TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies.

What is energy? The capacity to do work or to produce heat is called energy. • Energy has neither mass nor volume. • Energy is detected only because of its effects. TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies.

Units of energy • The SI unit of energy is the joule (J). A common non-SI unit of energy is the calorie. • One calorie (cal) is the quantity of heat that raises the temperature of 1 g of pure water by 1ºC. • Your STAAR formula chart has the conversion factors you will use in class.

1. Calculate How many joules of energy are in a donut that contains 200.0 Calories? TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies. Kinetic energy The energy an object has because of its motion is called kinetic energy. •The kinetic energy of any moving object depends on its mass and speed. 1 kinetic energy = mass ×speed 2 2 1 KE = mv 2 2

•In chemistry, the kinetic energy is reflected in the motion of the particles and the temperature of the system. TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies. Potential energy Energy that is stored as a result of position or shape is called potential energy. In chemistry: P E o n Intermolecular t e Chemical Forces e r Bonds n g (IMFs) t y i O a l H H

Hydrogen Bonds in water molecules TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies.

Chemical energy The Potential Energy stored in the chemical bonds of a substance is called chemical energy. •During a chemical reaction, a substance is transformed into another substance with a different amount of chemical energy. •Breaking covalent bonds requires energy •Forming covalent bonds releases energy TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies. Heat or Thermal Energy Heat, q, is energy that transfers because of a temperature difference between objects. • Heat flows spontaneously from a warmer object to a cooler object until the temperature of both objects is the same. • Adding or removing heat to/from an object produces a change in the kinetic energy of its particles . • This change in KE can produce a change in temperature, or… • This change in KE can be used to produce a phase change.

1. Describe An ice cube at 0ºC is dropped into a cup of water at 45ºC. Describe what happens to the ice and water in terms of heat flow. TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies.

Conservation of energy The law of conservation of energy states that energy is neither created nor destroyed. • During any process, the energy of the Universe remains unchanged. • If the energy of the system increases, the energy of the surroundings must decrease by the same amount. • If the energy of the system decreases, the energy of the surroundings must increase by the same amount.

Surroundings The Universe is System EVERYTHING together TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies.

Endothermic process Heat is absorbed from the surroundings in an endothermic process. TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies.

Exothermic process An exothermic process is one that releases heat to its surroundings. TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies. TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies.

A – Increase in KE produces an increase in temperature TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies.

B – Increase in KE overcomes attraction between molecules. T = constant TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies.

C – Increase in KE produces an increase in temperature TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies.

D – Increase in KE overcomes attraction between molecules T = constant TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies.

E – Increase in KE produces an increase in temperature TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies.

E – Decrease in KE produces a decrease in temperature TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies.

D – Decrease in KE allows molecules to slow so attraction can pull them together. T = Const. TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies.

C – Decrease in KE produces a decrease in temperature TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies.

B – Decrease in KE allows molecules to slow so attraction can pull them together. T = Const. TEKS 11A: Understand energy and its forms, including kinetic, potential, chemical, and thermal energies.

A – Decrease in KE produces a decrease in temperature