Chapter 8: Gases Units of Pressure PDF

Chapter 8: Gases Units of Pressure Book Title: Chemistry: An Atoms First Approach Printed By: Deysi Santana Fuentes ([email protected]) © 2019 Cengage Learning, Cengage Learning Units of Pressure Because instruments used for measuring pressure, such as the manometer (a device for measuring the press...

Chapter 8: Gases Units of Pressure Book Title: Chemistry: An Atoms First Approach Printed By: Deysi Santana Fuentes ([email protected]) © 2019 Cengage Learning, Cengage Learning Units of Pressure Because instruments used for measuring pressure, such as the manometer (a device for measuring the pressure of a gas in a container.) (Fig. 8.3), often contain mercury, the most commonly used units for pressure are based on the height of the mercury column (in millimeters) that the gas pressure can support. The unit mm Hg ( a unit of pressure, also called a torr, standard atmosphere.) (millimeter of mercury) is often called the torr (another name for millimeter of mercury .) in honor of Torricelli. The terms torr and mm Hg are used interchangeably by chemists. A related unit for pressure is the standard atmosphere (a unit of pressure equal to .) (abbreviated atm): However, since pressure is defined as force per unit area, the fundamental units of pressure involve units of force divided by units of area. In the SI system, the unit of force is the newton (N) and the unit of area is meters squared . (For a review of the SI system, see the Review Chapter.) Thus the unit of pressure in the SI system is newtons per meter squared and is called the pascal (the SI unit of pressure; equal to newtons per meter squared.) (Pa). In terms of pascals, the standard atmosphere is Thus atmosphere is about pascals. Since the pascal is so small, and since it is not commonly used in the United States, we will use it sparingly in this book. However, converting from torrs or atmospheres to pascals is straightforward, as shown in Example 8.1. Figure 8.3 A simple manometer, a device for measuring the pressure of a gas in a container. The pressure of the gas is given by torr (equivalent to mm Hg). (a) (the difference in mercury levels) in units of . (b) . Interactive Example 8.1 Pressure Conversions The pressure of a gas is measured as atmospheres and pascals. torr. Represent this pressure in both Solution See Exercises 8.37 and 8.38 Chapter 8: Gases Units of Pressure Book Title: Chemistry: An Atoms First Approach Printed By: Deysi Santana Fuentes ([email protected]) © 2019 Cengage Learning, Cengage Learning © 2023 Cengage Learning Inc. All rights reserved. No part of this work may by reproduced or used in any form or by any means graphic, electronic, or mechanical, or in any other manner - without the written permission of the copyright holder.