CP Chapter 11 Notes Reactions and Equations

Transcription

1 CP Chapter 11 Notes Reactions and Equations Evidence of Chemical Reactions How can you tell a reaction has taken place? Temperature change Color change Gas/bubbles Appearance of a (precipitate) Chemical Reaction A chemical reaction is the process by which atoms of one or more substances are to form substances. What are the signs that a chemical reaction has taken place? What is a chemical reaction? Reactant(s) and Product(s) Reactant(s) are the substance(s) of a reaction Product(s) are the substance(s) formed the reaction means react to produce or yield Reactant(s) are on the left Product(s) are on the Representing Chemical Reactions reactant A reactant B product C product D The plus sign each reactant or product (s) Identifies solid state (l) Identifies state (g) Identifies gaseous state (aq) Identifies solution - is applied to the reaction Example NH 4 NO 3 (s) N 2 O(g) 2H 2 O(g) What are reactants? What are products? What does mean in a chemical reaction? Where are the reactants located in a written chemical reaction? Where are the products located in a written chemical reaction? Word Equation Uses not chemical symbols to indicate the (s) and product(s) of a chemical reaction. Example iron(s) chlorine(g) iron(iii) (s) Skeleton Equation Skeleton equation uses rather than words to identify the reactant(s) and product(s) Example (s) Cl 2 (g) FeCl 3 (s) 1

2 Balanced Chemical Equation The equation that shows the of atoms of each reactant and each product is on both sides of the arrow is a chemical equation Example 2Fe(s) 3Cl 2 (g) 2FeCl 3 (s) What is a word equation? What is a skeleton equation? What is a balanced chemical equation? Balancing Equations Step 1 Write the equation. Step 2 Balance each element by placing in front of the chemical formulas. Balance in this order: metals non-metals hydrogen oxygen Step 3 Select coefficients that will give the number of atoms on each side of the equation. If you have an number of oxygen atoms, multiply the coefficient by first to make it an even number. Then try to balance the equation. Step 4 Check all other elements to see whether the equation is. Other elements may have become unbalanced. Make to balance all the elements. Step 5 If it becomes difficult to balance an equation, use a as a coefficient then to get rid of the fraction. Balance these equations. 1. HgO Hg O 2 2. Mg O 2 MgO 3. KClO 3 KCl O 2 4. AgNO 3 H 2 S Ag 2 S HNO 3 5. Al(OH) 3 H 2 SO 4 Al 2 (SO 4 ) 3 H 2 O 6. Zn(OH) 2 H 3 PO 4 Zn 3 (PO 4 ) 2 H 2 O 7. FeCl 3 NaOH Fe(OH) 3 NaCl 2

3 Types of Reactions Five Types of Reactions There are different types of reactions Synthesis/Combination Reaction Reaction Decomposition Reaction Single-replacement Reaction Double- Reaction Synthesis/Combination Reaction AB 2Fe(s) 3Cl 2 (g) 2FeCl 3 (s) CaO(s) H 2 O(l) Ca(OH) 2 (s) Two or more substances react to produce a product To tell if it is a synthesis/combination reaction, one product is formed from two or more Combustion Reaction In a combustion reaction combines with a substance and energy. Oxygen (O 2 ) is a in a combustion reaction Example: 2H 2 (g) O 2 (g) 2H 2 O(g) In the combustion of a hydrocarbon (molecule with just hydrogen and carbon) and carbon dioxide are produced Ex: CH 4 (g) O 2 (g) CO 2 (g) H 2 O(g) How can you tell if there is a synthesis/combination reaction? How can you tell if there is a combustion reaction? Determine if the reaction is synthesis/combination or combustion 2Na Cl 2 2NaCl C(s) O 2 (g) CO 2 (g) Decomposition Reaction In a decomposition reaction a compound breaks down into two or more elements or compounds AB A B 2NaN 3 (s) 2Na(s) 3N 2 (g) One reactant breaks up into two or more. To tell if it is a decomposition reaction, there is only one reactant forming two or more products Single Replacement Reactions Single replacement reactions are when atoms of one element the atoms of another element in a compound. A BX AX B 2Li(s) 2H 2 O(l) 2LiOH(aq) H 2 (g) To tell if it is a single replacement reaction, a, H 2 or a halogen is by itself. Like a boyfriend thief 3

