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Chemical Reactions
Vocabulary pertaining to chemical reactions
Term | Definition |
---|---|
chemical reaction | a change in which one or more substances are converted into new substances |
reactants | substances that react On the left side of the arrow |
products | new substance that is produced On the right side of the arrow |
Law of Conservation of Mass | says that matter can neither be created or destroyed |
chemical equations | a way to describe a chemical reaction using chemical formulas and other symbols Ex. H2 + O -->H2O |
coefficient | a number that represents the number of "units" of each substance taking part in a reaction. |
balanced chemical equation | a reaction that has the same number of atoms of "each element" on "both sides" of the equation. Ex. H2+O2-->H2O Balance: 2H2+ O2-->2H2O |
combustion reaction | occurs when a substance reacts with oxygen to produce energy in the form of heat and light |
synthesis reaction | two or more substances combine to form another substance A+B-->AB Ex. 2H2+O2-->2H2O |
decomposition reaction | occurs when one substance breaks down, or decomposes, into two or more substances. (opposite of synthesis reaction) AB-->A+B Ex. 2H2O-->2H2+O2 |
single displacement reaction | occurs when one element replaces another element in a compound. A+BC-->AC+B Ex. Cu+2AgNO3-->Cu(NO3)2 + 2Ag |
Double displacement reaction | occurs when the "positive Ion" of one compound replaces the "positive ion" of the other to form "two new" compounds. AB+CD--> AD+CB Ex. Ba(NO3)2 +K2SO4-->BaSO4 + 2KNO3 |
oxidation | describes the loss of electrons in a chemical reaction |
reduction | describes the gain of electrons in a chemical reaction |
precipitant | an insoluble compound that comes out of solution during a double displacement reaction. Ex. when two liquids react they form a solid (precipitant) and a liquid |
exergonic reaction | chemical reaction that releases energy in the form of heat or light. (Less energy is required to break the original bonds than is "released" when new bonds form) |
exothermic reaction | when the energy given off from a chemical reaction is primarily in the form of heat Ex. Wood burning, dynamite exploding, iron rusting These reaction supply most of the power used in homes and industries. (Vinegar and steel wool --> reaction felt warm |
endergonic reaction | a chemical reaction that requires more energy to break bonds than is released when new ones are formed. The energy "absorbed" can be in the form of light, thermal energy or electricity. |
endothermic reaction | when the energy needed is in the form of thermal energy. Ex. lemon juice and baking soda-->absorbed heat so reaction felt cold |
catalyst | a substance that is added to a chemical reaction that speeds up the reaction without being permanently changed itself |
inibitor | a substance that is used to slow down a reaction Ex. lemon juice stops the reaction that causes apples to brown after they are cut. |