Energy Notes

Energy

Homework

• Chapter 17, Section 1: Problems 1-11
• Chapter 18, Section 1: Problems 1-6

Bell Ringer Questions

• What is energy?
• Give three examples of energy.
• What is the Earth's primary source of energy?

Concept Map and Graphing

• Concept Map: Relate Chemical, Mechanical, Light, Potential, Kinetic, Thermal, Electricity, Nuclear, Wind, and Sound energy types.

• Graph Components:

  • Title
  • Scaling (equal graduations)
  • Labels with units

• Data Representation: Create a graph with the provided time and temperature data. Understand what is happening between 180 and 300 seconds, interpret the observations.

  Time (s)	Temperature (°C)
  0	-10
  60	-6
  120	-3
  180	0
  240	0
  300	0
  360	10
  420	33
  480	67
  540	82
  600	100
  660	100
  720	120
  780	150

Hurricane Anatomy Bell Ringer

• Go to: https://spaceplace.nasa.gov/hurricanes/en/
• Questions:
  • What is the anatomy of a hurricane?
  • What does the hurricane use as its energy source?
  • Which paragraph helped you answer question number 2?
  • What is the most dangerous part of a hurricane?
    • Water (Flooding), Surge, Rain, Wind

Hurricane Anatomy

• Lifecycle:
  • Formation: Storms in a disturbed area of the ocean.
  • Tropical Depression: Thunderstorms start to swirl around a center.
  • Tropical Storm: Winds over 39 mph.
  • Hurricane: Winds over 74 mph.
  • Weakens After Making Landfall
• Inside:
  • Eye Wall: Dense clouds with the strongest winds.
  • Eye: Relatively calm, clear area approximately 20-40 miles across.
  • Outflow
• Saffir-Simpson Scale:
  • Category 1: Winds 74-95 mph, Surge 4-5 ft
  • Category 2: Winds 96-110 mph, Surge 6-8 ft
  • Category 3: Winds 111-130 mph, Surge 9-12 ft
  • Category 4: Winds 131-155 mph, Surge 13-18 ft
  • Category 5: Winds 155 mph-plus, Surge above 18 ft
• Hurricane Energy Source:
  • Warm air rises from the ocean.
• Components:
  • Surface winds
  • Rising warm air
  • Dense cloud shield
  • Rainbands: Thunderstorms ranging from a few miles to tens of miles wide and 50 to 300 miles long.

Hurricane Development

• Movement of heat between air and water.
• Movement of cool and warm air (Wind).
• Winds flow outward above the storm, allowing the air below to rise.
• Humid air rising makes the clouds of the storm.
• Light winds outside the hurricane steer it and let it grow.
• Warm ocean water (more than 80°F) provides energy for the hurricane and causes more evaporation, making humid air and clouds.

Bell Ringer

• What is energy?
• Where are the reactants and products located in a chemical equation?
• Which direction does heat flow?

Energy

• Ability to do work.
• Equation: $E=mc^2$
  • Energy is equal to mass times the speed of light squared.

Energy and Chemistry

• Exchange of energy.
• Change in particle movement.
  • Often shown as a change in the speed of particles.
• Indirect measurement of particle speed change: Temperature.
• Thermochemistry.

Energy in Chemical Reactions

• Example Reaction: $H<em>2 + O</em>2 \rightarrow H_2O$
  • Reactants: $H<em>2$, $O</em>2$
  • Products: $H_2O$

Energy Diagrams

• Reaction coordinate diagrams illustrating energy changes during a reaction.

Exothermic vs. Endothermic Reactions

• Exothermic Reaction:
  • Potential Energy: Reactants --> Products + Energy Released
• Endothermic Reaction:
  • Potential Energy: Reactants + Energy Absorbed --> Products

Thermometer Measurement

• Thermometers measure an increase in temperature during an exothermic reaction because they receive energy from the system.

Catalysts

• An element or compound that:
  • Speeds up a chemical reaction.
  • Lowers activation energy.
  • Is not consumed in the reaction.
• Energy can also be used.

Reaction Coordinate Diagram

• Diagram representing the energy changes during a chemical reaction.
• Letters to represent on the diagram:
  • W
  • U
  • T
  • X

Endothermic vs. Exothermic Reactions

• Difference between endothermic and exothermic reactions reflected on a reaction coordinate diagram.

Heat Flow

• Heat flows from warmer regions to cooler regions (where there is a lack of heat).

System and Surroundings

• Energy interaction between system and surroundings.

Types of Systems

• Open System:
  • Matter and energy can escape.
• Closed System:
  • Matter cannot escape, but energy can.
• Isolated System:
  • Matter and energy cannot escape.
• The Earth as a System: Discuss with evidence.

Forms of Energy

• Kinetic Energy: Energy of movement.
  • Thermal Energy: Energy of moving particles (heat).
  • Mechanical Energy: Energy of objects in motion.
  • Electrical Energy: Energy of particles moving through a wire.
  • Magnetic Energy: Energy causing push or pull.
  • Sound Energy: Form of energy we can hear.
• Potential Energy: Stored energy to be used later.
  • Light Energy: Form of energy our eyes can detect.
  • Chemical Energy: Energy stored in food, fuel.
  • Elastic Energy: Energy stored in objects that are stretched.
  • Nuclear Energy: Energy stored in the center of particles.
  • Gravitational Energy: Energy stored in an object above the Earth's surface.

Energy Transfer and Conservation

• Eating food stores chemical energy (form of potential energy).
• Walking uses mechanical energy (form of kinetic energy).
• Energy is always being transferred and is conserved.
• Understanding the direction of energy flow is important.

