1. Writing Chemical Equations Ch 8

2. Chemical Equations Give a lot of information about a chemical reaction. Give a lot of information about a chemical reaction.

3. Writing Chemical Equations: Symbols & Terms Reactants: starting substances Reactants: starting substances Products: ending substances Products: 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

4. More Symbols Δ: when placed over an arrow, means the reaction has been heated. Δ: when placed over an arrow, means the reaction has been heated. Pt: when a chemical formula is placed over an arrow, it means that that substance is a CATALYST Pt: when a chemical formula is placed over an arrow, it means that that substance is a CATALYST Catalyst: a substance that speeds up a reaction by its mere presence, is not used up in the reaction. Catalyst: a substance that speeds up a reaction by its mere presence, is not used up in the reaction.

5. Word Equations Use names to represent substances used in a chemical reaction Use names to represent substances used in a chemical reaction Ex. Ex. Hydrogen gas reacts with bromine gas to produce hydrogen bromide gas. Hydrogen gas reacts with bromine gas to produce hydrogen bromide gas. Hydrogen (g) + bromine (g) → hydrogen bromide (g) Hydrogen (g) + bromine (g) → hydrogen bromide (g)

6. Skeleton Equations Use the formulas for substances instead of their names Use the formulas for substances instead of their names Ex. Ex. Hydrogen (g) + bromine (g) → hydrogen bromide (g) Hydrogen (g) + bromine (g) → hydrogen bromide (g) H 2 (g) + Br 2 (g) → HBr (g) H 2 (g) + Br 2 (g) → HBr (g)