Presentation on theme: "Pressure and Temperature"— Presentation transcript:
1Pressure and Temperature William Thomson“Lord Kelvin”
2CA StandardsStudents know the values and meanings of standard temperature and pressure (STP).Students know how to convert between the Celsius and Kelvin temperature scales.Students know there is no temperature lower than 0 Kelvin.
3Measuring Pressure The first device for measuring atmospheric pressure was developed by Evangelista Torricelliduring the 17th century.The device was called a “barometer”Baro = weightMeter = measure
4An Early BarometerThe normal pressure due to the atmosphere at sea level can support a column of mercury that is 760 mm high.
5Pressureis caused by the collisions of molecules with the walls of a containeris equal to force/unit areacan be measured using a variety of units
6Pressure Pressure is the force created by the collisions of molecules with the walls of a containerUnitSymbolDefinition/RelationshipMillimeter of mercurymm HgPressure that supports a 1 mm column of mercury in a barometerTorrtorr1 torr = 1 mm HgPascalPaSI pressure unit1 Pa = 1 newton/meter2AtmosphereatmAverage atmospheric pressure at sea level and 0 C
7Standard Pressure 760 torr 760 mm Hg (millimeters of mercury) 101.3 kPa (kilopascals)1 standard atmosphere (atm)
8Converting Pressure Units Gas law problems involving pressure require that the pressure be in the SAME UNITS!1 atm = kPa = 760 mm HgConverting kPas to atmsx atms = ____ kPas1atm kPaConverting kPas to mm Hgx mm Hg = ____ kPas760 mm Hg kPa
9Converting Pressure Units 1 atm = kPa = 760 mm HgA gas sample has a pressure of mmHg. What is the pressure of this gas sample in atmospheres and in kilopascals?Converting mm Hg to atmsx atms = 800 mm Hg1atm mm HgConverting mm Hg to kPasx kPas = 800 mm Hg101.3 kPa 760 mm Hgx = atmx = kPa
10Converting Pressure Units 1 atm = kPa = 760 mm HgA tank of oxygen is under a pressure of about 4.00 x 103 kPa. Express this pressure in millimeters of mercury.Converting kPas to mm Hgx mm Hg = 4 x 103 kPas760 mm Hg kPax = 3.00 x 104 mm Hg
11Air Pressure has many applications (in real life!) Here’s one of those applications !