ENERGY IN REACTIONS.

ENTHALPY - In our model of enthalpy - we shall also call it POTENTIAL ENERGY - The stored energy due to position.  The potential energy of particles depends upon the position of the particles and the force between them - the attractions.  The KINETIC ENERGY of particles is reflected in their temperature. Click here to go to temperature.

Energy was introduced in IPS as we built a model of KINETIC ENERGY due to motion and POTENTIAL ENERGY due to position.  Click here for powerpoint - download to play the animations.  Go to the IPS page - view the Eureka videos.  Short 5 minute clips.

Again in chemistry - We pulled back the rubber band - doing work and transferring energy to stretch the rubberband.  The rubberband gained potential energy.  We let go of the rubber band and its potential was converted to kinetic energy and it flew across the hall.  We put a wad of paper in front of the stretched rubber band and the potential energy was transferred to the wad of paper doing work on the paper and it flew across the room.  Energy in the form of kinetice energy (motion) was transferred to stretch the rubber band - it gained PE (moved tonewposition with more stored energy).  Kinetic enrgy was transferred to the wad of paper - it gained KE (moved faster gained more motion  - KE).  Rework these ideas with the graphic organizer the blank and the key. The kinetic energy transferred to the surroundings can be measured as a heat transfer. Click here to go to heat transfer.

MODEL for ATTRACTIONS between particles - rubber band or spring.  Energy must be transferred IN to stretch the rubber band - just as energy must be transferred IN to break attractions between particles. The particles gain potential energy in these farther apart positions just as the rubber band gains PE. Just as when the rubber band is released to come back together energy is transferred OUT, energy is transferred out as attractions form between particles.  As attractions form the potential energy of the particles is converted to kinetic energy and transferred out, just like the PE of the rubberband is converted to KE and then transferred to the wad of paper.

Applied first in phase changes first.  click here

Additional applications.  The Thermite Reaction.  The Burning Nut.  The frozen wood.

website with enthalpy help

series of segments to help with energy in reactions

another website with helpful info and video