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Questions and Answers
What is the process of a substance changing from a solid to a gas?
What is the process of a substance changing from a solid to a gas?
The Celsius scale is an absolute temperature scale.
The Celsius scale is an absolute temperature scale.
False
What is the unit of heat commonly used in chemistry?
What is the unit of heat commonly used in chemistry?
Joules (J)
Heat is transferred through ________________ waves in the process of radiation.
Heat is transferred through ________________ waves in the process of radiation.
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What is the term for the amount of heat required to change the temperature of 1 kg of a substance by 1°C?
What is the term for the amount of heat required to change the temperature of 1 kg of a substance by 1°C?
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Match the following types of heat transfer with their descriptions:
Match the following types of heat transfer with their descriptions:
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Heat always flows from a lower temperature to a higher temperature.
Heat always flows from a lower temperature to a higher temperature.
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What is the term for the process of a substance changing from a liquid to a solid?
What is the term for the process of a substance changing from a liquid to a solid?
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Study Notes
Heat
Change of State
- Occurs when a substance absorbs or releases energy, resulting in a change from one state (solid, liquid, gas) to another
- Types of change of state:
- Melting: solid to liquid
- Freezing: liquid to solid
- Evaporation: liquid to gas
- Condensation: gas to liquid
- Sublimation: solid to gas (e.g., dry ice)
- Deposition: gas to solid (e.g., frost)
Temperature Measurement
- Temperature scales:
- Celsius (°C): water freezes at 0°C, boils at 100°C
- Fahrenheit (°F): water freezes at 32°F, boils at 212°F
- Kelvin (K): absolute temperature scale, 0 K = -273.15°C
- Temperature measurement devices:
- Thermometers (mercury, digital, infrared)
- Thermocouples
- Resistance temperature detectors (RTDs)
Heat Transfer
- Methods of heat transfer:
- Conduction: direct contact between particles
- Example: metal spoon in hot soup
- Convection: movement of fluids ( liquids or gases)
- Example: heating a room with a radiator
- Radiation: electromagnetic waves
- Example: heat from the sun
- Conduction: direct contact between particles
- Heat transfer processes:
- Heat conduction: heat flows from higher to lower temperature
- Heat convection: heat flows with the movement of fluids
- Heat radiation: heat flows through electromagnetic waves
Heat
- Definition: energy transferred from one body to another due to a temperature difference
- Units of heat:
- Joules (J)
- Calories (cal)
- British thermal units (BTU)
- Heat capacity:
- Specific heat capacity: amount of heat required to change the temperature of 1 kg of a substance by 1°C
- Molar heat capacity: amount of heat required to change the temperature of 1 mole of a substance by 1°C
Heat
Change of State
- A substance changes state when it absorbs or releases energy, resulting in a phase transition (solid, liquid, gas)
- Melting occurs when a solid absorbs energy and becomes a liquid
- Freezing occurs when a liquid releases energy and becomes a solid
- Evaporation occurs when a liquid absorbs energy and becomes a gas
- Condensation occurs when a gas releases energy and becomes a liquid
- Sublimation occurs when a solid changes directly to a gas, e.g., dry ice
- Deposition occurs when a gas changes directly to a solid, e.g., frost
Temperature Measurement
- Celsius scale: water freezes at 0°C, boils at 100°C
- Fahrenheit scale: water freezes at 32°F, boils at 212°F
- Kelvin scale: absolute temperature scale, 0 K = -273.15°C
- Thermometers measure temperature using mercury, digital, or infrared technology
- Thermocouples measure temperature using the Seebeck effect
- Resistance temperature detectors (RTDs) measure temperature using changes in electrical resistance
Heat Transfer
- Conduction occurs when heat is transferred between particles in direct contact
- Convection occurs when heat is transferred through the movement of fluids (liquids or gases)
- Radiation occurs when heat is transferred through electromagnetic waves
- Heat always flows from higher to lower temperature
- Conduction is the primary method of heat transfer in solids
- Convection is the primary method of heat transfer in fluids
- Radiation is the primary method of heat transfer in gases
Heat
- Heat is the energy transferred from one body to another due to a temperature difference
- Joules (J) are the SI unit of heat
- Calories (cal) are a unit of heat, often used in nutrition and dietetics
- British thermal units (BTU) are a unit of heat, often used in engineering and HVAC
- Heat capacity is the amount of heat required to change the temperature of a substance
- Specific heat capacity is the heat capacity per unit mass of a substance
- Molar heat capacity is the heat capacity per mole of a substance
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Description
Learn about the different types of changes of state, such as melting, freezing, and evaporation, and understand how to measure temperature using Celsius and Fahrenheit scales.
