Types of Chemical Reactions

CH4(g) + 2O2(g)  CO2(g) + 2H2O(g) A. Combustion the burning of any substance in O2 to produce heat A + O2  B CH4(g) + 2O2(g)  CO2(g) + 2H2O(g)

A. Combustion C3H8(g)+ O2(g)  5 3 4 CO2(g)+ H2O(g) Products: contain oxygen hydrocarbons form CO2 + H2O C3H8(g)+ O2(g)  5 3 4 CO2(g)+ H2O(g)

B. Synthesis the combination of 2 or more substances to form a compound only one product A + B  AB

B. Synthesis H2(g) + Cl2(g)  2 HCl(g)

Al(s)+ Cl2(g)  2 3 2 AlCl3(s) B. Synthesis Products: ionic - cancel charges covalent - hard to tell Al(s)+ Cl2(g)  2 3 2 AlCl3(s)

Practice Predict the products. Write and balance the following synthesis reaction equations. Sodium metal reacts with chlorine gas Solid Magnesium reacts with fluorine gas Aluminum metal reacts with fluorine gas

C. Decomposition AB  A + B

a compound breaks down into 2 or more simpler substances only one reactant

C. Decomposition 2 H2O(l)  2 H2(g) + O2(g)

C. Decomposition 2 2 KBr(l)  K(s) + Br2(l) Products: binary - break into elements others - hard to tell 2 2 KBr(l)  K(s) + Br2(l)

A + BC  B + AC D. Single Replacement one element replaces another in a compound metal replaces metal (+) nonmetal replaces nonmetal (-) A + BC  B + AC

Cu(s) + 2AgNO3(aq)  Cu(NO3)2(aq) + 2Ag(s) D. Single Replacement Cu(s) + 2AgNO3(aq)  Cu(NO3)2(aq) + 2Ag(s)

D. Single Replacement Fe(s)+ CuSO4(aq)  Cu(s)+ FeSO4(aq) Products: metal  metal (+) nonmetal  nonmetal (-) free element must be more active (check activity series) Fe(s)+ CuSO4(aq)  Cu(s)+ FeSO4(aq) Br2(l)+ NaCl(aq)  N.R.

AB + CD  AD + CB E. Double Replacement ions in two compounds “change partners” cation of one compound combines with anion of the other AB + CD  AD + CB

Pb(NO3)2(aq) + K2CrO4(aq)  PbCrO4(s) + 2KNO3(aq) E. Double Replacement Pb(NO3)2(aq) + K2CrO4(aq)  PbCrO4(s) + 2KNO3(aq)

E. Double Replacement Pb(NO3)2(aq)+ KI(aq)  2 2 PbI2(s)+ KNO3(aq) Products: switch negative ions one product must be insoluble (check solubility table) Pb(NO3)2(aq)+ KI(aq)  2 2 PbI2(s)+ KNO3(aq) NaNO3(aq)+ KI(aq)  N.R.

one Two or more Yes No Are both reactants Ionic compounds? Is the element O2? No Yes Yes Are both reactancts single elements? Double Displacement Are the only elements present in the reactants side C, H, and O No No Yes No Yes Combustion Single Displacement Synthesis

No, Ni is below Na Yes, Li is above Zn Yes, Al is above Cu We have looked at several reactions: Fe + CuSO4  Cu + Fe2(SO4)3 Li + H2O  LiOH + H2 Such experiments reveal trends. The activity series ranks the relative reactivity of metals. It allows us to predict if certain chemicals will undergo single displacement reactions when mixed: metals near the top are most reactive and will displacing metals near the bottom. Q: Which of these will react? Fe + CuSO4  Ni + NaCl  Li + ZnCO3  Al + CuCl2  K Na Li Ca Mg Al Zn Fe Ni Sn Pb H Cu Hg Ag Au No, Ni is below Na Yes, Li is above Zn Yes, Al is above Cu Yes, Fe is above Cu Cu + Fe2(SO4)3 NR (no reaction) Zn + Li2CO3 Cu + AlCl3

A: No for cold, yes if it is hot/steam Mg + H2O  H2 + Mg(OH)2 acid H is the only nonmetal listed. H2 may be displaced from acids or can be given off when a metal reacts with H2O (producing H2 + metal hydroxide). The reaction with H2O depends on metal reactivity & water temp. Q: will Mg react with H2O? K Na Li Ca Mg Al Zn Fe Ni Sn Pb H Cu Hg Ag Au cold H2O hot H2O steam A: No for cold, yes if it is hot/steam Mg + H2O  H2 + Mg(OH)2 acid Q: Zn + HCl  H2 + ZnCl2 Complete these reactions: Al + H2O(steam)  Cu + H2O  Ca + H2SO4  Na + H2O  H2 + Al(OH)3 NR H2 + CaSO4 H2 + NaOH

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. On tests and exams the activity series may appear as K, Na, … Ag, Au; you must remember that K is reactive, Au is not. If the valence of a metal is not indicated in the question, use its most common valence (in bold on your periodic table) to determine the correct chemical formula.

Fluorine Chlorine Bromine Iodine

Even if everything is soluble, look for signs of a reaction H2SO4(aq) + 2NaOH(aq)  Na2SO(aq) + 2H2O(l) Heat is given off