TYPES OF TYPES OF CHEMICAL CHEMICAL REACTIONSREACTIONS

To react or not to react? THAT To react or not to react? THAT is the question!is the question!

Chemical changes are a result of Chemical changes are a result of chemical reactions. chemical reactions.

All chemical reactions involve a change All chemical reactions involve a change in substances and a change in energy. in substances and a change in energy.

Neither matter or energy is created Neither matter or energy is created or destroyed in a chemical reaction---or destroyed in a chemical reaction---only changed. only changed.

Synthesis ReactionSynthesis Reaction Decomposition ReactionDecomposition Reaction Single Displacement ReactionSingle Displacement Reaction Double Displacement ReactionDouble Displacement Reaction Activity Series of MetalsActivity Series of Metals

TYPES OF CHEMICAL REACTIONSTYPES OF CHEMICAL REACTIONS

SYNTHESIS REACTIONSYNTHESIS REACTION In a synthesis reaction two or more simple In a synthesis reaction two or more simple

substances combine to form a more substances combine to form a more complex substance. complex substance.

The reaction through the equation:The reaction through the equation: reactant + reactant -------> product reactant + reactant -------> product A + B -------> ABA + B -------> AB

For example, simple hydrogen gas For example, simple hydrogen gas combined with simple oxygen gas combined with simple oxygen gas can produce a more complex can produce a more complex substance—water!substance—water!

The chemical equation for this The chemical equation for this synthesis reaction is:synthesis reaction is: 2H 2H2 2 + O+ O22 2H 2H22OO

In the cartoon, the skinny bird (reactant) In the cartoon, the skinny bird (reactant) and the worm (reactant) combine to make and the worm (reactant) combine to make oneone product, a fat bird. product, a fat bird.

Some Types of Synthesis Some Types of Synthesis ReactionReaction

metal + oxygen metal + oxygen metal oxide metal oxide

4Fe4Fe(s)(s) + 3O + 3O2(g)2(g) 2Fe2Fe22OO3(s)3(s)

nonmetal + oxygen nonmetal + oxygen nonmetal nonmetal oxideoxide

SS(s)(s) + O + O2(g)2(g) SO SO2(g)2(g)

metal oxide + water metal oxide + water metallic hydroxide metallic hydroxide

MgOMgO(s)(s) + H + H22OO(l)(l) 2Mg(OH) 2Mg(OH)2(s)2(s)

nonmetallic oxide + water nonmetallic oxide + water acid acid

SOSO3(g)3(g) + H + H22OO(l)(l) H H22SOSO4(aq)4(aq)

metal + nonmetal metal + nonmetal salt salt

2Na2Na(s)(s) + Cl + Cl2(g)2(g) 2NaCl 2NaCl(s)(s)

Rusting of Iron

DECOMPOSITION REACTIONDECOMPOSITION REACTION

In a decomposition reaction a more In a decomposition reaction a more complex substance breaks down into complex substance breaks down into its more simple parts. its more simple parts.

One reactant yields 2 or more products. One reactant yields 2 or more products. Basically, synthesis and decomposition Basically, synthesis and decomposition reactions are opposites.reactions are opposites. reactant -------> product + product reactant -------> product + product

AB -------> A + BAB -------> A + B

For example, water can be broken For example, water can be broken down into hydrogen gas and oxygen down into hydrogen gas and oxygen gas. gas.

The chemical equation for this The chemical equation for this decomposition reaction looks like:decomposition reaction looks like:

2H2H22O O 2H 2H22 + O + O22

ExplosionsExplosions

The explosion of a dynamite is an The explosion of a dynamite is an example of a decomposition reaction. example of a decomposition reaction. When suitably activated, a highly When suitably activated, a highly exothermic reaction occurs in which exothermic reaction occurs in which large amounts of gaseous products form. large amounts of gaseous products form.

Nitroglycerin, which can be activated Nitroglycerin, which can be activated merely by shaking, decomposes as merely by shaking, decomposes as follows:follows:

4C4C33HH55(NO(NO33))3(l)3(l) 6N 6N2 (g)2 (g) + 12CO + 12CO2(g)2(g) + + 10H 10H2200(g)(g) + O + O2(g)2(g)

The egg (the reactant), which contained the The egg (the reactant), which contained the turtle at one time, now has opened and the turtle at one time, now has opened and the turtle (product) and egg shell (product) are turtle (product) and egg shell (product) are now two separate substances. now two separate substances.

Some Types of Some Types of Decomposition Reaction Decomposition Reaction

Metallic carbonates, when heated, Metallic carbonates, when heated, form metallic oxides and COform metallic oxides and CO2(g).2(g).

CaCOCaCO3(s)3(s) CaO CaO(s) (s) + CO+ CO2(g).2(g).

Most metallic hydroxides, when heated, Most metallic hydroxides, when heated, decompose into metal oxides and water.decompose into metal oxides and water.

Ca(OH)Ca(OH)2(s)2(s) CaO CaO(s) (s) + H+ H22OO(g).(g).

Some oxides, when heated, Some oxides, when heated, decompose. decompose.

2HgO2HgO(s) (s) 2Hg 2Hg(l) (l) + O+ O2(g)2(g) Some acids, when heated, decompose Some acids, when heated, decompose

into nonmetallic oxides and water. into nonmetallic oxides and water.

