Energy Changes
- Created by: Gaynor
- Created on: 20-03-18 15:31
View mindmap
- Energy Changes
- Exothermic and Endothermic Reactions
- An exothermic reaction is a reaction that transfers energy to the surroundings
- An endothermic reaction is one that takes in energy from the surroundings
- Hand warmers are exothermic
- Injury packs are endothermic
- In an exothermic reaction graph, the products are at a lower level then the reactants
- In an endothermic reaction graph, the products have a higher energy than the reactants
- Bond Energies
- Energy is released when new bonds are formed
- Bond formation is exothermic
- Energy must be supplied to break existing bonds
- Bond breaking is endothermic
- The overall energy change is the sum of the energies needed to break bonds in the reactants minus the energy released when bonds are formed in the products
- Energy is released when new bonds are formed
- Cells and Batteries
- An electrochemical cell is a system made up of two different electrodes in contact with an electrolyte
- If the electrodes are connected by a wire, a charge is able to flow and electricity is produced
- Non-rechargeable batteries contain cells which use irreversible reactions. Once one of the reactants is used up, they don't produce any more charge
- In a rechargeable battery, the reaction can be reversed by connecting it to an external electric current
- Fuel Cells
- A fuel cell is an electrical cell that's supplied with fuel and oxygen and uses energy from the reaction between them to produce electrical energy efficiently
- The electrolyte is often potassium hydroxide
- Hydrogen goes into the anode compartment and oxygen goes into the cathode compartment
- Hydrogen ions move to the cathode and oxygen moves to the anode
- Exothermic and Endothermic Reactions
Comments
No comments have yet been made