Chemistry - Exo or Endo
Exothermic and Endothermic
Endothermic
Exothermic
Heat exits the reaction. The surrounding temperature goes up
Heat exits the reaction. The temperature outside goes down
Energy Profiles
Breaking bonds involves putting energy into the reaction
Wen bonds are made energy is released
Reaction Energy Diagram shows the energy at the start of the reaction and at the end
Reaction Pathway along with the activation energy is plotted between the reactants and products
Energy Bond Calculations
Bonds Broken-Bonds Made = Energy Change
Cells and Batteries
In Non-rechargeable cells and batteries, the chemical reactions stop when one of the reactants has been used up. E.g Alkaline batteries
In rechargeable cells and batteries can be recharged because the chemical reactions are reversed when an external electrical current is supplied. Forcing the reaction the other way, therefore the electrons
Hydrogen Fuel Cells
At the Anode (positive), the Hydrogen oxides and produces Hydrogen ions. The electrons move along the circuit
At the Cathode (negative), the Oxygen reduces and gains the electrons creating the oxygen ions
The Hydrogen ions and Oxygen ions form an ionic bond to make water
4H+ + O2+4e-