Endothermic and Exothermic Chemical Reactions

Many chemical reactions release energy in the form of heat, light, or sound. These are exothermic reactions. Exothermic reactions may occur spontaneously and result in higher randomness or entropy (ΔS 0ï » ¿) of the system. They are denoted by a negative heat flow (heat is lost to the surroundings) and decrease in enthalpy (ΔH 0). In the lab, exothermic reactions produce heat or may even be explosive. There are other chemical reactions that must absorb energy in order to proceed. These are endothermic reactions. Endothermic reactions cannot occur spontaneously. Work must be done in order to get these reactions to occur. When endothermic reactions absorb energy, a temperature drop is measured during the reaction. Endothermic reactions are characterized by positive heat flow (into the reaction) and an increase in enthalpy (ΔH). Examples of Endothermic and Exothermic Processes Photosynthesis is an example of an endothermic chemical reaction. In this process, plants use the energy from the sun to convert carbon dioxide and water into glucose and oxygen. This reaction requires 15MJ of energy (sunlight) for every kilogram of glucose that is produced: sunlight 6CO2(g) H2O(l) C6H12O6(aq) 6O2(g) Other examples of endothermic processes include: Dissolving ammonium chloride in waterCracking alkanesNucleosynthesis of elements heavier than nickel in starsEvaporating liquid waterMelting ice An example of an exothermic reaction is the mixture of sodium and chlorine to yield table salt. This reaction produces 411 kJ of energy for each mole of salt that is produced: Na(s) 0.5Cl2(s) NaCl(s) Other examples of exothermic processes include: The thermite reactionA neutralization reaction (e.g., mixing an acid and a base to form a salt and water)Most polymerization reactionsCombustion of a fuelRespirationNuclear fissionCorrosion of metal (an oxidation reaction)Dissolving an acid in water Demonstrations You Can Perform Many exothermic and endothermic reactions involve toxic chemicals, extreme heat or cold, or messy disposal methods. An example of a quick exothermic reaction is dissolving powdered laundry detergent in your hand with a bit of water. An example of an easy endothermic reaction is dissolving potassium chloride (sold as a salt substitute) in your hand with water. These endothermic and exothermic demonstrations are safe and easy: Exciting Exothermic Reactions to Try: Heat things up with one of these simple exothermic reaction demonstrations.Create an Endothermic Reaction: Some endothermic reactions get cold enough to cause frostbite. Heres an example of a reaction safe enough for kids to touch.How to Create an Exothermic Chemical Reaction: Some exothermic reactions produce flames and get extremely hot (like the thermite reaction). Here is a safe exothermic reaction that produces heat but wont start fires or cause a burn.Make Hot Ice From Vinegar and Baking Soda: Sodium acetate or hot ice can be used as either an endothermic or exothermic reaction, depending on whether you are crystallizing or melting the solid. Endothermic vs Exothermic Comparison Heres a quick summary of the differences between endothermic and exothermic reactions: Endothermic Exothermic heat is absorbed (feels cold) heat is released (feels warm) energy must be added for reaction to occur reaction occurs spontaneously disorder decreases (ΔS 0) entropy increases (ΔS 0) increase in enthalpy (+ΔH) decrease in enthalpy (-ΔH) Endergonic and Exergonic Reactions Endothermic and exothermic reactions refer to the absorption or release of heat. There are other types of energy which may be produced or absorbed by a chemical reaction. Examples include light and sound. In general, reactions involving energy may be classified as endergonic or exergonic, An endothermic reaction is an example of an endergonic reaction. An exothermic reaction is an example of an exergonic reaction. Key Facts Endothermic and exothermic reactions are chemical reactions that absorb and release heat, respectively.A good example of an endothermic reaction is photosynthesis. Combustion is an example of an exothermic reaction.The categorization of a reaction as endo- or exothermic depends on the net heat transfer. In any given reaction, heat is both absorbed and released. For example, energy must be input into a combustion reaction to start it (lighting a fire with a match), but then more heat is released than was required. Resources and Further Reading Qian, Y.†Z., et al. â€Å"Diverse Supernova Sources for the r†Process.† The Astrophysical Journal, vol. 494, no. 1, 10 Feb. 1998, pp. 285-296, doi:10.1086/305198.Yin, Xi, et al. â€Å"Self-Heating Approach to the Fast Production of Uniform Metal Nanostructures.† Chemistry of Nanomaterials for Energy, Biology and More, vol. 2, no. 1, 26 Aug. 2015, pp. 37-41, doi:10.1002/cnma.201500123.