Exit Ticket Questions

• What is energy?
• How is energy related to chemistry?
• What is a reaction coordinate?
• What is an endothermic reaction?
• How is that different from an exothermic reaction?
• What is a catalyst?
• What is activation energy of a chemical reaction?
• How does a catalyst impact the activation energy of a chemical reaction?

Additional Exit Ticket Questions

• What is energy?
• How is energy like a wave and a particle?
• What is the difference between a microwave and a gamma ray?
• How is energy related to chemistry?
• What is a reaction coordinate?
• What is a catalyst?
• What is activation energy of a chemical reaction?
• How does a catalyst impact the activation energy of a chemical reaction?

Bell Ringer Experiment

• Reaction: Barium Hydroxide (Ba(OH)2) + Ammonium Chloride (NH4Cl)
• Procedure:
  1. Take two scoops of $Ba(OH)_2$ and add it to the test tube.
  2. Insert thermometer and record the temperature.
  3. Add one scoop of $NH_4Cl$ to the test tube.
  4. Record the temperature.
  5. Write any other observations
• Task:
  • Decide whether the reaction is endothermic or exothermic and use data to support your claim.
  • Draw your setup before and after showing the flow of heat.
  • Draw and label a reaction coordinate diagram to show the change in energy.

Bell Ringer: Wave Structure

• What is the structure of a wave?
• What is frequency and what are the units for frequency?
• What is wavelength and what are the units for wavelength?

Energy: Wave-Particle Duality

• Energy shows properties of both waves and particles.

Energy as Waves

• Electromagnetic Spectrum: Radio waves, Microwaves, Infrared, Visible Light, Ultraviolet, X-rays, Gamma rays.
• Visible Light Spectrum: 700nm (Red) to 400nm (Violet)
• Wavelength: Longer to Shorter

Wave Properties

• Wavelength ($\lambda$):
  • Length of wave or vibration.
  • Typically in nanometers (nm).
  • $1 nm = 1 x 10^{-9} m$
• Frequency ($v$):
  • How often one wave crosses a point or how often the vibrations occur.
  • In inverse seconds ($s^{-1}$) or Hertz (Hz).
• Amplitude (A):
  • Distance from center line.
  • Shows amount of energy contained.
  • Unit depends on wave (e.g., Decibel).

Wave Equations

• $c = \lambda v$
  • $c$ = speed of light
  • $\lambda$ = wavelength (m or nanometers)
  • $v$ = frequency
• Speed of light: $c = 3.0 x 10^8 m/s$
• $E = hv$
  • E = energy
  • h = Planck's constant ($6.626 x 10^{-34} Js$)
  • $v$ = frequency

Example Problems

1. What is the frequency of a wave with a wavelength of 730 nm?
2. What is the energy of the wave in the question above?
   • What is the wavelength of yellow light emitted by a sodium lamp if the frequency of the radiation is $5.09x10^{14} s^{-1}$?

Practice Problems

1. What is the energy of a wave with a frequency of $4.5 x 10^{14} s^{-1}$?
2. What is the wavelength of the wave in question #1?

Further Practice

1. What is the energy of a wave with a frequency of $7.0 x 10^{14} s^{-1}$?
2. What is the wavelength of the wave with a frequency of 450 THz ($450 x 10^{12} s^{-1}$)?
3. What color would you see if you were to look at the wavelength in the question above?

Quiz Prep

• Topics: Energy and Energy flow.

Quiz Questions

1. What is energy?
2. How is light like a wave and a particle?
3. What is a catalyst?
4. What is activation energy of a chemical reaction?
5. How does a catalyst impact the activation energy of a chemical reaction?
6. Is the plot below representative of an endothermic reaction or exothermic reaction? Explain your answer.

Quiz Answers

1. The ability to do work.
2. It has properties of both when it is measured.
3. A factor that speeds up a chemical reaction.
4. The amount of energy required to get the reaction started.
5. Lowers the activation energy.
6. Endothermic, the reactants absorb energy to become the products.

Forms of Energy Practice

• Examples:

  • Food
  • Gasoline
  • Stretched spring
  • A muscle pulling on a bone

• Explain what form of energy is in the beginning and what the energy is being converted into in each situation.

• Example situation: Someone eats some food and then goes for a walk later.

• Example Answer: Chemical bonds are in the food store potential energy and then are eventually converted into mechanical energy when walking.

• Energy Conversions in Various Systems:

  • Nuclear reactor providing energy to homes
  • Solar cell providing energy to homes
  • Wind turbines providing power to homes
  • Batteries providing energy to a cell phone
  • Gasoline providing energy to a car
  • Generator providing energy to a home

Math Review

• Algebra:
  • Rearrange the equations before using them.
• Scientific Notation:
  • Short way of writing really large or small numbers.
• Dimensional Analysis:
  • Converting and using units.

Algebra Challenge

• Knowns: Wavelength
• Unknown: Energy
• Task: Create one equation that will allow for solving the energy with only the wavelength given.

Scientific Notation

• Coefficient: Number in front of multiplication sign.
• Exponent: To the top right of the ten. Basically multiplying two numbers $3.0x10^8 = (3.0)(10^8)$
• Need to be able to:
  • Switch to standard form
  • Perform all math operations

Energy Test Topics

• Movement of energy
• Heat as a primary example
  • Draw a picture of a rock being heated using arrows to show where the heat is going.
  • Draw another picture of the rock being immersed in room temperature water using arrows to show where the heat is going.
• Reaction coordinate diagrams
  • Endothermic vs Exothermic
  • Recognizing which has more energy in the end
• Systems and surroundings
  • Determining type of system (Open, closed, Isolated)
  • Is a thermometer part of the system or part of the surroundings?
• Forms of energy
  • Potential and kinetic
  • Chemical, mechanical, electrical, solar (light), etc.