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Unit 3: Chemical Equations, Reactions & Stoichiometry

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Chemical Reation
Is a change in which one or more substances are converted into new substances.
Chemical Equation
a representation of a chemical reaction that uses symbols to show the relationship between the reactants and the products.
4 Indications of a chemical reaction
precipitate, change in color, increase or decrease in temperature, and/ or production of gas.
Reactants
the elements or compounds that enter into a chemical reaction
Products
the elements or compounds produced by a chemical reaction
Precipitate
a solid that forms and settles out of a liquid mixture
Coefficient
A number in front of a chemical formula in an equation that indicates how many molecules or atoms of each reactant and product are involved in a reaction.
Aqueous
dissolved in water
Catalyst
a substance that initiates or accelerates a chemical reaction without itself being affected
Synthesis Reaction
a reaction in which two or more substances combine to form a new compound
Decomposition Reaction
separation of a substance into two or more substances that may differ from each other and from the original substance
Single-displacement Reaction
A reaction in which one element or radical takes the place of another element or radical in a compound
Double-displacement Reaction
a reaction in which a gas, a solid precipitate, or a molecular compound forms from the apparent exchange of atoms or ions between two compounds
Combustion Reaction
a chemical reaction that occurs when a substance reacts with oxygen, releasing energy in the form of heat and light
Activity series of metals
lists metals in order of decreasing reactivity
Stoichiometry
the relation between the quantities of substances that take part in a reaction or form a compound (typically a ratio of whole integers)
Mole
the molecular weight of a substance expressed in grams
Avogadro's number
number of representative particles in a mole, 6.02 X 10^23
Molar Mass
the mass of one mole of a pure substance
Formula Mass
the sum of the average atomic masses of all the atoms represented in the formula of any molecule, formula unit, or ion
Percentage Composition
the percentage by mass of each element in a compound
Empirical Formula
a chemical formula showing the ratio of elements in a compound rather than the total number of atoms
Molecular Formula
a chemical formula based on analysis and molecular weight
Mole Ratio
the relative number of moles of the substances required to produce a given amount of product in a chemical reaction
Limiting Reactant
the substance that controls the quantity of product that can form in a chemical reaction
Excess reactant
The substance that is not used up completely in a reaction
Actual yield
the measured amount of a product obtained from a reaction
Theoretical yield
the maximum amount of product that can be produced from a given amount of reactant
Percentage yield
The ratio of the actual yield to the theoretical yield, multiplied by 100