Chemistry 151

Energy

(from an elementary school perspective)

Types of Energy

Types of Energy

2012: Vibrational Energy Activity Asia’s Musical Extravaganza

•Students will learn the concepts of vibrations and sound energy by seeing how different materials vibrate, the noises they make, and the shape that the material makes when it is vibrating.

•Students will build a xylophone.

•Students will perform several activities to learn about the properties of static electricity.

2012

Units of Energy

SI unit: joule (J)

1 J ~ 1 heartbeat

Everyday unit: calorie (cal)

1 cal = energy to heat 1 g H2O by 1°C

Energy conversions

Examples of Energy Sources

2012: Energy Activity Insulation Race

•Students use different materials to make a insulating box for an ice cube.

•Students rank the various insulators and discuss the reasons for this trend.

•Students study the effect of salt on melting ice.

Light energy

•Light is a form of energy that travels through space like a wave and is characterized by its wavelength.

Light energy

•Light is a form of energy that travels through space like a wave and is characterized by its wavelength.

Oxidation-Reduction Reactions

•A type of chemical reaction involving transfer of electrons from one substance to another.

•Often release energy.

Substance that loses electrons is oxidized

Substance that gains electrons is reduced

Batteries

•A device that converts stored energy within bonds to electricity (a flow of electrons) through a redox reaction.

The anode is oxidized

The cathode is reduced

•Electrons flow from the anode to the cathode.

Overall balanced rxn: 2 Al + 3 Cu2+ 2 Al3+ + 3 Cu

Energy and chemical reactions

•Molecules must collide with a certain minimum energy (the energy of activation) to react.

Increasing Reaction Rates

Strategy 1: increase the temperature

Increasing Reaction Rates

Strategy 2: add a catalyst

Catalyst Demo

Increasing Reaction Rates

Strategy 3: increase concentration of reactants