MODULE 1 UNIT 2.pdf

INCHEM 211 Department of Chemical Engineering Property...

INCHEM 211 Department of Chemical Engineering Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document. without Property of and for the exclusive usethe prior Reproduction, of SLU. written permission of SLU, storing is strictlysystem, in a retrieval prohibited. distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document. without the prior written permission of SLU, is strictly prohibited.  MODULE 1: FOUNDATIONS OF CHEMISTRY UNIT TWO - ENERGY ENGAGE ENGAGE ENGAGE ENGAGE ENGAGE ENGAGE ENERGY IN CHEMICAL REACTIONS The production of energy is one of the most important and pervasive aspects of chemistry. Think for a moment about all of the chemical reactions that we use to produce energy during the course of a typical day in our lives. We eat foods to produce the energy needed to maintain our biological function. We burn fossil fuels to produce the electrical energy that is central to our modern society, to produce heat for our homes, and to produce power for planes, trains and automobiles. We use ice cubes to cool our drinks, and we use heat to convert raw dough into baked bread. Green plants absorb energy from the Sun to fuel the chemical reactions that lead to their growth. All these examples illustrate the general point that chemical reactions involve energy. Some reactions, such as burning gasoline, release energy. Others, such as the splitting of water into hydrogen and oxygen, require the addition of energy. Over 90 percent of the energy produced in our society comes from chemical reactions, mostly from the combustion of coal, petroleum products and natural gas. Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document. without the prior written permission of SLU, is strictly prohibited.  EXPLORE EXPLORE EXPLORE EXPLORE EXPLORE EXPLORE FORMS OF ENERGY Objects, whether they are baseballs or molecules, can possess energy in two ways. Kinetic energy is the energy of motion. Kinetic energy increases as the speed of an object increases. For example, a car moving at 50 miles per hour (mph) has greater kinetic energy than it does when it travels at a speed of 40 miles per hour. For a given speed, the kinetic energy increases with increasing mass. Thus, a large sport-utility vehicle traveling at 55 mph has greater kinetic energy than a small sedan traveling at the same speed, because of the greater mass of the former. Atoms and molecules have mass and are in motion and therefore possess kinetic energy. An object can also possess potential energy by virtue of its position relative to other objects. Potential energy is, in essence, “stored” energy that results from the attraction and repulsion an object experiences in relation to other objects. FUN FACTS Did you know that the well-known philosopher, Aristotle, studied the concept of kinetic energy, but credit is actually given to Lord Kelvin in England for coining the term in his 1849 research? TYPES OF ENERGY Types of energy can be categorized into two broad categories – kinetic energy and potential energy. These are the two basic forms of energy. The different types of energy include thermal energy, radiant energy, chemical energy, nuclear energy, electrical energy, sound energy, elastic energy and gravitational energy. Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document. without the prior written permission of SLU, is strictly prohibited.  THERMAL (HEAT) ENERGY Thermal energy (also called heat energy) is produced when a rise in temperature causes atoms and molecules to move faster and collide with each other. The molecules and atoms that make up matter are moving all the time. When a substance heats up, the rise in temperature makes these particles move faster and bump into each other. Thermal energy is the energy that comes from the heated up substance. The hotter the substance, the more its particles move, and the higher its thermal energy. Here are some examples of thermal energy: a. warmth from the sun b. a cup of hot chocolate c. baking in an oven d. the heat from the heater FUN FACTS Geothermal energy is heat derived from within the sub-surface of the Earth’s surface. Thus, many countries want to take advantage of this. One of them is Iceland. Contrary to its name, Iceland is a home to many volcanoes and hot springs. Eighty seven percent of the country’s homes are heated using geothermal energy. CHEMICAL ENERGY Chemical energy is stored in the bonds that connect atoms with other atoms and molecules with other molecules. Because chemical energy is stored, it is a form of potential energy. When a chemical reaction takes place, the stored chemical energy is released. Here are some examples of chemical energy in action: a. Chemical energy in food: The food we eat contains stored chemical energy. As the bonds between the atoms in food loosen or break, a chemical reaction takes place, and new compounds are created. The energy produced from this reaction keeps us warm, helps us move, and allows us to grow. Different foods store different amounts of energy. b. Chemical energy in wood: Dry wood contains stored chemical energy. When you burn that wood in a fireplace, chemical energy is released and Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document. without the prior written permission of SLU, is strictly prohibited.  converted into thermal energy (heat) and light energy. And what about the wood? Following the chemical reaction, it's now turned into a new substance – ash. FUN FACTS Did you know that in today’s world, chemical energy is the most widely utilized source of energy? One common example is the matchstick. The chemical energy of the phosphorus compound at the tip of matchstick is used to get light and heat energy. NUCLEAR ENERGY Nuclear energy comes from the nucleus of atoms. The energy is released by nuclear fusion (nuclei are fused together) or nuclear fission (nuclei are split apart). Nuclear plants use nuclear fission of a radioactive element called uranium to generate electricity. Atoms consist of neutrons, protons and electrons (discussed from Module 1 Unit 1). They contain a nucleus, which is where nuclear energy comes from. Nuclear energy is released from an atom through either: a. Nuclear Fusion: Nuclei of atoms are combined or fused together. This is how the Sun produces energy. b. Nuclear Fission: Nuclei of atoms are split apart. This is the method by nuclear plants to generate electricity. FUN FACTS One of the benefits of nuclear energy is the nuclear waste being recyclable. That’s why this type of energy is seen as “clean” and sustainable energy. In fact, nuclear power plants supply 70% of America’s clean energy. ELECTRICAL ENERGY Electrical energy is a type of kinetic energy caused by moving electric charges. The amount of energy depends on the speed of the charges – the faster they move, the more electrical energy they carry. Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document. without the prior written permission of SLU, is strictly prohibited.  Let's imagine an electric charge is represented by a ball being thrown against a window. If you don't throw the ball very fast, it won't have enough energy to break the window. But if you throw the ball faster, it will have more energy and will be able to smash through the window. The faster you throw the ball, the more energy it will have to break the window. FUN FACTS At that time that electricity was discovered, it had already been used in many countries. However, one particular country called Ethiopia did not first recognize the power of electrical energy. Electricity was introduced to Ethiopia in 1896 after Emperor Menelik II ordered two newly invented electric chairs as a form of human capital punishment. However, when his purchases arrived, he then realized that these chairs were useless because the whole country had no electricity. Determined that his investment would not be completely wasted, Emperor Menelik II adopted one of the electric chairs for his imperial throne. RADIANT ENERGY Radiant energy is a form of electromagnetic energy. It can take the form of visible waves – which is what we call light energy – or invisible waves such as radio waves or x-rays. As the charges that cause the energy are moving, electrical energy is a form of kinetic energy. Here are some examples of radiant energy: a. Sunshine b. Solar cells c. X – rays d. Radiant heating systems FUN FACTS One of the interesting facts about radiant energy is it moves in a straight line, and it can be absorbed or reflected if the object cannot absorb it. Soil, for example, absorbs radiant energy, and this light and heat absorption warms seeds and roots in the soil to promote growth. Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document. without the prior written permission of SLU, is strictly prohibited.  SOUND ENERGY Sound is the movement of energy through a substance – like air or water – and is caused by vibrations. Solids, liquids and gases transmit sound as waves. Sound energy travels in the form of waves. Unlike light energy, sound cannot travel through a vacuum, because there are no atoms to transmit the vibration. ELASTIC ENERGY Elastic energy is a form of potential energy, because it is stored in the bonds between atoms in an object or substance when it is temporarily under stress. This stress could be due to the object being stretched or squashed. A force acting on an object can cause it to temporarily change its shape, such as when you stretch an elastic band, or squash a squishy ball with your hand. When this happens, elastic energy can be stored in the object, ready to be released when the object goes back to its original shape – when you let the elastic band go, or loosen your grip on the squishy ball. GRAVITATIONAL ENERGY Gravity is a force which tries to pull two objects toward each other. Earth's gravity is what keeps you on the ground and what causes objects to fall. The Earth has gravity. Gravity holds everything close to this planet. Trees, water, animals, buildings, and the air we breathe are all held here by gravity. The planets, their moons, and the stars in the universe have gravity. Even our own bodies have gravity. The Earth's gravity is far stronger than our own so we don't notice the gravity our bodies have. The Earth's tides are caused by the moon's gravitational pull on the oceans. Tides are the rise and fall of the ocean level as related to the shoreline. Gravitational energy is the energy stored in an object due to its height above the Earth (e.g. if it's further away or closer to the ground). It is a form of potential energy. There are other types of energy that can be included but these are the common examples. You can also discover on your own the other types of energy that are not included in this module. EXPLAIN EXPLAIN EXPLAIN EXPLAIN EXPLAIN EXPLAIN LAW ON ENERGY We have seen that the potential energy of a system can be converted into kinetic energy and vice versa. We have also seen that energy can be Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document. without the prior written permission of SLU, is strictly prohibited.  transferred back and forth between a system and surroundings in any form of energy. In general, energy can be converted from one form to another, and it can be transferred from one part of the universe to another. How are all these changes in energy related? One of the most important observations in science is that energy can neither be created nor destroyed: energy is conserved. Any energy that is lost by any system must be gained by the surroundings and vice versa. This is known as the Law of Conservation of Energy. Law of Conservation of Energy states that energy can neither be created nor destroyed - only converted from one form of energy to another. ELABORATE ELABORATE ELABORATE ELABORATE Formative Assessment (Graded Assignment) 1. Identify the type of energy of the following materials: (It is possible that one word/material can fall under more than one type of energy) a) batteries; b) food; c) solar cells; d) ultraviolet rays; e) lightning; f) uranium; g) microwave; h) ball held above the ground; i) rubber band; and k) gun powder. 2. Suppose a ball is tossed upward, a) What happens to the kinetic energy of the ball as it goes higher? Why? b) Does the potential energy of the ball increases or decreases as it moves upward? Why? c) At what point does the potential energy of the ball reaches its maximum? Explain your answer. EVALUATE EVALUATE EVALUATE EVALUATE You have reviewed some important concepts of energy and acquired additional and new knowledge on some important advancement. You should be able to apply these concepts. Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document. without the prior written permission of SLU, is strictly prohibited.  References: Brown, Le May & Bursten. (1997). Chemistry, The Central Science, 7th Ed. USA: Prentice Hall International. www.solarschools.net Property of and for the exclusive use of SLU. Reproduction, storing in a retrieval system, distributing, uploading or posting online, or transmitting in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise of any part of this document. without the prior written permission of SLU, is strictly prohibited.