Writing Chemical Writing Chemical EquationsEquations

Ch 8Ch 8

Chemical EquationsChemical Equations

Give a lot of information about a Give a lot of information about a chemical reaction.chemical reaction.

Writing Chemical Equations: Writing Chemical Equations: Symbols & TermsSymbols & Terms

Reactants: starting substancesReactants: starting substances Products: ending substancesProducts: ending substances +: separates reactants (or products) from each other+: separates reactants (or products) from each other →→: yields, separates reactants from products: yields, separates reactants from products (g): substance is a gas(g): substance is a gas (l): substance is a liquid(l): substance is a liquid (aq): aqueous, substance is dissolved in water(aq): aqueous, substance is dissolved in water (s): substance is a solid(s): substance is a solid

More SymbolsMore Symbols

ΔΔ: when placed over an arrow, : when placed over an arrow, means the reaction has been heated.means the reaction has been heated.

Pt: when a chemical formula is Pt: when a chemical formula is placed over an arrow, it means that placed over an arrow, it means that that substance is a CATALYST that substance is a CATALYST Catalyst: a substance that speeds up a Catalyst: a substance that speeds up a

reaction by its mere presence, is not reaction by its mere presence, is not used up in the reaction.used up in the reaction.

Word EquationsWord Equations

Use names to represent substances used in a Use names to represent substances used in a chemical reactionchemical reaction

Ex.Ex.Hydrogen gas reacts with bromine gas to produce Hydrogen gas reacts with bromine gas to produce

hydrogen bromide gas.hydrogen bromide gas.Hydrogen (g) + bromine (g) Hydrogen (g) + bromine (g) → hydrogen → hydrogen

bromide bromide (g) (g)

Skeleton EquationsSkeleton Equations

Use the formulas for substances Use the formulas for substances instead of their namesinstead of their names

Ex.Ex.Hydrogen (g) + bromine (g) Hydrogen (g) + bromine (g) → hydrogen → hydrogen

bromide bromide (g)(g)

HH22 (g) + Br (g) + Br22 (g) → HBr (g) (g) → HBr (g)