Chemical Reactions Chapter 11

How to Make a Cake 1. Add flour and eggs and milk, put in the oven for 20 minutes at 450 o F and you will have yourself a cake. 2. Flour (s) + eggs (s) + milk (l) → cake (s)

1.Word Equation: uses names of the reactants and products. Ex: aluminum plus copper (II) chloride yields aluminum chloride and copper REPLACE THE PLUS WITH A (+) AND THE YIELD WITH AN (  ) ALUMINUM + COPPER (II) CHLORIDE  ALUMINUM CHLORIDE + COPPER 2.Skeleton Equation: uses chemical symbols with no relative amounts. Ex: Al (s) + CuCl 2(aq) → AlCl 3(aq) + Cu (s)

NOTE!!!!!!! Make sure compounds are written properly. Remember to put up the charges and use criss-cross method if needed. *** Remember the diatomic molecules.

3. Phases: s - solid phase l - liquid phase g - gaseous phase aq – aqueous phase (exists in a water solution) EX: NaCl (aq) = solid NaCl dissolved in H 2 O

4.Balanced Formula Equation: shows the relative amounts of the atoms on each side of the equation. EX: 2Al (s) + 3CuCl 2(aq) → 2AlCl 3(aq) + 3Cu (s) LAW OF CONSERVATION OF MATTER To balance equations use ONLY coefficients. NEVER, NEVER change a subscript NOTE!!!!!!!

Balancing Reactions

Types of Reactions 1.Combination (Synthesis) 2.Decomposition 3.Single Replacement 4.Double Replacement 5.Combustion

1. Combination (Synthesis): Ex: A + B → AB Ex: 2H 2 + O 2 → 2H 2 O 2.Decomposition: Ex: AB → A + B Ex: 2H 2 O → 2H 2 + O 2 (electrolysis)

3.Single Replacement: Ex: A + BC → C + BA Ex: Zn + Cu(NO 3 ) 2 → ? Like replaces like USE ACTIVITY SERIES Is Zn higher than Cu on the list?

Activity Series of Metals Use for single replacement Reactions Li K Ba Sr Ca Na Mg Al Mn Zn Zn + Cu(NO 3 ) 2 → Zn(NO 3 ) 2 + Cu Fe Cd Co Ni Sn Pb H Cu Ag Hg Au Decreasing Activity

4.Double Replacement: Ex: AB + CD → AD + CB Ex: HCl + NaOH → H(OH) + NaCl 5.Combustion: Ex: hydrocarbon + O 2 → CO 2 + H 2 O Ex: CH 4 + 2O 2 → CO 2 + 2H 2 O This is an example of complete combustion.

These beakers contain 0.1 M solutions of silver nitrate, AgNO 3, and iron (III) chloride, FeCl 3. Since we can not see solid particles in these beakers we conclude that silver nitrate and iron (III) chloride are soluble in water. Let's check the conductivity of these solutions to be sure these salts form ions when they dissolve in water. AgNO 3 FeCl 3 Ionic Equations

To test for ions we will dip the two wires into a solution. If ions are present, the solution will conduct electricity and the bulb will light.

The wires that complete the electrical circuit to the light bulb have been dipped into a solution of FeCl 3. Does FeCl 3 form ions when it dissolves in water? YESNO

The wires that complete the electrical circuit to the light bulb have been dipped into a solution of FeCl 3. Right, when FeCl 3 dissolves in water it forms Fe +3 and Cl -1 ions. Next let's test silver nitrate.

The wires that complete the electrical circuit to the light bulb have been dipped into a solution of AgNO 3. Does AgNO 3 form ions when it dissolves in water? YESNO

The wires that complete the electrical circuit to the light bulb have been dipped into a solution of AgNO 3. Right, when AgNO 3 dissolves in water it forms Ag +1 and NO 3 -1 ions.

The conductivity experiments established that silver nitrate and iron (III) chloride form ions in aqueous solution. The ions conduct electricity so the bulb lights.

Let's mix the solution of AgNO 3 with the solution of FeCl 3. Mixing yields a white precipitate and a brown solution. What precipitated?

This is a double replacement rxn Either AgCl or Fe(NO 3 ) 3 formed the ppt See Table 11.3 on page 344

Fe(NO 3 ) 3 -Nitrate salts are soluble (dissolve and therefore don’t form precipitates) AgCl -THIS IS THE PPT

We now know the phases: AgNO 3(aq) + FeCl 3(aq) → AgCl (s) + Fe(NO 3 ) 3(aq) Let's look at the ions formed in the solutions. Not every ion formed is directly involved in the reaction.

We mixed a solution that contained Fe +3 and Cl -1 ions with one that contained Ag +1 and NO 3- ions.

AgNO 3(aq) + FeCl 3(aq) → AgCl (s) + Fe(NO 3 ) 3(aq) The Ag +1 and Cl -1 ions reacted to form the ppt, AgCl Are Fe 3+ & NO -3 directly Involved in the formation of AgCl?

Net Ionic Equations Shows what happens to the ions that take part in chemical reactions. Shows dissolved ionic compounds as their free ions. AgNO 3(aq) + FeCl 3(aq) → AgCl (s) + Fe(NO 3 ) 3(aq) 1 st BALANCE THE EQUATION: 3AgNO 3(aq) +FeCl 3(aq) → 3AgCl (s) +Fe(NO 3 ) 3(aq)

2 nd WRITE THE IONIC EQUATION: Only for aqueous solutions 3Ag + +3NO Fe +3 +3Cl - →3AgCl (s) +Fe +3 +3NO 3 -

3 rd CANCEL OUT THE SPECTATOR IONS: Ions that undergo no chemical change & aren’t directly involved during a chemical reaction. Appear on both sides of the chemical reaction. 3Ag + +3NO Fe +3 +3Cl - →3AgCl (s) +Fe +3 +3NO 3 - Cancel out all spectator ions

4 th WRITE THE NET IONIC EQUATION: Rewrite equation leaving out spectator ions. 3Ag + +3NO Fe +3 +3Cl - →3AgCl (s) +Fe +3 +3NO 3 - 3Ag + (aq) + 3Cl - (aq) → 3AgCl (s) Reduce coefficients Ag + (aq) + Cl - (aq) → AgCl (s) So, Fe +3 & NO 3 -1 weren’t directly involved in the formation of AgCl.

EX: Cl 2(g) + NaBr (aq) → Br 2(l) + NaCl (aq) 1 st : write ionic eq Cl 2(g) + Na + + Br - → Br 2(l) + Na + + Cl – 2 nd : cancel out spectator ions Cl 2(g) + Na + + Br - → Br 2(l) + Na + + Cl – 3 rd : write net ionic eq Cl 2(g) + Br - → Br 2(l) + Cl – 4 th : balance final net ionic eq Cl 2(g) + 2Br - → Br 2(l) + 2Cl –

Practice on Your Own Do question #32 a On page 344