Reviewer for Thermo PDF

# Types of Thermometer - Liquid-in-Tube Thermometer - a tube of glass with mercury or alcohol inside which expands when heated and contracts when cooled. - Bimetallic Strip Thermometer - consists of two bonded metal strips which expand differently when heated causing it to bend. - Resistanc...

# Types of Thermometer - Liquid-in-Tube Thermometer - a tube of glass with mercury or alcohol inside which expands when heated and contracts when cooled. - Bimetallic Strip Thermometer - consists of two bonded metal strips which expand differently when heated causing it to bend. - Resistance Thermometer - based on the concept that electrical resistance of a coil changes with temperature. - Constant Volume Gas Thermometer - is a type of thermometer that measures temperature by measuring the pressure of a gas at a constant volume. # What scales are used to measure temperature? ## Three Common Temperature Scales - **Celsius Scale** - Anders Celsius (1742) - regarded as the founder of Swedish astronomy - the freezing point of water is 0°C - the boiling point of water is 100°C - commonly used throughout the world, especially scientific laboratories. - **Fahrenheit Scale** - Daniel Fahrenheit (1724) - German physicist - based his scale on a mixture of ice, water, and ammonium chloride (which he defined as 0 degrees) and the temperature of a healthy human (which he defined as 96 degrees). - part of the English system of measurement. - **Kelvin Scale** - William Thomson (1848) known as Lord Kelvin - Scottish-Irish physicist - based on the concept of absolute zero, which is the lowest possible temperature that matter can reach. - primarily used in scientific research - an absolute temperature scale ## What is the significance of deriving temperature scales? - Deriving temperature scales is essential for establishing a standardized and reliable framework for measuring and understanding temperature. - It provides a common language for scientists, engineers, and everyday people to communicate about heat and cold. ## Temperature Conversion Formulae | Scale | Formula | |----------------|----------------------| | Celsius (°C) | (°F-32) / 9 * 5 | | Fahrenheit (°F) | (°C × 9 / 5) + 32 | | Kelvin (K) | °C + 273.15 | # Heat - Heat is a form of energy which produces sensation of warmth and the transfer of energy from a hot object to a colder object. - Surroundings: The flow of thermal energy from a high-temperature location to a low-temperature location. ## Thermal Expansion - Thermal expansion refers to the increase or decrease in every dimension of an object due to a temperature change. Most materials expand when heated and contract when cooled. - The amount an object expands can be calculated for both one-dimensional (linear) and three-dimensional (volumetric) expansion. # Coefficient of Expansion - Is a fundamental property of a material that quantifies how much its length changes per unit temperature change/ - Tells us how much a material will expand or contract when it gets hotter or colder. - The amount a material expands is characterized by the material's coefficient of expansion. ## Types of Thermal Expansion - **Linear Expansion** refers to the change in the length of a body or solid object when the temperature changes. This increase in length is proportional to the original length of the object and the temperature change. - **Volume Expansion** is the increase in the volume of a solid, liquid, or gas when it is heated. Similar to linear expansion, this increase is proportional to the original volume and the temperature change. ## Thermal Expansion Formula Formula: ΔL = (L₀) (α) (T₁ - T₀) Where: - ΔL = change in length (L - L₀) - L₀ = original length - α = coefficient of thermal linear expansion. Unit: 1/C° - T₁ = final temp. - T₀ = Initial or reference temp. - ΔT = change in temp. ### Simplified Formula: ΔL = L₀αΔT ### Final Length: L = L₀ + ΔL ## Volume Expansion Formula Formula: ΔV = (V₀) (β) (T₁ - T₀) Where: - ΔV = change in volume (V - V₀) - V₀ = original volume - β = coefficient of volumetric expansion. Unit: 1/C° - T₁ = final temp. - T₀ = Initial or reference temp. - ΔT = change in temp. ### Simplified Formula: ΔV = V₀βΔT ### Final Volume: V = V₀ + ΔV ## Heat & Internal Energy - Specific Heat Capacity - The greater the specific heat of a substance, the greater the amount of heat necessary to raise the temperature per unit mass. # Conclusion - The greater the specific heat of a substance, the greater the amount of heat necessary to raise the temperature per unit mass. # What can you see? ## Latent Heat - Latent heat is the amount of heat needed to change the phase of a given mass of a substance. - The heat associated with a phase change is called latent heat. - Latent