Science Perspective

Science Perspective (Student Name

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List the two types of chemical reactions , and discuss the reactions in terms of the energy diagrams (activation energy , etc

The two types of chemical reactions are exothermic and Endothermic reactions . In case of exothermic reactions , energy is released in the form of heat , light or sound . Exothermic reactions may occur spontaneously . Endothermic reaction is one which must absorb energy in to proceed . Endothermic reactions cannot occur spontaneously . Work must be done in to get these reactions to occur . When

endothermic reactions absorb energy , a temperature drop is measured during the reaction

Photosynthesis is an example of an endothermic chemical reaction and in this process (reaction ) 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

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

Figure : Energy Diagram

In endothermic reactions the reactants have a lower energy level than the products . The difference between these two energy levels is the energy gained from the surroundings in the reaction . In an exothermic reaction , reactants have a higher energy level than the products . The difference between these two energy levels is the energy released to the surroundings in the reaction . Usually some extra energy is needed to get the reaction to start . This is called the activation energy

2 . List the 3 types of radioactive decay , and describe how the energy /particles are emitted in of lowest to highest energy

Radioactive Decay : Many nuclei are radioactive and hence they are unstable , and will eventually decay by emitting a particle , transforming the nucleus into another nucleus , or into a lower energy state . A chain of decays takes place until a stable nucleus is reached . During radioactive decay , principles of conservation apply and they are conservation of energy , conservation of momentum (linear and angular conservation of charge and conservation of nucleon number .There are three common types of radioactive decay , alpha , beta , and gamma

Figure : Penetration Capacity of alpha , beta and gamma

Alpha decay : In alpha decay , the nucleus emits an alpha particle an alpha particle is essentially a helium nucleus , so it 's a group of two protons and two neutrons . A helium nucleus is very stable . Alpha particles do not travel far in air before being absorbed this makes them very safe for use in smoke detectors , a common household item . An example of an alpha decay involves Uranium-238 Beta Decay : A beta particle is often an electron , but can also be a positron , a positively-charged particle that is the anti-matter equivalent of the electron . If an electron is involved , the number of neutrons in the nucleus decreases by...