Climate Change And Global Warming - 1630 Words

Climate Related Threats Global warming will lead to uncontrollable devastation such as famine, war, and economic instability. Climate change will accelerate the dislocation of hundreds of millions of people and the extinction of many species. The negative effects of climate change are obvious on every continent. Professor Le Quere, director of the Tyndall Centre for Climate Change Research at the University of East Anglia said, The human influence on climate change is clear. The atmosphere and oceans are warming, the snow cover is shrinking, the Arctic sea ice is melting, sea levels are rising, the oceans are acidifying, some extreme weather events are on the rise, ecosystems and natural habitats will be upset. Climate change threatens food security and world economies† (The Independent). This drastic warning by Professor Le Quere shows no one is immune to global warming. Change in climate will endanger world fragility and the global food supply. The effect of global warming will lead to war an d famine, which are so far advanced that they threaten the existence of life on our planet. Wieland 2. When global warming strikes, we will see threats toward the global food production and supply. As temperatures rise and drought starts, the production of things like livestock, wheat, fruit, corn, and fisheries decrease. Different parts of the planet that have adequate rainfall for crop production now, will need irrigation systems to support their yields. IrrigationShow MoreRelatedGlobal Warming And Climate Change974 Words   |  4 Pagesabout global warming, whether it is true or false. Is there evidence to prove that global warming has impacted the climate due to the rise in the earth’s temperature? Climate change is a problem that is worldwide that should be reviewed. The rise in the earth’s temperature has caused some impact to the weather and climate changes to many places worldwide. This rise in temperature has the potential of causing drastic changes to the earth in many ways. It is time to view the global warming concernsRead MoreClimate Change Of Gl obal Warming924 Words   |  4 Pages Figure 0.1 shows the different effects of global warming. Global warming is the warming of our planet at an extreme rate. The Earth’s climate has warmed by 7.8OC since 1880. (Quick facts about science, 2015). What causes global warming? The cause of global warming is the carbon dioxide. This acts like a blanket. Protecting the earth, and heating the earth. Sun rays would normally bounce around the earth, but with the blanket, the sun rays heat the blanket which heats the earth. (Petersen ScienceRead MoreGlobal Warming And Climate Change1398 Words   |  6 Pages Global warming and climate change have been frequent topics of discussion over the past several years. Although people tend to focus on the politics, it is important to look past the media aspects of it into the cold hard facts of what our Earth is currently experiencing, and what has caused it in the first place. The cause of climate change includes natural causes, but human causes are what is generating such a rapid global temperature change. It’s time that the ways in which humanity affectsRead MoreClimate Change And Global Warming1060 Words   |  5 PagesClimate change (Klaus) 1000 The terms â€Å"global warming†, â€Å"climate change† or â€Å"greenhouse effect† have become more than just parts of the popular lexicon as they rather are subject of public discussions, scientific research or political debates. Despite the popularity and the ubiquity of these terms, the public’s theoretical and conceptual understanding of them and their causal relations is often based on superficial knowledge and buzzwords or caricatures outlined and depicted in several popular mediaRead MoreClimate Change : Global Warming1194 Words   |  5 PagesDonya Curtis April 19, 2017 English 1001-rough draft Global Warming Global warming is one facet of the broader term climate change. It is the increase in the average temperature of the Earth s surface air and oceans from the mid 20th century and the projected continuation. The Global warming is primarily the consequence of building up greenhouse gasses in the atmosphere. Emission rates for most important anthropogenic greenhouse gas, CO2, have increased 120 fold in the past 140 years. WhileRead MoreClimate Change and Global Warming1074 Words   |  5 PagesClimate change and Global Warming are out of control. This means that, no matter what policies, processes or actions are implemented, the Earth as we know it will never be the same again. There is significant evidence to support this hypothesis. The dilemma becomes whether we can limit the damage and adapt to a new status quo or not. Rising sea levels and the damage caused by this phenomenon has irreversible impacts on coastlines worldwide. Damage to sensitive reef systems cannot be fixed. This alsoRead MoreClimate Change And Global Warming1022 Words   |  5 PagesWhat = Climate Change Who = Emma, Aoife, Julia, Rachael, Mariah and Cà ©line What is it? Climate Change is a change in the demographic distribution of weather patterns, and related change in oceans, land surfaces and ice sheets, happening over time scales of decades or longer. It’s the world’s greatest threat. Climate change is the change in temperature over a period of time. It involves the greenhouse effect and global warming. Where is it? It is an issue affecting everyone everywhere. ClimateRead MoreClimate Change And Global Warming1474 Words   |  6 Pagesphenomenon, known as â€Å"smog† became an often daily occurrence in big, urbanized cites across the globe. Also, Al Gore’s book, An Inconvenient Truth, popularized the issue of climate change and global warming as a result of the damage that the modern world has done to the atmosphere. He noted that people resist the facts about climate change due to the inconvenience of changing their lifestyles. But, uninhibited industrialization of several countries has led to intense modernization and revolution of theRead MoreClimate Change And Global Warming928 Words   |  4 PagesThis paper will discuss climate change and global warming on the economy. The paper also gives a description on climate change and global warming. As well as what it hold for future business owners. It will also discuss what the government is doing about climate change/global warming. Climate change is a long-term shift in the statistics of the weather (including its averages). For example, it could show up as a change in climate normal (expected average values for temperature and precipitation)Read MoreClimate Change And Global Warming1412 Words   |  6 Pages Earth’s climate has been changed for hundreds of year dating back to the beginning of man to the ice age and today, and with that change came scientists who have been keeping track and gathering data on these changes in the climate. The climate is the source of life it provides a secure environment setting for life forms to thrive without a proper climatic setting life would begin to dwindle and eventually all life forms would go extinct. But why is the climate so important moreover exactly what

