Steps to Predicting the Products of Chemical Reactions Honors Chemistry

Once you classify the reaction, then write the products. If it is combustion, then just write H2O and CO2 as products. If it is synthesis, write a compound that contains both elements. (remember to balance the charges for ionic compounds) If it is decomposition, then attempt to break it into two elements or compounds.

If it is double replacement, then the cation and anions switch places. If it is single replacement, then replace the single element with the corresponding element in the compound.   A metal will replace the cation in the compound A non-metal will replace the anion in the compound Remember to take into account the charges on the cation and anion and write the formula correctly! If it is double replacement, then the cation and anions switch places. It is helpful to separate each compound into their cation and anionic parts with their charges. Then switch places, and criss cross the new compounds to make sure they are the correct neutral compound formulas.

Diatomics! Remember the elements that exist in diatomic form. H, N, O, F, Cl, Br and I All exist with two of the element: H2 N2 O2 F2 Cl2 , Br2 , I2

A + B  Synthesis/Combination Example: Na(s) + Cl2(g)  2 elements indicates synthesis Write Charges for each then write compound Na+ Cl- NaCl (balance the charges on the ionic compound) Balance the Reaction 2 2 NaCl

AB  Decomposition A single reactant indicates a decomposition reaction. Separate compound into elements (remember diatomics) or less complex compounds (we will be memorizing some of these later!) Examples: MgO  Ca(OH)2  Mg + O2 2 2 CaO + H2O

Predicting Products of Synthesis and Decomposition Rules Metal chlorates break down into metal chlorides and oxygen. Ex: 2 NaClO3  2 NaCl + 3 O2 Metal oxides react with water to produce metal hydroxides Ex: K2O + H2O  2 KOH Metal carbonates break down into metal oxides and carbon dioxide Ex: CaCO3  CaO + CO2 Metal hydroxides break down into metal oxides and water. Ex: Mg(OH)2  MgO + H2O

CLASSWORK Complete the worksheet called, “Synthesis and Decomposition Reactions.

AB + C  Single Displacement AB is an ionic compound and C is an element. If element is a metal, it replaces the cation. CuSO4 + Zn  If element is a non-metal, it replaces the anion. LiI + F2  Remember correct charges and diatomics! Then balance at the end. Cu + ZnSO4 2 I2 + LiF 2

Predicting Single Replacement Reactions The Activity Series Predicting Single Replacement Reactions

THE ACTIVITY SERIES Not every single-replacement reaction will happen. The element on the reactant side must be more “active” than the one it could replace. Scientists have listed the order of activity of elements in THE ACTIVITY SERIES.

Let’s look at several reactions: Fe + CuSO4  Cu + Fe2(SO4)3 Na Li Ca Mg Al Zn Fe Ni Sn Pb H Cu Hg Ag Au Yes, Fe is above Cu Let’s look at several reactions: Fe + CuSO4  Cu + Fe2(SO4)3 Li + ZnCO3  Li2CO3 + Zn The activity series ranks the relative reactivity of metals. It allows us to predict if certain chemicals will undergo single replacement reactions when mixed: metals near the top are most reactive and will replace metals near the bottom. Q: Which of these will react? Ni + NaCl  Al + CuCl2  Yes, Li is above Zn No, Ni is below Na NR (no reaction) Cu + AlCl3 Yes, Al is above Cu

Other Activity Series Information All metals will have a specific place in the activity series. For simplicity, only the most common metals are shown. The metals near the top of the activity series are more reactive because their valence electrons are more easily removed.

There is also an activity series for the Halogens: No, I2 is below Cl2 There is also an activity series for the Halogens: The activity series ranks the relative reactivity of Non-Metals. Q: Which of these will react? I2 + 2NaCl  F2 + 2NaBr  F2 Cl2 Br2 I2 NR (no reaction) Br2 + 2NaCl Yes, F2 is above Br2

AB + CD  Double Displacement AB and CD are both ionic compounds. Separate each compound & write their charges. Switch places and re-write new compounds. Example: Pb(NO3)2 + KI  Pb2+ NO3- K+ I- Pb2+ I- K+ NO3- Balance at the end 2 PbI2 + KNO3 2

CxHy + O2  Combustion Can also be CxHyOz A hydrocarbon and oxygen indicate a combustion reaction. Just write CO2 and H2O as products and then balance (this is the hard part!) C4H10 + O2  CO2 + H2O

CLASSWORK COMPLETE 8.3 Wksht