Presentation on theme: "Pressure and Temperature"— Presentation transcript:
1 Pressure and Temperature William Thomson“Lord Kelvin”
2 CA 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.
3 Measuring 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
4 An Early BarometerThe normal pressure due to the atmosphere at sea level can support a column of mercury that is 760 mm high.
5 Pressureis caused by the collisions of molecules with the walls of a containeris equal to force/unit areacan be measured using a variety of units
6 Pressure 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
7 Standard Pressure 760 torr 760 mm Hg (millimeters of mercury) 101.3 kPa (kilopascals)1 standard atmosphere (atm)
8 Converting 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
9 Converting 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
10 Converting 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
11 Air Pressure has many applications (in real life!) Here’s one of those applications !