1 / 7

Enthalpy

Enthalpy. In an exothermic reaction: e nergy flows out of the system . The flow of heat is negative (-) for the system. In an endothermic reaction: e nergy flows into the system . The flow of heat is positive (+) for the system. Enthalpy.

aizza
Download Presentation

Enthalpy

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. Enthalpy In an exothermic reaction: energy flows out of the system. The flow of heat is negative (-) for the system. In an endothermic reaction: energy flows into the system. The flow of heat is positive (+) for the system.

  2. Enthalpy Chemists like to know exactly how much energy is produced or absorbed by a given reaction. To make that process more convenient, the special energy function, enthalpy, was invented..

  3. Enthalpy Enthalpy is designated by H. The change in enthalpy (ΔH) for a reaction is equal to the energy that flows as heat. That is (ΔH) = heat

  4. Problem When 1 mol of sulfur dioxide reacts with excess oxygen to form sulfur trioxide, 198.2 kJ of energy is released as heat. Calculate ΔH for a process in which a 12.8g sample of sulfur dioxide reacts with excess oxygen. ΔH = -198.2 kJ/mol SO2 12.8g sample of SO2 (molar mass = 64.07g) is burned

  5. Problem When 1 mol of sulfur dioxide reacts with excess oxygen to form sulfur trioxide, 198.2 kJ of energy is released as heat. Calculate ΔH for a process in which a 12.8g sample of sulfur dioxide reacts with excess oxygen. 12.8g SO2 x 1 mol SO2/64.07g SO2 = 0.200 mol SO2 and 0.200 mol SO2 x -198.2kJ/molSO2 = -39.6kJ = ΔH

  6. Problem When 1 mol of hydrogen gas reacts with excess oxygen to form water, 241.8 kJ of energy is released as heat. Calculate ΔH for a process in which a 15.0g sample of hydrogen gas reacts with excess oxygen. ΔH = -241.8 kJ/mol H2 15.0g sample of H2 (molar mass = 2.016g) is burned

  7. Problem When 1 mol of hydrogen gas reacts with excess oxygen to form water, 241.8 kJ of energy is released as heat. Calculate ΔH for a process in which a 15.0g sample of hydrogen gas reacts with excess oxygen. 15.0g H2 x 1 mol H2/2.016g H2 = 7.44 mol H2 and 7.44 mol H2 x 241.8kJ/molH2 = -1800kJ = ΔH

More Related