explain why faster atoms and molecules give off a hotter temperature.
Key:
- Kinetic energy
The faster a particle moves, the more kinetic energy it has. Kinetic energy is related to heat. The motion of atoms and molecules creates a form of energy called heat, The faster the particles in a substance move, the hotter it is.
What is the Kinetic theory of matter?
Key:
- Atoms and Molecules
- Viberate
- Space
Kinetic theory of matter: All matter is made up of atoms and molecules that are constantly moving. When heat is added to a substance, the molecules and atoms vibrate faster. As atoms vibrate faster, the space between atoms increases. ( Thermal expansion)
how do particles in solids interact?
Key:
- Viberate
- Potential energy
- Regular shape
Particles in solids are not moving but vibrating.
A lot of potential energy is stored in a strong force that holds the energy together. Solids are tightly packed, usually in a regular pattern.
How do particles in liquids interact?
Key:
- Kinetic energy
- Space
- Dense
The particles in a liquid have more kinetic energy than the particles in the corresponding solid. Because they are moving faster, the particles in the liquid occupy more space, and the liquid is less dense than the corresponding solid.
How do particles in gasses interact?
Key:
- No regular arrangement
Particles in a gas are well separated with no regular arrangement. Molecules are rasing.
What is absolute zero?
- lowest
- No heat energy
- Minimal vibrational
Absolute zero is the lowest possible temperature where nothing could be colder and no heat energy remains in a substance. Absolute zero is the point at which the fundamental particles of nature have minimal vibrational motion.
What is the zeroth Law?
Key:
- Equilibrium
- Second
- Size
Two bodies in contact will come to thermal equilibrium. The law defines temperature as a property independent of material. In that sense, the temperature does not depend on the size of the material (the number of molecules). However, smaller substances will reach their heat capacity faster.
It is the second law of thermodynamics.
What is the First Law?
Key:
- Delta U = Q - W
- Work
Based on the law of conservation of energy.
Delta U = Q - W
- The internal energy of a substance can increase if worked.
- The First Law of Thermodynamics states that energy is conserved and cannot be created or destroyed. If there is an energy change in a system, all the energy must be accounted for.
What is thermal Equilibrium?
Key:
- Two substances
- Same temperature
The condition under which two substances in physical contact with each other exchange no heat energy. Two substances in thermal equilibrium are said to be at the same temperature.
What is Internal energy?
Key:
- Random
- Microscope
Internal energy is defined as the energy associated with the random, disordered motion of molecules.
It refers to the invisible microscopic energy on the atomic and molecular scale
What is a thermometer?
Key:
- Thermo (heat) and meter (measuring device).
A thermometer is a tool that measures temperature — how hot or cold something is. Made up of thermo (heat) and meter (measuring device).
What is Thermal Expansion?
Key:
- Viberate
- Kinetic energy
- Average separation
Thermal expansion is the tendency of matter to change its shape, area, and volume in response to a change in temperature. When a substance is heated, the kinetic energy of its molecules increases. When the temperature is increased, the kinetic energy of atoms increases and the atoms vibrate and move, resulting in a greater average separation of atoms and thus thermal expansion
What is a Thermal Gradient?
Key:
- High to low
- Conservation temperature
A temperature gradient is a physical quantity that describes in which direction and at what rate the temperature changes the most rapidly around a particular location.
- Thermal energy flows from a High level to a lower level.
- The heat comes from a higher source.
What is Conduction?
Key:
- Solids are better conductors
- Metals make good conductors
- Vibration and collisions
- Transfer of energy without a change in the matter.
Conduction is the transfer of heat through a substance as a result of collisions between neighboring vibrating particles. This transfer of kinetic energy from particle to particle continues until thermal equilibrium is reached.
-In solids, the particles are more tightly bound and closer together than in liquids and gases.
Thus, kinetic energy can be transferred more quickly.
What is Convection?
Key:
- As it rises, it pulls cooler fluid down to replace it.
Moving particles transfer thermal energy through a fluid by forming convection currents. Convection currents move thermal energy through many fluids.
- As water’s temperature increases in the presence of a heat source, it will become less dense and rise. As it moves up and away from the heat source, it cools and becomes denser and sinks.
How can we Reduce convection currents?
Key:
- Remember that convection is not always negative as it distributes thermal energy
- Prevention of fluid movement – smaller rooms
- Trapping fluids – layers trapping air (insulation)
Air is a poor conductor and by trapping it between the panes, convection currents cannot be set up. Heat loss through walls can be reduced using cavity wall insulation.
What is Radiation?
Key:
- Radiation is a form of energy transport consisting of electromagnetic waves traveling at the speed of light.
Electromagnetic waves emitted by all objects. Radiation is a method of heat transfer that does not rely upon any contact between the heat source and the heated object.
Black body emitters
An object is considered a perfect black body when it absorbs all of the incoming light and does not reflect any. It appears perfectly black at room temperature.
It is an ideal emitter: at every frequency, it emits as much or more thermal radiative energy as any other body at the same temperature.
Explain the process of evaporation
Key:
-Evaporation is the process by which water changes from a liquid to a gas or vapor.
The molecules move and vibrate so quickly that they escape into the atmosphere as molecules of water vapor.
What is Latent Heat?
Key:
- Without change…
The heats required to convert a solid into a liquid or vapor, or a liquid into a vapor, without change of temperature.
Q = mcΔT explains this formula
Clue:
150 mL of water is heated from 10°C to 50°C. What amount of energy is required for this
temperature change to occur?
The quantity of energy, Q, transferred to or from a substance in order to change its temperature is directly proportional to three factors:
• The mass of the substance (m)
• The change in temperature (ΔT) in K
• The specific heat capacity of the substance (c). ( Can be found on a table)
Thus,
Q = mcΔT
ΔT = Q/MC explain this formula and how it is used.
clue:
A cup holds 250 mL of water at 20 ̊C. 10.5 kJ of heat energy is transferred to the water. What temperature does the water reach after the heat is transferred?
• The mass of the substance (m) • The change in temperature (ΔT) in K • The specific heat capacity of the substance (c). ( Can be found on a table) Thus, Temperature = ΔT = Q/MC
