Properties essays

Properties essays Chemical reactions are the heart of chemistry. People have always known that they exist. The Ancient Greeks were the firsts to speculate on the composition of matter. They thought that it was possible that individual particles made up matter. Later, in the Seventeenth Century, a German chemist named Georg Ernst Stahl was the first to postulate on chemical reaction, specifically, combustion. He said that a substance called phlogiston escaped into the air from all substances during combustion. He explained that a burning candle would go out if a candle snuffer was put over it because the air inside the snuffer became saturated with phlogiston. According to his ideas, wood is made up of phlogiston and ash, because only ash is left after combustion. His ideas soon came upon some contradiction. When metal is burned, its ash has a greater mass than the original substance. Stahl tried to cover himself by saying that phlogiston will take away from a substance's mass or that it had a negative mass, which contradicted his original theories. In the Eighteenth Century Antoine-Laurent Lavoisier, in France, discovered an important detail in the understanding of the chemical reaction combustion, oxigine (oxygen). He said that combustion was a chemical reaction involving oxygen and another combustible substance, such as wood. John Dalton, in the early Nineteenth Century, discovered the atom. It gave way to the idea that a chemical reaction was actually the rearrangement of groups of atoms called molecules. Dalton also said that the appearance and disappearance of properties meant that the atomic composition dictated the appearance of different properties. He also came up with idea that a molecule of one substance is exactly the same as any other People like Joseph-Lois Gay-Lussac added to Dalton's concepts with the postulate that the volumes of gasses tha...

An Introduction and Guide to Real Business Cycle Theory

An Introduction and Guide to Real Business Cycle Theory Real  business cycle  theory (RBC theory) is a class of macroeconomic models and theories that were first explored by American economist John Muth in 1961. The theory has since been more closely associated with another American economist, Robert Lucas, Jr., who has been characterized as â€Å"the most influential macroeconomist in the last quarter of the twentieth century.†Ã‚  Ã‚   Intro to Economic Business Cycles Before understanding real business cycle theory, one must understand the basic concept of business cycles. A business cycle is the periodic up and down movements in the economy, which are measured by fluctuations in real GDP and other macroeconomic variables. There are sequential phases of a business cycle that demonstrate rapid growth (known as expansions or booms) followed by periods of stagnation or decline (known as contractions or declines). Expansion (or Recovery when following a trough): categorized by an increase in economic activityPeak: The upper turning point of the business cycle when expansion turns to contractionContraction: categorized by a decrease in economic activityTrough: The lower turning point of the business cycle when contraction leads to recovery and/or expansion Real business cycle theory makes strong assumptions about the drivers of these business cycle phases. Primary Assumption of Real Business Cycle Theory The primary concept behind real business cycle theory is that one must study business cycles with the fundamental assumption that they are driven entirely by technology shocks rather than by monetary shocks or changes in expectations. That is to say that RBC theory largely accounts for business cycle fluctuations with real (rather than nominal) shocks, which are defined as unexpected or unpredictable events that affect the economy. Technology shocks, in particular, are considered a result of some unanticipated technological development that impacts productivity. Shocks in government purchases are another kind of shock that can appear in a pure real business cycle (RBC Theory) model. Real Business Cycle Theory and Shocks In addition to attributing all business cycle phases to technological shocks, real business cycle theory considers business cycle fluctuations an efficient response to those exogenous changes or developments in the real economic environment. Therefore, business cycles are â€Å"real† according to RBC theory in that they do not represent the failure of markets to clear or show an equal supply to demand ratio, but instead, reflect the most efficient economic operation given the structure of that economy. As a result, RBC theory rejects Keynesian economics, or the view that in the short run economic output is primarily influenced by aggregate demand, and monetarism, the school of thought that emphasizes the role of government in controlling the amount of money in circulation. Despite their rejection of RBC theory, both of these schools of economic thought currently represent the foundation of mainstream macroeconomic policy.