HH22SOSO4(s) 4(s) H H22OO(l) (l) + SO+ SO3(g)3(g)

SINGLE DISPLACEMENT SINGLE DISPLACEMENT REACTIONREACTION In a single displacement reaction a In a single displacement reaction a

single uncombined element replaces single uncombined element replaces another in a compound. another in a compound.

Two reactants yield two products. Two reactants yield two products.

reactant + reactant ---------> product + product reactant + reactant ---------> product + product

AB + C -------> AC + BAB + C -------> AC + B

For example when zinc combines For example when zinc combines with hydrochloric acid, the zinc with hydrochloric acid, the zinc replaces hydrogen. replaces hydrogen.

The chemical equation for this single The chemical equation for this single replacement reaction looks like:replacement reaction looks like:

Zn + 2HCl Zn + 2HCl ZnCl ZnCl22 + H + H22

Notice, the guy in the orange shirt steals Notice, the guy in the orange shirt steals the date of the other guy. So, a part of one the date of the other guy. So, a part of one of the reactants trades places and is in a of the reactants trades places and is in a different place among the products. different place among the products.

Some Types of Some Types of Single Displacement MethodSingle Displacement Method

Replacement of a metal in a Replacement of a metal in a compound by a more active metal.compound by a more active metal.

FeFe(s) (s) CuSO CuSO4(aq) 4(aq) + FeSO+ FeSO4(aq) 4(aq) + Cu+ Cu(s)(s)

Replacement of hydrogen in water by Replacement of hydrogen in water by an active metal.an active metal.

MgMg(s) (s) ++ HH22OO(aq) (aq) MgO MgO4(aq) 4(aq) HH2(g)2(g)

Replacement of hydrogen in acids by Replacement of hydrogen in acids by active metals.active metals.

ZnZn(s) (s) ++ 2HCl2HCl(aq) (aq) ZnCl ZnCl2(aq) 2(aq) + H+ H2(g)2(g)

Replacement of nonmetal by a more Replacement of nonmetal by a more active nonmetal.active nonmetal.

ClCl2(g) 2(g) + 2NaBr+ 2NaBr(aq) (aq) 2NaCl 2NaCl(aq) (aq) + Br+ Br2(g)2(g)

DOUBLE REPLACEMENT DOUBLE REPLACEMENT REACTIONREACTION In a double displacement reaction In a double displacement reaction

parts of two compounds switch parts of two compounds switch places to form two new compounds. places to form two new compounds.

Two reactants yield two products. Two reactants yield two products.

reactant + reactant ---------> product + product reactant + reactant ---------> product + product

AB + CDAB + CD -------> AC + BD-------> AC + BD

For example when silver nitrate For example when silver nitrate combines with sodium chloride, two combines with sodium chloride, two new compounds--silver chloride and new compounds--silver chloride and sodium nitrate are formed because sodium nitrate are formed because the sodium and silver switched places. the sodium and silver switched places.

The chemical equation for this double The chemical equation for this double replacement reaction looks like:replacement reaction looks like:

AgNOAgNO3 3 + NaCl + NaCl AgCl + NaNO AgCl + NaNO33

Why do you take a tablet when you Why do you take a tablet when you have an upset stomach?have an upset stomach?

Calcium carbonate reacts with the Calcium carbonate reacts with the hydrochloric acid in your stomach. hydrochloric acid in your stomach. This is shown in this equation:This is shown in this equation:

CaCOCaCO33 + 2HCl + 2HCl CaCl CaCl22 + H + H22COCO33

Metal Activity SeriesMetal Activity Series Metal Metal Ion Reactivity

Lithium Potassium Calcium Sodium Magnesium Aluminum Manganese Zinc Chromium Iron Lead Copper Mercury Silver Platinum Gold

Li+ K+ Ca2+ Na+ Mg2+ Al3+ Mn2+ Zn2+ Cr2+, Cr3+ Fe2+, Fe3+ Pb2+ Cu2+ Hg2+ Ag+ Pt2+ Au+, Au3+

Most Reactive - - - - - - - - - - - - - - Least Reactive

A metal can replace metals listed below it in A metal can replace metals listed below it in the activity series, but not above. For the activity series, but not above. For example, sodium is highly active and thus example, sodium is highly active and thus able to replace hydrogen from water:able to replace hydrogen from water:

– 2 Na (s) + 2 H2 Na (s) + 2 H22O (l) → 2 O (l) → 2 NaOH (aq) + H (aq) + H22 (g) (g)

The reactivity series determines qualitatively The reactivity series determines qualitatively characteristics such as the reactions with characteristics such as the reactions with water, air and acids as demonstrated above. water, air and acids as demonstrated above. However it is defined by the nature of the However it is defined by the nature of the metals in single displacement reactions.metals in single displacement reactions.

When a metal in elemental form is placed in When a metal in elemental form is placed in a solution of a metal salt it may be, overall, a solution of a metal salt it may be, overall, more energetically feasible for this more energetically feasible for this "elemental metal" to exist as an ion and the "elemental metal" to exist as an ion and the "ionic metal" to exist as the element. "ionic metal" to exist as the element. Therefore the elemental metal will 'displace' Therefore the elemental metal will 'displace' the ionic metal over time, thus the two swap the ionic metal over time, thus the two swap places. Only a metal higher in the reactivity places. Only a metal higher in the reactivity series will displace another.series will displace another.