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When a piece of magnesium is added to dilute hydrochloric acid, fizzing occurs and hydrogen gas is released from the mixture. The fizzing is evidence that a(n) 1____ has occured between magnesium and hydrochloric acid. The name given to either magnesium or hydrochloric acid in this case is 2____, and the hydrogen gas that is released is called a(n) 3____ of the reaction. Some other indications that reactions have occured might be change of color or 4____, or formation of a solid 5____. If a thermometer is placed into a mixture undergoing a reaction, u might observe that the temperature has gone up or down, indicating that 6____ was being released or absorbed. The shorthand form by which a reaction is represented is called a(n) 7____. In using this method of representation, u must satisfy the 8____, a principle that states that matter is neither created or destroyed. In order to satisfy this principle, u normally select the proper numerical 9____ to indicate the number of units of each substance taking part in the chemical change.

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