2 Types of ReactionsThere are six types of chemical reactions that we learn about in Chemistry:Synthesis or composition reactionsDecomposition reactionsSingle displacement (a.k.a. replacement)Double displacement (a.k.a. replacement)CombustionAcid-BaseYou will need to be able to identify the type of reaction and predict the product(s)
3 The “Diatomic 7” are: Hydrogen, H2 Things to know:Some elements are found bonded to themselves- like identical twins. These are called diatomic molecules.The “Diatomic 7” are: Hydrogen, H2Nitrogen, N2Oxygen, O2Fluorine, F2Chlorine, Cl2Bromine, Br2Iodine, I2
4 The diatomic 7 make a “7” starting at element #7, plus H
5 Things to Remember:Follow the ‘rules’ of bonding when writing compounds or moleculesFor example:How does Sodium bond with Chlorine?Na+1 Cl-1 so it will be: NaClH+1 will bond with O-2 as H2OYou may be tempted to write compounds and molecules differently to balance an equation- but you can’t! They bond as they bond.
6 Steps for Writing Reactions Some steps for writing chemical reactionsIdentify the type of reactionPredict the product(s) using the type of reactionBalance the equationDon’t forget about the diatomic elements! (big 7) For example, Oxygen when by itself is O2 as a diatomic element; it is not found as just O.In a compound or molecule, it can’t be a diatomic element because it’s not an element anymore, it’s a compound or molecule!
7 Synthesis ReactionsHere is an example of a synthesis reaction
8 PracticePredict the products: Write and balance the following synthesis reaction equations.Sodium metal reacts with chlorine gasNa(s) + Cl2(g) Solid Magnesium reacts with fluorine gasMg(s) + F2(g) Aluminum metal reacts with fluorine gasAl(s) + F2(g)
9 Decomposition Reactions An example of a decomposition reaction:
10 Decomposition Exceptions Carbonates and chlorates are special case decomposition reactions that do not go to the elements.Carbonates (CO32-) decompose to carbon dioxide and a metal oxideExample: CaCO3 CO2 + CaOChlorates (ClO3-) decompose to oxygen gas and a metal chlorideExample: 2 Al(ClO3)3 2 AlCl3 + 9 O2There are other special cases, but we will not explore those in Chemistry I
11 PracticePredict the products: Then, write and balance the following decomposition reaction equations:Solid Lead (IV) oxide decomposes PbO2(s) Aluminum nitride decomposesAlN(s)
12 Practice N2(g) + O2(g) BaCO3(s) Co(s)+ S(s) Nitrogen monoxide Identify the type of reaction for each of the following synthesis or decomposition reactions, and write the balanced equation:N2(g) + O2(g) BaCO3(s) Co(s)+ S(s) NH3(g) + H2CO3(aq) NI3(s) Nitrogen monoxide(make Co be +3)
14 Single Replacement Reactions Write and balance the following single replacement reaction equation:Zinc metal reacts with aqueous hydrochloric acidZn(s) HCl(aq) Note: Zinc replaces the hydrogen ion in the reaction… Why?
15 Single Replacement Reactions Sodium chloride solid reacts with fluorine gas__NaCl(s) + __F2(g) __NaF(s) +__Cl2(g)Note that fluorine replaces chlorine in the compoundAluminum metal reacts with aqueous copper (II) nitrateAl(s)+ Cu(NO3)2(aq)
16 Double Replacement Reactions Think about it like “foil”ing in algebra, the first and last ions go together and the inside ions go togetherExample:AgNO3(aq) + NaCl(s) AgCl(s) + NaNO3(aq)Another example:K2SO4(aq) + Ba(NO3)2(aq)
17 Practice Predict the products. Balance the equation HCl(aq) + AgNO3(aq) CaCl2(aq) + Na3PO4(aq) Pb(NO3)2(aq) + BaCl2(aq) FeCl3(aq) + NaOH(aq) H2SO4(aq) + NaOH(aq) KOH(aq) + CuSO4(aq)
18 Combustion ReactionsCombustion reactions occur when a hydrocarbon reacts with oxygen gas.This is also called burning!!! In order to burn something you need the 3 things in the “fire triangle”: 1) A Fuel (hydrocarbon) 2) Oxygen to burn it with 3) Something to ignite the reaction (spark)
19 CombustionExampleC5H O2 CO2 + H2OWrite the products and balance the following combustion reaction:C10H O2 856
20 Mixed PracticeState the type, predict the products, and balance the following reactions:BaCl2 + H2SO4 C6H12 + O2 Zn + CuSO4 Cs + Br2 FeCO3