12+Measuring+of+Temperature


 * Measuring of Temperature **
 * Measuring [[image:http://symphony.lotus.com/software/lotus/symphony/servlet/JiveServlet/download/21-2290-3575-1082/thermometer%20hot.gif width="217" height="411" align="right" link="http://symphony.lotus.com/software/lotus/symphony/servlet/JiveServlet/download/21-2290-3575-1082/thermometer%20hot.gif"]] **
 * Temperature is the quantity that tells how warm or cold an object is with respect to some standard. It is the average kinetic energy per molecule in the object.
 * A thermometer is a common tool for measuring temperature. It uses expansion and contraction of a liquid to show a change in temperature. When the surroundings are colder than the liquid, the liquid contracts and goes down, showing a lower number. When the surroundings are hotter than the liquid, the liquid expands and goes up, showing a higher number. The surroundings expand and contract the liquid because it tries and reach equilibrium with the thermometer, either adding kinetic energy or taking kinetic energy away. When it reaches equilibrium, the liquid inside the thermometer stops moving and shows you the temperature.
 * Scales **
 * There are three scales for measuring temperature:

//Fahrenheit (ºF)// -457º is absolute zero, 32º is freezing point for water, 212º for boiling point for water

//Celsius (ºC)// -273.15º is absolute zero, 0º is freezing point for water, 100º is boiling point for water

//Kelvin (K)// 0 K is absolute zero, 273 K is freezing point for water, 373 K is boiling point for water


 * To change from Fahrenheit to Celsius, you use the equation //º//C = 5/9 (//º//F - 32). To change from Celsius to Fahrenheit, you use the equation //º//F = 9/5 //º//C + 32. To change from Celsius to Kelvin, you use the equation K = //º//C + 273.15.


 * [[image:http://content.answers.com/main/content/wp/en-commons/thumb/d/d1/340px-Phase_change_-pn.png align="left" link="http://content.answers.com/main/content/wp/en-commons/thumb/d/d1/340px-Phase_change_-pn.png"]]Phase Changes **
 * When in the solid phase, molecules in a substance have very small movements (vibrations). The object has a definite shape and volume.
 * When in the liquid phase, molecules in a substance have bigger movements (vibrations) and can slip past each other. The object has a definite volume but no definite shape.
 * When in the gaseous phase, molecules in the substance have even bigger movements (vibrations). The object does not have a definite shape or volume.
 * When in the plasma phase, the molecules break into ions and electrons.


 * In order to change phase, thermal energy is either added or taken away. When thermal energy is added, the molecules have more kinetic energy and vibrate more, allowing them to break free from the form. When thermal energy is taken away, the molecules have less kinetic energy and vibrate less, making them more rigid in form.


 * For water, when changing from its solid phase to its liquid phase (melting), the amount of thermal energy need is 80 calories per gram. When changing from the liquid phase to the gaseous phase (evaporation), 540 calories per gram are needed.
 * When changing water from the liquid phase to the gaseous phase (condensation) 540 calories of heat are released. When changing water from the liquid phase to solid phase (freezing), 80 calories of heat are released.

Note: Condensation is a //warming// process. Evaporation and boiling (evaporation beneath the surface of a liquid) are //cooling// processes.