4 Double Replacement Reactions A double replacement reaction is when there is an of ions between compounds. AX BY AY BX Ca(OH) 2 (aq) 2HCl(aq) CaCl 2 (aq) 2H 2 O(l) To tell if it is a double replacement reaction, there are two compounds reacting with each other forming two compounds How can you tell if there is a decomposition reaction? What is a single replacement reaction and how can you tell if there is one? What is a double replacement reaction and how can you tell if there is one? Single Replacement Reactions Single Replacement Reaction: A BX Metals will replace or Halogens will replace If an ion can take on two different charges, we will use the charge for this worksheet. Metals H 2 O H 2 OH You must use the Activity Series Chart to find out if the reaction takes place. For each reaction use the activity series to complete the reaction. If no reaction will occur, write no reaction. Make sure to balance your final answer. 1. Zn AgNO 3 2. Cl 2 KI 3. Ag KNO 3 4. Mg HCl 5. Fe CuSO 4 6. Al CuSO 4 7. Br 2 CaI 2 8. Mg H 2 SO 4 9. Cu H 2 O 10. Fe AgC 2 H 3 O 2 Most reactive Least reactive Activity Series Metals Non-metals Li F2 Rb Cl2 K Br2 Cs I2 Ba Sr Ca Na Mg Al Ti Mn Zn Cr Fe Cd Co Ni Sn Pb H Sb Bi Cu Hg Ag Pt Au 4

5 Double Replacement Reactions AY BX AX BY DR Reactions Equation: One of Three things happens in a DR Reaction: 1. (s) 2. (l) Or (aq) 3. (g) If both products are then there will be no. Use the Solubility Chart to predict if a substance is or in. 1. Na 3 PO 4 4. Fe(OH) 3 2. PbBr 2 5. AlCl 3 3. CaCl 2 6. NaCl Complete and balance the equations for the following double-replacement reactions. Write (s) next to the product that is in, (aq) next to the product that is, or (l) next to water. If no reaction takes place write NR. 1. AgNO 3 (aq) NaCl(aq) 2. Mg(NO 3 ) 2 (aq) KOH(aq) 3. NaNO 3 (aq) K 3 PO 4 (aq) 4. HI(aq) Li 2 S(aq) 5. AgNO 3 (aq) KCl(aq) 6. HCl(aq) Na 2 CO 3 (aq) 7. H 2 SO 4 (aq) Mg(OH) 2 (aq) 8. KCN(aq) HBr(aq) 5

6 Activity Series Metals Nonmetals Li Most Reactive F 2 Rb Cl 2 K Br 2 Cs I 2 Ba Sr Ca Na Mg Al Ti Zn Cr Fe Ni Sn Pb *H Cu Ag Pd Hg Pt Au Least Reactive NEGATIVE ION (ANION) PLUS SOLUBILITY CHART POSITIVE ION (CATION) FORMS A COMPOUND WHICH IS: any negative ion alkali metal ions any negative ion ammonium (NH 4 ) nitrate (NO - 3 ) any positive ion acetate (C 2 H 3 O - 2 ) any positive ion except Ag or Hg chloride (Cl - ), Ag, Pb 2, Hg, or Cu bromide (Br - ), or iodide (I - ) sulfate (SO 4-2 ) Ca 2, Sr 2, Ba 2, Ra 2, Ag, or Pb 2 not not sulfide (S -2 ) hydroxide (OH - ) alkali metal ions, NH 4, Be 2, Mg 2, Ca 2, Sr 2, Ba 2, or Ra 2 alkali metal ions or NH 4 not phosphate (PO 4-3 ), carbonate (CO 3-2 ), or sulfite (SO 3-2 ) alkali metal ions or NH 4 not not 6