Unit 9 Notes – Gas Laws Background – Science Laws, Theories and Hypotheses Laws are generalizations or universal relationships related to the way that some aspect of the natural world behaves under certain conditions. Therefore, laws are different from hypotheses and theories in science. An initial investigation provides some evidence (data) that must be explained and tested further. This tentative explanation, or hypothesis, forms the foundation for further investigations. If the hypothesis is supported, more investigations are done. As it becomes stronger, it becomes more predictive and explanatory. At this point, the hypothesis becomes a theory: a broad explanation that has been supported with data and is a well substantiated, consistent explanation for a natural occurrence. Theories evolve as a result of continued testing. When evidences is found that is inconsistent with or not predicted by the theory, it must be changed. In some cases, a new theory must be proposed and tested further. I. Kinetic Theory of Gases This theory helps us understand why gases behave the way they do and give us insight into the behavior of solids and liquids. There are five basic postulates of this theory. 1.Particles in a gas have no volume and are very far apart. 2.Particles in a gas move in straight line paths and random directions. 3.Particles in a gas collide frequently with the sides of the container and less frequently with each other. All collisions are elastic (no energy is gained or lost as a result of the collisions). 4.Particles in a gas do not attract or repel one another. There is no intermolecular attractions. 5.The average kinetic energy of all of the gas particles in a sample is proportional to the temperature of that gas sample. II. Temperature Temperature is a measure of the average kinetic energy of a substance. Many problems we will be working use equations which include temperature, it is important to be able to convert between Celsius and Kelvin. 0 Kelvin is absolute zero; there are not negative numbers on the Kelvin scale. A. Converting between Celsius and Kelvin. Celsius to Kelvin K = o C + 273 Kelvin to Celsius o C = K – 273 B. Example: Convert: –167 o C to Kelvin 1100 o C to Kelvin 321 Kelvin to Celsius
Unit 9 Notes – Gas Laws
Jul 05, 2023
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