Energy Transformations Mr. Carters Science Class The 1 st Law of thermodynamics Write down the 1 st Law of Thermodynamics from memory Matter and energy cannot be created or destroyed. Matter and energy cannot be created or destroyed. They can change forms, though. They can change forms, though. Chemical Reactions In chemical reactions energy just changes form from one form to another. In chemical reactions energy just changes form from one form to another. For example when a candle burns the energy stored in the candle wax get converted thermal energy (heat) and light. For example when a candle burns the energy stored in the candle wax get converted thermal energy (heat) and light. All chemical reactions fit into 2 categories Exothermic Reactions Endothermic reactions Exothermic Reactions Exothermic reactions are reactions that produce more energy than they require Exothermic reactions are reactions that produce more energy than they require Example: the chemical reaction that takes place in a hot pack to produce heat. Example: the chemical reaction that takes place in a hot pack to produce heat. The chemical energy stored in the hot pack is converted to thermal energy. The chemical energy stored in the hot pack is converted to thermal energy. Endothermic Reactions Endothermic reactions are reactions that require more energy than they produce Endothermic reactions are reactions that require more energy than they produce Example: When you boil a used-up hot pack to make it reusable. Example: When you boil a used-up hot pack to make it reusable. The thermal energy from the stove is converted back into chemical energy in the hot pack. The thermal energy from the stove is converted back into chemical energy in the hot pack. 4 important chemical reactions 1. Photosynthesis 2. Combustion 3. Aerobic Cellular Respiration 4. Fermentation 1. Photosynthesis CO 2 + H 2 O + sunlight C 6 H 12 O 6 + O 2 CO 2 + H 2 O + sunlight C 6 H 12 O 6 + O 2 Balance the equation now. Balance the equation now. Photosynthesis is performed by autotrophs Photosynthesis is performed by autotrophs Autotroph= plants, algae, and photosynthetic bacteria. Autotroph= plants, algae, and photosynthetic bacteria. 1. Photosynthesis Carbohydrates are the product Carbohydrates are the product Oxygen is the by-product Oxygen is the by-product 1. Photosynthesis Carbohydrates are the primary energy source for the majority of living things (us included. Carbohydrates are the primary energy source for the majority of living things (us included. Carbohydrates are also called sugars and often taste sweet. Carbohydrates are also called sugars and often taste sweet. Carbohydrates have an ose suffix. Carbohydrates have an ose suffix. Examples: sucrose, fructose, maltose, cellulose Examples: sucrose, fructose, maltose, cellulose 2. Combustion Combustion is the process of burning carbon-and-hydrogen-containing compounds (hydrocarbons)in the presence of oxygen Combustion is the process of burning carbon-and-hydrogen-containing compounds (hydrocarbons)in the presence of oxygen Hydrocarbon + O 2 CO 2 + H 2 O + Energy Hydrocarbon + O 2 CO 2 + H 2 O + Energy 2. Combustion Balance the equation for the combustion of propane gas (C 3 H 8 ) Balance the equation for the combustion of propane gas (C 3 H 8 ) C 3 H 8 + O 2 CO 2 + H 2 O + Energy C 3 H 8 + O 2 CO 2 + H 2 O + Energy Name 4 things that humans use combustion reactions for. Name 4 things that humans use combustion reactions for. 3. Aerobic Cellular Respiration Cellular respiration is the process of getting energy from the sugars in food in the presence of oxygen. Cellular respiration is the process of getting energy from the sugars in food in the presence of oxygen. C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + 36ATP C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + 36ATP Balance the equation now. Balance the equation now. 3. Aerobic Cellular Respiration Cellular respiration happens in the cells of an organisms Cellular respiration happens in the cells of an organisms Cellular respiration (breathing) is why most organisms need oxygen (including us) Cellular respiration (breathing) is why most organisms need oxygen (including us) This is why we need to eat food (and mainly carbohydrates). This is why we need to eat food (and mainly carbohydrates). Cellular