How I Exhibit the Four Pillars of the National Honor Society Essay Example For Students

How I Exhibit the Four Pillars of the National Honor Society Essay The National Honor Society is based off of four pillars: Scholarship, Leadership, Service, and Character. School is an extremely important part of anyone’s life, and I feel blessed that I have had the opportunity to attend Lutheran schools from Kindergarten until the present. Our Shepherd Lutheran and Lutheran High Northwest have helped me to grow in my faith and to continue to grow academically as well. Attending these schools has also allowed me to participate in many different extra-curricular activities such as Varsity Soccer in my freshman year, Varsity Track my sophomore year, Pit Band for school musicals, Jazz band, and Pep band. This 2009-2010 school year I also have the opportunity to be the First Chair Flute and Piccolo in regular Concert Band and the other band functions which will provide me with an opportunity to gain experience in leadership which will help me in college and in my future career. Service is an important activity to participate in. During the past two years I have helped my mom and the rest of the committee at my church with funeral luncheons. When there is a funeral at my church the family of the deceased has the option of having a luncheon at the church, and if they choose, following the funeral, the committee that my mom is on takes care of getting the food that the family wants, serving the food, and then cleaning up after the luncheon is over. When they need help I also go and help out. Also, my family recently became a Foster family for the Michigan Humane Society. In November of this year, I am going on a mission trip to Madrid, Spain, with my cousin, who is a pastor, and a group from his church, Valley Springs, in Roseville, California. Our main aim is going to be talking to the college students there and trying to plant churches. We are going to be helping them work on their English, and I will get to use my Spanish. I have also had the opportunity to work in the Lutheran Church of the Redeemer nursery which was my first paying job. Every Sunday morning I am in the nursery from 9 until 12, or later if needed, watching peoples children up to four years of age while they attend church.