• Share
  • Email
  • Embed
  • Like
  • Save
  • Private Content
Chapter 17 thermochemistry sections 17.3 & 17.4
 

Chapter 17 thermochemistry sections 17.3 & 17.4

on

  • 1,869 views

 

Statistics

Views

Total Views
1,869
Views on SlideShare
1,862
Embed Views
7

Actions

Likes
1
Downloads
10
Comments
0

2 Embeds 7

http://chemistryreview2012.blogspot.com 6
http://www.blogger.com 1

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    Chapter 17 thermochemistry sections 17.3 & 17.4 Chapter 17 thermochemistry sections 17.3 & 17.4 Presentation Transcript

    • Chapter 17Honors ChemistryThermochemistry Copyright©2000 by Houghton 1 Mifflin Company. All rights reserved.
    • . Section 17.3Heat in Changes of State Copyright©2000 by Houghton 2 Mifflin Company. All rights reserved.
    • Heats of Fusion and Solidification How does the quantity of heat absorbed by a melting solid compare to the quantity of heatreleased when the liquid solidifies? Copyright©2000 by Houghton 3 Mifflin Company. All rights reserved.
    • The molar heat of fusion (∆Hfus) is the heat absorbed by one moleof a solid substance as it melts to a liquid at a constant temp. Copyright©2000 by Houghton 4 Mifflin Company. All rights reserved.
    • The molar heat of solidification(∆Hsolid) is the heat lost when one mole of a liquid solidifies at a constant temperature. Copyright©2000 by Houghton 5 Mifflin Company. All rights reserved.
    • That is,∆Hfus = –∆Hsolid. Copyright©2000 by Houghton 6 Mifflin Company. All rights reserved.
    • 17.4
    • 17.4
    • The amount of heat necessary tovaporize one mole of a given liquid is called its molar heat of vaporization (∆Hvap). Copyright©2000 by Houghton 10 Mifflin Company. All rights reserved.
    • The amount of heat released when 1 mol of vapor condenses at the normal boiling point is called its molar heat of condensation (∆Hcond). Copyright©2000 by Houghton 11 Mifflin Company. All rights reserved.
    • That is,∆Hvap = –∆Hcond. Copyright©2000 by Houghton 12 Mifflin Company. All rights reserved.
    • 17 Heats of Vaporization and Condensation.3
    • –Observe the phase changes as ice is converted to steam when heat is added.
    • 17.3
    • 17.5
    • 17.5
    • Section 17.4 Hess’s Law Reactants Products The change in enthalpy is the same whether the reaction takes place in one step or a series of steps.The change in enthalpy, Δ H, is independent of pathway. Copyright©2000 by Houghton 18 Mifflin Company. All rights reserved.
    • Figure 6.7 The Principle of Hess’s LawIt does not matter if H for a reactionis calculated in one step or a series ofsteps. Copyright©2000 by Houghton 19 Mifflin Company. All rights reserved.
    • The Principle of Hess’s Law Copyright©2000 by Houghton 20 Mifflin Company. All rights reserved.
    • Strategy for using Hess’s Law• Manipulate equations so that they add up to the desired equation. Copyright©2000 by Houghton 21 Mifflin Company. All rights reserved.
    • Calculations via Hess’s Law1. If a reaction is reversed, H is also reversed. N2(g) + O2(g) 2NO(g) H = 180 kJ 2NO(g) N2(g) + O2(g) H = 180 kJ2. If the coefficients of a reaction are multiplied by an integer, H is multiplied by that same integer. 6NO(g) 3N2(g) + 3O2(g) H = 540 kJ Copyright©2000 by Houghton 22 Mifflin Company. All rights reserved.
    • 3. Focus on the reactants and productsof the required reaction.Let’s do some Practice Problems Copyright©2000 by Houghton 23 Mifflin Company. All rights reserved.
    • Section 17.4 Standard Enthalpies of Formation• Hf • Change in enthalpy that accompanies the formation of one mole of compound from its elements with all substances in their standard states. Copyright©2000 by Houghton 24 Mifflin Company. All rights reserved.
    • A degree symbol on a thermodynamicfunction example Hsays that the process was carried outunder standard conditions. Copyright©2000 by Houghton 25 Mifflin Company. All rights reserved.
    • Standard StatesCompound For a gas, pressure is exactly 1 atmosphere. For a solution, concentration is exactly 1 molar. Pure substance (liquid or solid), it is the pure liquid or solid.Element The form [N2(g), K(s)] in which it exists at 1 atm and 25°C. Copyright©2000 by Houghton 26 Mifflin Company. All rights reserved.
    • Change in EnthalpyImportant!!!!!--------Enthalpies of many reactions can be calculated from enthalpies of formation of reactants and products. Hrxn° = np Hf (products) nr Hf (reactants) Copyright©2000 by Houghton 27 Mifflin Company. All rights reserved.
    • Hf for an element in its standard stateis Zero.Elements in their standard states are notincluded in the Hrxn calculations. Copyright©2000 by Houghton 28 Mifflin Company. All rights reserved.