respiration occurs in the mitochondria of the cell. Cellular respiration occurs in the mitochondria of the cell. For this reason, the mitochondria are known as the powerhouses of the cell. For this reason, the mitochondria are known as the powerhouses of the cell. ADP ATP Adenosine Triphosphate Adenosine Triphosphate ATP is created by adding a phosphate group to ADP. This requires energy. ATP is created by adding a phosphate group to ADP. This requires energy. ATP ADP ATP is used up for energy by the cell and converted back into ADP (Adenosine Diphosphate) ATP is used up for energy by the cell and converted back into ADP (Adenosine Diphosphate) ATP or ADP? Create your own analogy! Create your own analogy! 4. Fermentation Fermentation is the process of converting sugars into ATP WITHOUT oxygen. Fermentation is the process of converting sugars into ATP WITHOUT oxygen. Fermentation is also called anaerobic cellular respiration Fermentation is also called anaerobic cellular respiration C 6 H 12 O 6 CO 2 + C 2 H 6 O + 2ATP C 6 H 12 O 6 CO 2 + C 2 H 6 O + 2ATP Balance the equation now. Balance the equation now. 4. Fermentation Fermentation is often performed by yeast and bacteria. Fermentation is often performed by yeast and bacteria. Yeast produce CO 2 gas as they ferment, making bread rise. Yeast produce CO 2 gas as they ferment, making bread rise. Yeast also make beer alcoholic (ethanol) and foamy (CO 2 ). Yeast also make beer alcoholic (ethanol) and foamy (CO 2 ). Fermentation Some fermenting bacteria produce Lactic Acid instead of alcohol. Some fermenting bacteria produce Lactic Acid instead of alcohol. Lactic acid makes fermented foods taste sour or tangy. Lactic acid makes fermented foods taste sour or tangy. Lactic Acid Fermentation is used to produce sour products like yogurt, sour cream, kimchi, pickles, sourkraut, etc. Lactic Acid Fermentation is used to produce sour products like yogurt, sour cream, kimchi, pickles, sourkraut, etc. 4. Fermentation Anaerobic cellular respiration also occurs in our muscles during VIGOROUS exercise. Anaerobic cellular respiration also occurs in our muscles during VIGOROUS exercise. If your body is working so hard that your lungs cant keep up (you cant get enough Oxygen to your muscles), your muscle cells have to do anaerobic cellular respiration If your body is working so hard that your lungs cant keep up (you cant get enough Oxygen to your muscles), your muscle cells have to do anaerobic cellular respiration Aerobic Anaerobic What is Air? Air is not a pure substance, but a mixture of several gases. Air is not a pure substance, but a mixture of several gases. 78% of air is Nitrogen (N 2 ) which is inert (does not easily react with other molecules). 78% of air is Nitrogen (N 2 ) which is inert (does not easily react with other molecules). 21% of Air is Oxygen (O 2) 21% of Air is Oxygen (O 2) 0.9% of Air is Argon (Ar), which is inert because it is a noble gas 0.9% of Air is Argon (Ar), which is inert because it is a noble gas 0.037% of air is Carbon Dioxide (CO 2 ) 0.037% of air is Carbon Dioxide (CO 2 ) Rising Carbon Dioxide CO 2 levels in the atmosphere are increasing. CO 2 levels in the atmosphere are increasing. This is mostly because humans are combusting fossil fuels for energy and transportation. This is mostly because humans are combusting fossil fuels for energy and transportation. We are also cutting down forests and replacing them with cities and farms. We are also cutting down forests and replacing them with cities and farms. Forests REMOVE CO 2 and replace it with O 2 Forests REMOVE CO 2 and replace it with O 2 Animals, like cows and people, REMOVE O 2 Animals, like cows and people, REMOVE O 2 and replace it with CO 2 The greenhouse effect CO 2 is called a greenhouse gas because it surrounds the planet and traps heat and light. CO 2 is called a greenhouse gas because it surrounds the planet and traps heat and light. This is called the greenhouse effect and it is causing global mean temperatures to increase. This is called the greenhouse effect and it is causing global mean temperatures to increase. The greenhouse effect also causes the worlds climate to get screwed up by increasing global temperatures. The greenhouse effect also causes the worlds climate to get screwed up by increasing global temperatures.