chemical reactions and equations

chemical reaction

the process in which one or more substances are converted into new substances with different chemical and physical properties.

indicators of a chemical reaction

production of a gas

color change

formation of a precipitate

evolution of energy (heat and/or light)

exothermic reaction

energy is released during the reaction

*burning coal

endothermic reaction

energy is absorbed during the reaction

*cooking

activation energy

the energy needed to start a chemical reaction

catalyst

a substance that lowers the activation energy of a reaction

reactants

substances that enter into a chemical reaction

products

substances produced by a chemical reaction

chemical equation

a condensed statement that uses chemical formulas to identify the reactants and products in a chemical reaction.

+

used to separate reactants or products.

means- “reacts with” or “and”

→

separates reactants from products

means- “yields” or produces

(s)

refers to a solid

(l)

refers to a liquid

(g)

refers to a gas

(aq)

refers to a solid chemical dissolved in water

⇌

shows a chemical reaction that can be reversed

indicates that heat is added to the reactin

word equation

written with names of reactants and products

formula equation

written with chemical symbols and formulas

law of conservation of mass

mass is neither created nor destroyed in a chemical reaction.

coefficients

a whole number that appears in front of a formula in a chemical equation.

used to balance the atoms on either side of a chemical equation.