Chapter 21 Chemical Reactions

Def: _______________ in which one or more substances are converted into _____________ substances _________________  Products “yield”

Conservation of Mass Antoine Lavoisier – _______s – Total ____________ of products always equals total mass of _________________ – Matter cannot be created or _________________ Father of _______________ Chemistry

Writing Equations Chemical Equation: ____________________ a chemical rxn using formulas and ______________

Unit Managers Coefficients: represent _______________ of units of each substance 2H 2 + O 2  2H 2 O coefficients

Writing Equations One unit of Nickel(II) chloride, dissolved in water, plus two units of sodium hydroxide, dissolved in water, produces one unit of solid nickel(II) hydroxide plus two units of sodium chloride, dissolved in water. __________________________________________

Chemical Rxns in the Environment Iron _________________ – Iron(III) Oxide – Very damaging Aluminum reacts with ____ – Aluminum Oxide – Coating, looks __________, protects _____________ reacts with air – Blue-green coating – ________________

Balancing Equations Section 2

Bicycle Equation 4 main parts to __________________ – Frame (F) – _______________ (W) – Handlebar (H) – _______________ (P)Bicycle FW 2 HP 2 F + W + H + P  FW 2 HP 2 F + __W + H + __P  FW 2 HP 2

Balanced Equations Balanced Equation: has _____________ # of atoms of each element on both sides of equation ___HgO(s)  ___Hg(l) + ___O 2 (g) _______________ atoms on each side Write in ___________________ Reduce if needed

Let’s Balance!! Fe(s) + Cl 2 (g)  FeCl 3 (s) MgSO 4 + KNO 3  Mg(NO 3 ) 2 + K 2 SO 4 Li(s) + H 2 O(l)  LiOH(aq) + H 2 (g)

Types of Reactions Section 3

Types of Reactions Organize all rxns into _______ main types – Combustion – _____________________ – Decomposition – Single Displacement – __________________________

Synthesis Rxns Def: two or more substances ______________ to form another A + B  ________ 1 ________________!! 2H 2 (g) + O 2 (g)  2H 2 O(g)

Combustion Rxns Type of synthesis - _________________ Def: substance reacts with _______________ to produce energy in the form of heat and light CH 4 (g) + 2O 2 (g)  _________(g) + 2H 2 O(g)

Decomposition Rxns __________________ of Synthesis Rxns Def: one substance ________________ down into two or more substances AB  ___________________ 1 ___________________!! 2H 2 O 2 (g)  2H 2 O (g) + O 2 (g) MnO 2

Single Displacement Def: one _____________________ replaces the other in a compound A + BC  ______________________ 1 element and 1 _____________________!! Cu(s) + 2AgNO 3 (aq)  Cu(NO 3 ) 2 (aq) + 2Ag(s)

Double Displacement Def: + ____________ of one compound replaces the + ion in another compound May form a ______________________ – an insoluble compound (doesn’t dissolve in H 2 O) AB + CD  ____________________ 2 ___________________ react!! Pb(NO 3 ) 2 (aq) + 2NaCl(aq)  PbCl 2 (s) + 2NaNO 3 (aq)

Chemical Rxns and Energy Section 4

Energy Exchanges All rxns ____________________ or absorb energy Energy could be heat, light, ______________, or electricity In rxns – bonds breaking – _________________ energy – bonds _________________ – releases energy

More Energy OUT Exergonic rxns – ______________ energy – ______________ energy needed to break bonds than released to form bonds Light or _____________ is given off Exothermic rxn – when energy given off is primarily ______________ – Feels ____________ Ex: burning wood, dynamite Provide most ___________________ to homes and industries

More Energy In Endergonic rxns: absorb, ___________, energy – Require _______________ energy to break bonds then to form bonds Electricity often _____________ energy to rxns Endothermic rxn: rxn absorbs __________ – Feels _____________

Catalysts and Inhibitors Catalyst: ______________ up a chemical rxn – __________________ change rxn, just makes it happen faster Inhibitors: ____________ down chemical rxn – Preservatives _________, BHA prevent spoilage rxn Don’t change amount _________________!!! Just speed or slow a rxn!!