1 / 15

Chapter 6 Gases

Chapter 6 Gases. 6.7d Volume and Moles (Avogadro’s Law). Avogadro's Law: Volume and Moles. In Avogadro’s Law the volume of a gas is directly related to the number of moles ( n ) of gas. T and P are constant. V 1 = V 2 n 1 n 2. Learning Check.

hogan
Télécharger la présentation

Chapter 6 Gases

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 6 Gases 6.7d Volume and Moles (Avogadro’s Law)

  2. Avogadro's Law: Volume and Moles In Avogadro’s Law • the volume of a gas is directly related to the number of moles (n) of gas. • T and P are constant. V1 = V2 n1n2

  3. Learning Check If 0.75 mole helium gas occupies a volume of 1.5 L, what volume will 1.2 moles helium occupy at the same temperature and pressure? 1) 0.94 L 2) 1.8 L 3) 2.4 L

  4. Solution 3) 2.4 L STEP 1 Conditions 1 Conditions 2 V1 = 1.5 L V2 = ??? n1 = 0.75 mole He n2 = 1.2 moles He STEP 2 Solve for unknown V2 V2 = V1 x n2 n1 STEP 3 Substitute values and solve for V2. V2 = 1.5 L x 1.2 moles He = 2.4 L 0.75 mole He

  5. STP The volumes of gases can be compared at STP, Standard Temperature and Pressure, when they have • the same temperature. Standard temperature (T) 0°C or 273 K • the same pressure. Standard pressure (P) 1 atm (760 mm Hg)

  6. Molar Volume At standard temperature and pressure (STP), 1 mole of a gas occupies a volume of 22.4 L, which is called its molar volume.

  7. Molar Volume as a Conversion Factor The molar volume at STP can be used to form conversion factors. 22.4 L and 1 mole 1 mole 22.4 L

  8. Using Molar Volume What is the volume occupied by 2.75 moles N2 gas at STP? The molar volume is used to convert moles to liters. 2.75 moles N2 x 22.4 L = 61.6 L 1 mole

  9. Guide to Using Molar Volume

  10. Learning Check A. What is the volume at STP of 4.00 g of CH4? 1) 5.60 L 2) 11.2 L 3) 44.8 L B. How many grams of He are present in 8.00 L of gas at STP? 1) 25.6 g 2) 0.357 g 3) 1.43 g

  11. Solution A. 1) 5.60 L 4.00 g CH4 x 1 mole CH4 x 22.4 L (STP) = 5.60 L 16.0 g CH4 1 mole CH4 B. 3) 1.43 g 8.00 L x 1 mole He x 4.00 g He = 1.43 g He 22.4 L 1 mole He

  12. Gases in Equations The volume or amount of a gas at STP in a chemical reaction can be calculated from • STP conditions. • mole factors from the balanced equation.

  13. STP and Gas Equations What volume (L) of O2 gas is needed to completely react with 15.0 g of aluminum at STP? 4 Al(s) + 3 O2 (g) 2 Al2O3(s) Plan: g Al mole Al mole O2 L O2 (STP) 15.0 g Al x 1 mole Al x 3 moles O2x 22.4 L (STP) 27.0 g Al 4 moles Al 1 mole O2 = 9.33 L O2 at STP

  14. Learning Check What mass of Fe will react with 5.50 L O2 atSTP? 4 Fe(s) + 3 O2(g) 2 Fe2O3(s)

  15. Solution 4Fe(s) + 3O2(g) 2Fe2O3(s) ? 5.50 L at STP 5.50 L O2 x 1 mole x 4 moles Fe x 55.9 g Fe = 18.3 g 22.4 L 3 moles O2 1 mole Fe

More Related