1.1 P64Comp Handout 1, Temperature and Heat.pdf

P64Comp Handout 1: Temperature and Heat Review Summary 1. Heat and temperature are related but NOT the same concepts. Why are they not the same Concepts. a. The subjective perception of “hot” or “cold” is related to an object’s temperature. Thus, the common definition of temperature is it...

P64Comp Handout 1: Temperature and Heat Review Summary 1. Heat and temperature are related but NOT the same concepts. Why are they not the same Concepts. a. The subjective perception of “hot” or “cold” is related to an object’s temperature. Thus, the common definition of temperature is it is a measure of the “hotness” or “coldness” of an object. b. Temperature directly relates to properties of objects. In chemistry, objects with high temperature are found to have molecules with high kinetic energy and vice-versa. c. An object’s temperature is measured using a thermometer, which is dependent on the properties and behavior of matter during a temperature change 2. Heat, on the other hand, is a form of kinetic energy. a. Heat is energy transferred between objects of different temperatures. Heat is not temperature (NOT synonymous); heat is what flows when there is a temperature difference. b. Heat flows from an object of higher temperature to an object of lower temperature. c. Because heat is energy, the quantity of heat is expressed in Joules (J). 3. Because heat is energy transferred between objects of different temperatures, a. Heat will transfer from an object of high temperature to an object of low temperature b. Heat will not flow if the temperature of both objects are the same; this is called thermal equilibrium 4. The measurement of temperature is dependent on the behavior of matter during temperature changes. Temperature can be measured through: a. Changes in volume in solids and liquids b. Changes in pressure in gases c. Changes in resistivity 5. Temperature scales are temperature measurements based on properties of matter. The more common temperature scales are: a. Celsius temperature scale – This is also known as the centigrade scale, because it is based on the freezing point (00C) and boiling point (1000C) of water (all at standard atmospheric pressure) and has 100 degrees in between. b. Fahrenheit temperature scale – This scale is also based on the freezing point (320F) and boiling point (2120F) of water at standard atmospheric pressure. The Fahrenheit degree is 5/9ths of a degree in the Celsius scale.  c. Kelvin temperature scale – The Kelvin scale is based on the changes in pressure and consequently temperature of gases in fixed volume containers. By extrapolation from pressure – temperature graphs, the zero temperature (absolute zero or 0 K) is determined to be at −273.150 𝐶. The Kelvin scale is not degree-based and is thus written without the degree sign. 6. Matter expands when temperature is increased. This expansion can either be linear or volumetric. a. Linear expansion: ∆𝐿 = 𝛼𝐿0 ∆𝑇, where ΔL is the change in length, L0 is the original length, and ΔT is the change in temperature b. Volume expansion: ∆𝑉 = 𝛽𝑉0 ∆𝑇, where ΔV is the change in volume, V0 is the original volume, and ΔT is the change in temperature c. The coefficients of linear (α) and volume (β) expansion depend on the kind of material that experiences the temperature change. 7. Thermal conductors are materials that permit the transfer of heat while thermal insulators are materials that prevent the transfer of heat. 8. There are three main methods of heat transfer: a. Conduction – transfer of heat between two bodies in contact b. Convection – transfer of heat through the motion of a mass from one place to another (more commonly in liquids and gases, because of their ability to flow) c. Radiation – transfer of heat through electromagnetic radiation