1 / 11

Chapter 5.1-5.3

Chapter 5.1-5.3. Thermochemistry. Thermochemistry. Thermo means heat or energy Energy: Capacity of doing work Work: Force x displacement. Types of Energy. Kinetic Energy (KE) Energy due to motion E k = ½ mv 2 Where m = mass & v = velocity. Types of Energy.

latifah-jensen
Télécharger la présentation

Chapter 5.1-5.3

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 5.1-5.3 Thermochemistry

  2. Thermochemistry • Thermo means heat or energy • Energy: Capacity of doing work • Work: Force x displacement

  3. Types of Energy • Kinetic Energy (KE) • Energy due to motion • Ek = ½ mv2 • Where m = mass & v = velocity

  4. Types of Energy • Potential energy (PE) • Energy due to position Gravity higher PE lower PE • Units: Calorie (cal), Joule (J) • 1 Cal = 4.184 J

  5. System • Where we focus our attention • Surroundings • Everything else

  6. First Law of Thermodynamics • Energy is conserved Piston pushed up & work (W) done by the gas (say 6 J) 10 J added (q)

  7. First Law of Thermodynamics • What happens to the difference (10 – 6)? • Retained inside. (causes Internal energy change, ΔE): 10 = 4 + 6 q (Heat applied) = ? q = ΔE + W (first law Thermodynamics) or ΔE = q-W (here -W, Work done by the gas) • ΔE = q +W (here +W, Work done on the gas) • Note: Two different sign conventions exist

  8. Enthalpy (H) ΔE = q-W (work done by a gas) q = ΔE + W q = ΔE + P ΔV ΔH = ΔE + P ΔV (constant pressure) H = E + PV

  9. Enthalpy or heat Content (H) Begin End 2H2 + O2 2H2O Say 484 kJ 1 kJ • Note: 484 kJ is the Heat content of the reactants (HR) and 1 kJ is the heat content of the products (HP).

  10. Enthalpy or heat Content (H) ΔH = Hp –HR = 1 – 484 = -483 kJ (exothermic) • Here, initial heat content> Final heat cont. • What happens to the difference? • It is given off.

  11. Enthalpy or heat Content (H) 2H2O  2H2 + O2 1 kJ (HR) 484 kJ (HP) Is heat absorbed or given off? Heat is absorbed ΔH = Hp –HR = 484 – 1 = 483 kJ (endothermic) • Here, initial heat cont < Final heat cont

More Related