Chemical reactions  Remember indications of a chemical change  energy change  Color change  Precipitate formed  Gas given off

What is energy?  Anything that is not matter and can cause a change in matter  Examples:  Heat  Sound  light

Symbols to know  yields or reacts to form +plus or and (s)solid (l)liquid (g)gas (aq)dissolved in water catalyst is written on yields sign Heat is a triangle on yields sign

Remember  Ionic compounds are usually solids (s) (but they can be dissolved in water)  All acids are dissolved in water (aq)  Metals are solid except Hg  Br 2 is a liquid

Magnesium metal and sodium chloride dissolved in water react to form magnesium chloride dissolved in water and sodium metal

Try these!  Solid magnesium reacts with oxygen in the air to form solid magnesium oxide.  Bubbles of hydrogen gas and aqueous zinc sulfate are produced when zinc metal is added to sulfuric acid

Diatomic molecules H 2 N 2 O 2 F 2 Cl 2 Br 2 I 2

matter cannot be created nor destroyed (its conserved). number of atoms reacted equals  number of atoms reacted equals number of atoms produced number of atoms produced take an atom inventory  take an atom inventory Law of Conservation of Matter

Rules for Balancing Equations 1.Write reactants on left, products on right products on right 2Write correct formulas 3.Take an atom inventory 4. Balance the number of atoms by placing a coefficient in front of the formula (DON’T CHANGE SUBSCRIPTS) 5.Repeat until all atoms are balanced 6.Put coefficients in lowest terms

Practice  Balance and write the words: Br 2(l) + NaI (aq)  NaBr (aq) + I 2(s) Al (s) +CuSO 4 (aq)  Al 2 (SO 4 ) 3(aq) +Cu (s)

Practice  Mercury metal is produced by heating a mixture of mercury(II)sulfide and calcium oxide. Other products are calcium sulfide and calcium sulfate.

Types of Chemical reactions  Combination(synthesis) A + B  AB  Decomposition AB  A + B  Single replacement A + BX  AX + B  Double Replacement AX + BY  AY + BX  Combustion H x C y + O 2  CO 2 + H 2 O

Combination(synthesis) Mg + O 2  MgO Sodium and chlorine react to form Iron and oxygen react to form iron (III) product

Decomposition H 2 O 2  H 2 O + O 2 Water decomposes with electricity Into its elements Calcium carbonate decomposes to form calcium oxide and carbon dioxide

Hydrogen H+ Tin Sn +2,Sn + 4

Single replacement Mg + HCl  MgCl 2 + H 2 look up on activity series(p106) Mg must be higher than H for a reaction Mg + KCl  No reaction Mg is lower than K so “ no go”

Activity Series and History  What were some of the first metals used by man?  Copper –4000 BC  Why?  What age came next?  Bronze age 3 – 2000 BC (Trojan war)  What is bronze?  What age came next?  Iron Age 1000 BC on

Why Bother Discussing This?  Locate copper, tin and iron  Copper is found in metallic form  It is an uncombined element  Look below copper, gold, mercury and silver  “coinage” metals  Tin is easy to turn into its elemental form  Iron requires lots of energy! Li K Ba Sr Ca Na Mg Al Mn Zn Fe Cd Co Ni Sn Pb H Cu Ag Hg Au

Ionic Compounds  When an ionic compound dissolves in water, what actually happens?

The battle between water and “columbic” attraction Particles of opposite charge are attracted to each other. This attraction is called columbic attraction

Ionic Solution  So an ionic solution is really a bunch of charged particles floating around  Water “hydrates” or surrounds each particle  Water keeps the Plus and minus charges from attracting each other  If the plus and minus are more attracted to each other than to the water, then they combine and make a precipitate - it is not soluble

Double Replacement  Metal ions replace each other  All reactants are aqueous  Check products on solubility table to see if solid or aqueous MgSO 4 + NaCl  BaSO 4 + Ag 2 CO 3 

Combustion  Complete hydrocarbon + O 2  CO 2 + H 2 O C 5 H 10 + O 2  CO 2 + H 2 O  Incomplete Hydrocarbon + O 2  CO + H 2 O C + H 2 O

Practice  Balance and write the words: Br 2(l) + NaI (aq)  NaBr (aq) + I 2(s) Al (s) +CuSO 4 (aq)  Al 2 (SO 4 ) 3(aq) +Cu (s)

Practice  Balance and write the words: Br 2(l) + NaI (aq)  NaBr (aq) + I 2(s) Al (s) +CuSO 4 (aq)  Al 2 (SO 4 ) 3(aq) +Cu (s)

Practice  Balance and write the words: Br 2(l) + NaI (aq)  NaBr (aq) + I 2(s) Al (s) +CuSO 4 (aq)  Al 2 (SO 4 ) 3(aq) +Cu (s)

C + O 2  CO 2 C-1 O-2 C- 1 O – 2 O – 2