Presentation on theme: "Reactions and Equations. Evidence of Chemical Reactions How can you tell a chemical reaction has taken place? – Temperature change – Color change – Odor."— Presentation transcript:
Evidence of Chemical Reactions How can you tell a chemical reaction has taken place? – Temperature change – Color change – Odor – Gas/bubbles – Appearance of a solid (precipitate)
Chemical Reaction A chemical reaction is the process by which atoms of one or more substances are rearranged to form different substances.
Reactant(s) and Product(s) Reactant(s) are the starting substance(s) of a reaction Product(s) are the substance(s) formed during the reaction means “react to produce” or “yield” Reactant(s) are on the left Product(s) are on the right
Representing Chemical Reactions reactant A+ reactant B product C + product D The plus sign separates each reactant or product (s) Identifies solid state (l) Identifies liquid state (g) Identifies gaseous state (aq) Identifies water solution (aqueous) Heat is applied to the reaction Example NH 4 NO 3 (s) N 2 O(g) + 2H 2 O(g)
Word Equation Uses words not chemical symbols to indicate the reactant(s) and product(s) of a chemical reaction. Example: iron(s) + chlorine(g) iron(III)chloride(s)
Skeleton Equation Skeleton equation uses formulas rather than words to identify the reactant(s) and product(s) Example Fe(s) + Cl 2 (g) FeCl 3 (s)
Balanced Chemical Equation The equation that shows the number of atoms of each reactant and each product is equal on both sides of the arrow is a balanced chemical equation Example 2Fe(s) + 3Cl 2 (g) 2FeCl 3 (s)