Happy New Year 2014! Happy New Year 2014!

Warm Up:

1. NaOH = _______________

2. MnO2 = _______________

3. Sodium sulfate = _______

4. Nitric acid = _____________

Ch. 8 Chemical Ch. 8 Chemical Equations and Equations and

ReactionsReactions8.1 Describing Chemical 8.1 Describing Chemical

ReactionsReactions

Chemical ReactionsChemical Reactions when a substance when a substance

changes identitychanges identity reactants- originalreactants- original products- resultingproducts- resulting

law of conservation of law of conservation of massmass total mass of total mass of

reactants = total mass reactants = total mass of productsof products

Chemical ReactionsChemical Reactions

chemical equationchemical equation represents identities and relative amounts of represents identities and relative amounts of

reactants and products in the chemical reactants and products in the chemical reactionreaction

uses symbols and formulas to represent uses symbols and formulas to represent chemicalschemicals

Uses coefficients to balance amountsUses coefficients to balance amounts

Hints of Chemical RxnHints of Chemical Rxn

heat or lightheat or light

gas bubblesgas bubbles

precipitateprecipitate

color changecolor change

Symbols Used in Symbols Used in EquationsEquations

yieldsyields

reversible reversible

above arrow:above arrow:

oror heat heat heatedheated

MnOMnO22 or or PtPt catalystcatalyst

25°C25°C specific T specific T requirementrequirement

2 atm2 atm specific P specific P requirementrequirement

after a formula:after a formula:

(s)(s) solidsolid

(l)(l)liquidliquid

(aq)(aq) aqueous: aqueous: dissolved dissolved

in in waterwater

(g)(g) gasgas

How to write How to write elements . . . elements . . .

most pure elements are most pure elements are written as elemental symbolwritten as elemental symbol

diatomic moleculesdiatomic molecules molecule containing only 2 molecule containing only 2

atomsatoms some elements normally exist some elements normally exist

this way (BrINClHOF twins)this way (BrINClHOF twins) HH22, O, O22, N, N22, F, F22, Cl, Cl22, Br, Br22, I, I22, At, At22

other exceptionsother exceptions sulfur: Ssulfur: S88

phosphorus: Pphosphorus: P44

Word EquationsWord Equations

uses names instead of formulasuses names instead of formulas

Can act as bridge between word problem Can act as bridge between word problem and actual chemical equationand actual chemical equation

ExampleExample

Solid sodium oxide is added to water Solid sodium oxide is added to water at room temperature and forms at room temperature and forms

sodium hydroxide.sodium hydroxide.

Another ExampleAnother Example

Ammonia is produced by reacting Ammonia is produced by reacting excess nitrogen with hydrogen.excess nitrogen with hydrogen.

Counting AtomsCounting Atoms

Use ElmoUse Elmo

Balancing EquationBalancing Equation

Use ElmoUse Elmo