Chapter 11.1Pages 321-324

Chemical ReactionsOccur everywhere and all the time

Rusting iron, Break down of glucose, Exploding hydrogen

Evidence of chemical reactionsColor change pH changeEnergy change (gets hotter or colder)

Precipitate formationGas formation

Chemical EquationsA representation of a chemical

reactionExample:

H2 + O2 2H2OReactants = H2 + O2 Products = 2H2O = Yields or Produces

Chemical Sentences and Word EquationsNames of elements or compounds are

used to indicate substances and the amounts used in a reaction

Example:H2 + O2 2H2O

Chemical SentenceOne molecule of hydrogen gas reacts

with one molecule of oxygen gas to produce (yield) two molecules of water.

Chemical Sentences and Word EquationsNames of elements or compounds are

used to indicate substances and the amounts used in a reaction

Example:H2 + O2 2H2O

Word EquationHydrogen gas + Oxygen gas Water

PracticeFe(s) + O2(g) Fe2O3(s)

What are the products?What are the reactants?What is the chemical sentence?What is the word equation?

H2O

Other Symbols to know…(s) = substance is in a solid state(l) = substance is in a liquid state

(aq) = aqueous solution - substance is dissolved in water

(g) = substance is in a gaseous state

Other Symbols to know…+ = used to separate two reactants or two products

= separates reactants from products

= for reversible reactions or = indicate that heat is used in the reaction

= A formula (could be any – in this case platinum) indicates it is used as a catalyst

Pt

Heat

CatalystA substance that speeds up a chemical reaction but is not used in the reaction

Example:Fe(s) + O2(g) Fe2O3(s)

What are the catalysts in this reaction?

What phase state is each substance in for this reaction?

H2O