means "hidden". - Latent heat is sometimes called hidden heat because it is not reflected by a temperature change. ## Latent Heat of Fusion - Is the amount of heat needed to change the phase of a unit mass of a substance from solid to liquid or liquid to solid. ## Latent Heat of Vaporization - Is the amount of heat needed to change the phase of a unit mass of a substance from liquid to gas or gas to liquid. # Three Methods of Heat Transfer - **Conduction** - The transfer of heat by the movement of a substance, or mass, from one place to another. The movement of heated air or water is an example. Many homes are heated by convection. - **Radiation** - The process of transferring energy by means of electromagnetic waves. Electromagnetic waves carry energy and can travel through a vacuum. These waves include visible light, infrared, and ultraviolet radiations. - **Convection** - A body that is a good absorber is also a good emitter of radiation. A good reflector is a poor absorber. An ideal radiator, which is also an ideal emitter, is called a blackbody. The continuous-spectrum radiation it emits is called blackbody radiation. ## Emissivity - A dimensionless number between 0 and 1 that represents the ratio of the rate of radiation from a particular surface to the rate of radiation from an equal area of an ideal radiating surface at the same temperature. - An ideal radiator, emissivity equals 1; while for an ideal reflector, emissivity equals 0. # Additional Key Terms - **Newton's Law of Cooling** states that the rate of warming or cooling of an object is proportional to the temperature difference between the object and its surroundings. - **Bose-Einstein condensate** is the extreme cooling of atoms, a condensate is formed that has completely different properties from all other phases of matter. # Thermal Properties of Matter ## State Variables or State Coordinates - State variables or state coordinates such as pressure, volume, and temperature describe the conditions under which a system exists. - The relation of these is described using an equation of state. ## Temperature - Temperature is a measure of the average kinetic energy of the particles in a substance. - The hotness and coldness of a substance. ## Volume - Volume is a measure of the amount of space occupied by a three-dimensional object. - It's essentially a way to quantify how big or small something is in terms of its three-dimensional extent. ## Pressure - Pressure is a force applied over a unit area. - It is a measure of how much force is exerted over a particular surface. - Pressure is defined as the force per unit area, P = F/A. # Kinetic Theory of Gases - Describes a gas as consisting of molecules moving independently in all directions at high speeds; the higher the temperature, the higher the average speed. The molecules collide with one another and with the walls of the container. - The distance between molecules is, on average, large compared to the size of the molecules themselves. ## Ideal Gas - Theoretically, an ideal gas (or perfect gas) is one in which the molecules are point particles (have no size at all) and interact only by collision. - Ideal gases are a theoretical concept that assumes gases behave in a perfectly predictable manner. - Real gases, on the other hand, deviate from ideal behavior, especially under extreme conditions (high pressure, low temperature, or high density). ## Pressure and Volume - If the number of molecules and the Kelvin temperature (N and T) are held constant for a gas, then pressure and volume are found to be inversely proportional: p x 1/V - As the volume decreases, the molecules do not have so far to travel and have a smaller surface area to hit. - It is logical that they exert more pressure (more force per unit area) than they did before. This relationship was recognized in 1662 by Robert Boyle (Chapter 11.2) and is called Boyle's law. ## Volume and Temperature - Volume and Temperature are directly proportional to each other. - If the volume and number of molecules (V and N) are held constant for a gas, pressure is directly proportional to the Kelvin temperature: p x T - As T increases, the molecules move faster and strike the container walls harder and more frequently. No wonder the pressure increases. ## Pressure and Number of Molecules - If the temperature and volume (T and V) are held constant for a gas, then pressure is directly proportional to the number of gas molecules present: p α N. - It is logical that the greater the number of molecules, the greater the number of collisions with the sides of the container. # Gas Laws ## Boyle's Law - At constant temperature and number of substance, the pressure is inversely proportional to volume. - Formula: P₁V₁ = P₂V₂