Chemical Reaction Types

Reaction Types I Need to Know

Combustion Reactions Combustion means the reaction of oxygen with a compound usually containing carbon and hydrogen. A common synonym for combustion is Combustion means the reaction of oxygen with a compound usually containing carbon and hydrogen. A common synonym for combustion is

Combustion Reactions Written using generic symbols, it is usually shown as: Written using generic symbols, it is usually shown as: C x H y + O 2 ---> CO 2 + H 2 O These are some examples: CH 4 + O 2 ---> C 2 H 6 + O 2 ---> C 6 H 12 O 6 + O 2 ---> C 2 H 5 OH + O 2 --->

Combustion Notice that some compounds contain carbon, hydrogen AND oxygen. Notice that some compounds contain carbon, hydrogen AND oxygen. However, the products are all the same, in every reaction. Isn't that great? However, the products are all the same, in every reaction. Isn't that great?

Combustion Reactions How to figure out the product side: How to figure out the product side: (#1) Identify the reaction as combustion: (#1) Identify the reaction as combustion: A carbon-hydrogen compound reacting with oxygen A carbon-hydrogen compound reacting with oxygen (#2) Know that the combustion products are always CO 2 and H 2 O So the final answer looks like this: (#2) Know that the combustion products are always CO 2 and H 2 O So the final answer looks like this: C 7 H 6 O + O 2 ---> CO 2 + H 2 O THEN BALANCE!!!

CH 3 COCH 3 + O 2 --->

H 2 C 2 O 4 + O 2 --->

Synthesis Reactions Synthesis are almost always the reverse of a decomposition reaction. Synthesis are almost always the reverse of a decomposition reaction. That means that two pieces join together to produce one, more complex compound. That means that two pieces join together to produce one, more complex compound. These pieces can be elements or simpler compounds. These pieces can be elements or simpler compounds. Complex simply means that the product compound has more atoms than the reactant molecules. Complex simply means that the product compound has more atoms than the reactant molecules. Written using generic symbols, it is usually shown as: Written using generic symbols, it is usually shown as: A + B ---> AB

Synthesis Reactions These are some examples: These are some examples: Mg + O 2 ---> MgO H 2 + O 2 ---> H 2 O K + Cl 2 ---> KCl Fe + O 2 ---> Fe 2 O 3 Synthesis can also be two compounds making a more complex compound (or a compound and an element joining together) as in these examples: Synthesis can also be two compounds making a more complex compound (or a compound and an element joining together) as in these examples: CaO + CO 2 ---> CaCO 3 Na 2 O + CO 2 ---> Na 2 CO 3 KCl + O 2 ---> KClO 3 Ba(ClO 3 ) 2 ---> BaCl 2 + O 2

Decomposition Reactions During decomposition, one compound splits apart into two (or more pieces). These pieces can be elements or simpler compounds During decomposition, one compound splits apart into two (or more pieces). These pieces can be elements or simpler compounds Written using generic symbols, it is usually shown as: Written using generic symbols, it is usually shown as: AB ---> A + B

Decomposition Reactions AB ---> A + B However, that really only works for splitting apart into the elements, like these examples. However, that really only works for splitting apart into the elements, like these examples. HgO ---> Hg + O 2 H2O ---> H 2 + O 2 MgCl 2 ---> Mg + Cl 2 FeS ---> Fe + S

Decomposition Reactions Decomposition can also split one compound into two simpler compounds (or compound and an element) as in these examples: Decomposition can also split one compound into two simpler compounds (or compound and an element) as in these examples: CaCO 3 ---> CaO + CO 2 Na 2 CO 3 ---> Na 2 O + CO 2 KClO 3 ---> KCl + O 2 Ba(ClO 3 ) 2 ---> BaCl 2 + O 2 Notice how, in every case so far, there is only one substance on the left-hand (reactant) side. This is always the case in a decomposition reaction. Don't forget that!! Notice how, in every case so far, there is only one substance on the left-hand (reactant) side. This is always the case in a decomposition reaction. Don't forget that!!

ACTIVITY SERIES Appendix A of your Book p. 832 Appendix A of your Book p. 832 Most active one is at the top Most active one is at the top An element can displace those listed below it, but not above it An element can displace those listed below it, but not above it

How to Use the Activity Series p. 281 in your book Identify the reactants (metal or halogen) and if the element would be displaced Identify the reactants (metal or halogen) and if the element would be displaced Check the activity series Check the activity series Write the products Write the products Balance the equation Balance the equation

Single Replacement Reactions During single replacement, one element replaces another element in a compound. There are two different possibilities: During single replacement, one element replaces another element in a compound. There are two different possibilities: 1. One cation replaces another. 1. One cation replaces another. AX + Y ---> YX + A AX + Y ---> YX + A 2. One anion replaces another. 2. One anion replaces another. A + XY ---> XA + Y A + XY ---> XA + Y

Single Replacement Reactions 1. One cation replaces another. Written using generic symbols, it is: 1. One cation replaces another. Written using generic symbols, it is: AX + Y ---> YX + A Element Y has replaced A (in the compound AX) to form a new compound YX and the free element A. Element Y has replaced A (in the compound AX) to form a new compound YX and the free element A. Cu + AgNO 3 ---> Ag + Cu(NO 3 ) 2 Fe + Cu(NO 3 ) 2 ---> Fe(NO 3 ) 2 + Cu Ca + H 2 O ---> Ca(OH) 2 + H 2 Zn + HCl ---> ZnCl 2 + H 2

Single Replacement 2. One anion replaces another. Written using generic symbols, it is: 2. One anion replaces another. Written using generic symbols, it is: A + XY ---> XA + Y Element A has replaced Y (in the compound XY) to form a new compound XA and the free element Y. Element A has replaced Y (in the compound XY) to form a new compound XA and the free element Y. Remember that A and Y are both anions (negatively-charged ions) in this example. Remember that A and Y are both anions (negatively-charged ions) in this example. Cl 2 + NaBr ---> NaCl + Br 2 Br 2 + KI ---> KBr + I 2

Single Replacement In single replacement, one reactant is always an element. In single replacement, one reactant is always an element. Typically, you will be given the left-hand (reactant side) and asked to provide the products to the reaction. Typically, you will be given the left-hand (reactant side) and asked to provide the products to the reaction. You need to be able to recognize single replacement reactions AND be able to break a formula apart into proper cations and anions as well as write correct formulas You need to be able to recognize single replacement reactions AND be able to break a formula apart into proper cations and anions as well as write correct formulas

Practice Problems 1) ZnS + Fe ---> 1) ZnS + Fe ---> 2) K + H 2 O ---> 2) K + H 2 O ---> 3) Fe + HCl ---> 3) Fe + HCl ---> 4) NaI + Br 2 ---> 4) NaI + Br 2 --->

Double Replacement Reactions During double replacement, the cations and anions of two different compounds switch places. During double replacement, the cations and anions of two different compounds switch places. Written using generic symbols, it is: Written using generic symbols, it is: AB + XY ---> AY + XB A and X are the cations in this example, with B and Y being the anions A and X are the cations in this example, with B and Y being the anions

Double Replacement Examples KOH + H 2 SO 4 ---> FeS + HCl ---> NaCl + H 2 SO 4 ---> AgNO 3 + NaCl --->

p. 284 Identify Reactions and Predict Products Solubility Chart with Solubility Rules Solubility Chart with Solubility Rules

REMEMBER…. If you’re not part of the solution, you are part of the precipitate. ----Eric Desch