UNIT 7 CHEMICAL REACTIONS INTRO TO REACTIONS CHEMICAL

CHEMICAL VS. PHYSICAL CHANGES CHEMICAL PHYSICAL n Color change n Change in: n Gas

CHEMICAL VS. PHYSICAL CHANGES CHEMICAL n Color change n Gas production n Precipitate forms

VOCABULARY n. EXERGONIC: reaction that releases energy n. ENDERGONI C: reaction that absorbs energy

VOCABULARY n EXOTHERMIC: reaction that releases energy as heat n ENDOTHERMIC : reaction that

Coefficient n. A small whole number placed in front of a compound in a

Chemical Equations + + REACTANTS PRODUCTS Before After

Chemical Equations 2 H 2 (g) + O 2 (g) 2 H 2 O

SYMBOLS in Chemical Equations + Plus, and Produces, forms, yields (s) solid (l) liquid

Chemical Equations 2 Al(s) + 3 Cu. Cl 2(aq) 3 Cu(s) + 2 Al.

Writing Equations 2 H 2(g) + O 2(g) 2 H 2 O(g) n Identify

Writing Equations Two atoms of solid aluminum react with three units of aqueous copper(II)

Describing Equations Describing Coefficients: ·individual atom = “atom” ·covalent substance = “molecule” ·ionic substance

Describing Equations Zn(s) + 2 HCl(aq) Zn. Cl 2(aq) + H 2(g) • How

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UNIT 7 -CHEMICAL REACTIONS: INTRO TO REACTIONS

CHEMICAL VS. PHYSICAL CHANGES CHEMICAL PHYSICAL n Color change n Change in: n Gas ·Size production ·Shape n Precipitate ·State of forms matter n Light/heat is produced

CHEMICAL VS. PHYSICAL CHANGES CHEMICAL n Color change n Gas production n Precipitate forms n Light/heat is produced SIGNS OF CHEMICAL REACTION S!

VOCABULARY n. EXERGONIC: reaction that releases energy n. ENDERGONI C: reaction that absorbs energy

VOCABULARY n EXOTHERMIC: reaction that releases energy as heat n ENDOTHERMIC : reaction that absorbs energy as heat

Coefficient n. A small whole number placed in front of a compound in a chemical reaction that multiplies its quantity. 2 H 2 O = two water molecules

Chemical Equations + + REACTANTS PRODUCTS Before After

Chemical Equations 2 H 2 (g) + O 2 (g) 2 H 2 O (l) 2 H and O 2 2 REACTANTS: ______ 2 H O 2 PRODUCTS: _______

SYMBOLS in Chemical Equations + Plus, and Produces, forms, yields (s) solid (l) liquid (g) gas (aq) Aqueous (solid in water)

Chemical Equations 2 Al(s) + 3 Cu. Cl 2(aq) 3 Cu(s) + 2 Al. Cl 3(aq) Al = solid Cu. Cl 2 = aqueous Cu = solid Al. Cl 3 = aqueous

Writing Equations 2 H 2(g) + O 2(g) 2 H 2 O(g) n Identify the substances involved. n Use symbols to show: ·How many? - coefficient ·Of what? - chemical formula ·In what state? - physical state n Remember the diatomic elements.

Writing Equations Two atoms of solid aluminum react with three units of aqueous copper(II) chloride to produce three atoms of solid copper and two units of aqueous • How many? aluminum chloride. • Of what? • In what state? 2 Al(s)+ 3 Cu. Cl 2 (aq) 3 Cu (s) + 2 Al. Cl 3 (aq)

Describing Equations Describing Coefficients: ·individual atom = “atom” ·covalent substance = “molecule” ·ionic substance = “unit” 3 CO 2 3 molecules of carbon dioxide 2 Mg 2 atoms of magnesium 4 Mg. O 4 units of magnesium oxide

Describing Equations Zn(s) + 2 HCl(aq) Zn. Cl 2(aq) + H 2(g) • How many? Of what? In what state? One atom of solid zinc reacts with two molecules of aqueous hydrochloric acid to produce one unit of aqueous zinc chloride and one molecule of hydrogen gas.