2.  REACTANTS  PRODUCTS 1. Starting substances (reactants) becomes new substances (products).  2. Bonds are broken and new bonds are formed, but atoms are not created or destroyed (just rearranged).  Law of Conservation of Mass

3. PRODUCTSREACTANTS

4.  SENTENCE EQUATION Iron reacts with oxygen to produce rust  WORD EQUATION Iron + oxygen  iron (III) oxide  SKELETON EQUATION Fe + O 2  Fe 2 O 3  These DO NOT indicate the relative amounts of the reactants and products.

5.  BALANCED EQUATION ◦ most correct equation ◦ includes the physical states of each substance ◦ uses coefficients 4Fe(s) + 3O 2 (g)  2 Fe 2 O 3 (s) ◦ Learn chart of symbols on page 206 in text.

6. A) Skeleton equation B) Word equation C) Sentence equation D) Balanced equation

7. A) Skeleton equation B) Word equation C) Sentence equation D) Balanced equation

8.  Reactions are classified into five basic types. To be sure there are more than five types and many are combinations of these types. ◦ Combination (synthesis) (c) ◦ Decomposition (d) ◦ Single-Replacement (single displacement-sr) ◦ Double Replacement (double displacement-dr) ◦ Combustion (comb)  See page 222 -great summary of these types.

9.  Two or more substances combine to form a single substance  Basic equation ◦ A + B → AB ◦ If metal and non-metal, product is ionic ◦ If two non-metals, product is molecular

10.  A single compound is broken down into two or more products  Basic equation  AB →A + B  Produces a combination of elements and compounds. Products hard to predict.  Most require heat or light, or electricity

11.  Atoms of one element replace the atoms of another element (single displacement)  Basic equation  A + BC → AC + B if A is a metal  A + BC → BA + C if A a non-metal

12.  Involves the changing of positive ions between two compounds  Usually results in: ◦ Formation of precipitate ◦ Formation of a gas ◦ Formation of water  Basic equation  AB + CD →AD + CB

13.  A compound reacts with OXYGEN ( O 2 ) to produce energy in the form of heat and/or light.  When a compound containing carbon and hydrogen (called a hydrocarbon) burns in air the products are carbon dioxide and water. Called complete combustion ◦ CH 4 + 2O 2 → CO 2 + 2H 2 O

14.  Complete combustion assumes an ample supply of oxygen.  Incomplete combustion occurs with limited oxygen supply. Products of incomplete combustion are carbon monoxide and water. ◦ 2CH 4 + 3O 2 → 2CO+ 4H 2 O  Can also combust other non-metals or metals ◦ Recall burning magnesium

15.  A catalyst is used to speed up the rate of a chemical reaction but is NOT used up in the reaction. In bio, a catalyst is called an enzyme.

16. A) Synthesis B) Decomposition C) Single replacement D) Double replacement E) Combustion

17. A) Synthesis B) Decomposition C) Single replacement D) Double replacement E) Combustion

18.  Many reactions take place in aqueous systems (especially biological ones)  Can write various kinds of equations to describe these reactions ◦ Single replacement reactions ◦ Double replacement reactions

19.  A precipitate may form when two aqueous solutions are mixed.  Precipitate - a substance that falls out of solution when it is one of the products of a reaction. ◦ Precipitates are insoluble in water. ◦ The symbol for a precipitate is  in a word equation ◦ The symbol in a chemical equation (s) for solid

20.  No visible reaction (nvr) ◦ No insoluble substance formed  Formation of one ppt. ◦ Insoluble substance formed  Formation of two ppt. (rarely occurs) ◦ Two separate insoluble substances formed

21. Complete molecular equation AgNO 3 (aq) + KBr (aq) → KNO 3 (?) +AgBr (?) Does a ppt form? Use a solubility chart….

22. Complete molecular equation AgNO 3 (aq) + KBr (aq) → KNO 3 (?) +AgBr (?) Does a ppt form? Use a solubility chart….. AgNO 3 (aq) + KBr (aq) → KNO 3 (aq) +AgBr (s)

23. a. Why don’t Ag and K ions go together? b. Why don’t the bromide and nitrate ions go together? c. What determines if resultant formula written as AgBr or BrAg? OUTERS INNERS