Types of Chemical Reactions



Types of Chemical Reactions

Tutorial

There are five general types of chemical reactions.

Combination (Synthesis) Reactions

Combination reactions are reactions in which two or more reactants combine for form a single product. They follow the general format of

A + B → C

For example: 2Na + Cl2 → 2NaCl

Combustion Reactions

Combustion reactions are reactions in which a substance reacts with oxygen gas to produce heat and light. Oxygen is always a reactant in combustion reactions.

Example: CH4 + 2O2 → CO2 + 2H2O

Decomposition Reactions

Decomposition Reactions are reactions in which a substance breaks down into two or more smaller substances. They follow the general format of

A → B + C

For example: 2 HgO (s) → 2 Hg(l) + O2 (g)

Single Replacement Reactions

Single replacement reactions (sometimes called single displacement reactions) are reactions in which an element replaces another atom or ion in a compound. They follow the general format of

A + BC → AC + B

For example: 2 Al (s) + 3 CuCl2 (aq) → 2 AlCl3 (aq) + 3 Cu (s)

The activity series of metals (Table 11.2) is a list of metals in order of decreasing activity. It is used to predict single replacement reactions involving metallic elements and metallic ions. If the element is higher on the list than the ion, the element will replace the ion.

Double Replacement Reactions

Double replacement reactions (or double displacement reactions) involve the exchange of cations between reactants, i.e. the cations trade places. The reactants are usually aqueous solutions of ionic substances. They follow the general format of

AX + BY → AY + BX

For example: Na2S (aq) + Cd(NO3)2 → 2 NaNO3 (aq) + CdS (s)

The products of these reactions are precipitates (insoluble solids), gases, and liquids. In the example above, either of the products can be precipitates, gases, or liquids.

Neutralization Reactions

Neutralization reactions involve the reaction of an acid with a base to form a salt and water. In these reactions, the hydrogen ion H+ of the acid combines with a hydroxide ion (OH)- to form water. The cation of the base combines with the anion of the acid for form a salt. The general format would be

Acid + Base ( Salt + Water

HX + BOH → BX + H2O

For example: HCl (aq) + KOH (aq) ( KCl (aq) + H2O (l)

Note that the “salt” in the above reaction is KCl. A salt is a general category of ionic compounds composed of a cation from a baser and an anion from an acid. NaCl is an example of a salt in the chemical sense. But in chemistry, a salt does not necessarily mean NaCl (table salt). There are many possible compounds that are “salts.”

Types of Chemical Reactions: Part I

Balance following equations and classify the following the reactions.

Reaction Type

1) ____ NaBr + ____ Ca(OH)2 ( ___ CaBr2 + ____ NaOH ______________________________

2) ____ NH3+ ____ H2SO4 ( ____ (NH4)2SO4 ______________________________

3) ____ C5H9O + ____ O2 ( ____ CO2 + ____ H2O ______________________________

4) ____ Pb + ____ H3PO4 ( ____ H2 + ____ Pb3(PO4)2 ______________________________

5) ____ Li3N + ____ NH4NO3 ( ___ LiNO3 + ___ (NH4)3N ______________________________

6) ____ HBr + ___ Al(OH)3 ( ___ H2O + ___ AlBr3 ______________________________

7) ____ K2O (s) + ____ H2O (l) ( ____ KOH (aq) ______________________________

8) ____ C19H40 (s) + ____ O2 (g)( ____ CO2(g) + ____ H2O (l) ______________________________

9) ____ Rb (s) + ____ H2O (l)( ____ H2 (g) + ____ RbOH (aq) ______________________________

10) ____ Hf (s) + ____ N2 (g)( ____ Hf3N4 (s) ______________________________

11) ____ Mg (s) + ____ H2SO4 (aq) ( ____ MgSO4 (aq) + ____ H2 (g) ______________________________

12) ____ C2H6 (g) + ____ O2 (g) ( ____ CO2 (g) + ____ H2O (l) ______________________________

13) ____ Pb(NO3) 2 (aq) + ____ NaI (aq) ( ____ PbI2 (s) + ____ NaNO3 (aq)______________________________

14) ____ Fe (s)+ ____ O2 (g)( ____ Fe3O4 (s) ______________________________

15) ____ N2O3 (g) + ____ H2O (l) ( ____ HNO2 (aq) ______________________________

16) ____ HI ( ____ H2 + ____ I2 ___________________

17) ____KClO3 ( ____ KCl + ____ O2 ___________________

Typs of Chemical Reactions: Part II

Single Replacement Reactions and the Activity Series[1]

Use the Activity Series to predict and balance the following single replacement reactions. Indicate the appropriate phase of reactants and products where possible. If a reaction does not occur, write “NR” for no reaction.

1. A piece of copper is dropped into a container of water.

2. Liquid bromine is added to a container of sodium iodide crystals.

3. An aluminum strip is immersed in a solution of silver nitrate.

4. Zinc pellets are added to a sulfuric acid solution.

5. Fluorine gas is bubbled into a solution of aluminum chloride.

6. Magnesium slivers are added to a solution of lead (II) acetate.

7. Iodine crystals are added to a solution of sodium chloride.

8. Calcium metal is added to a solution of nitrous acid.

9. A pea-sized piece of lithium is added to water.

10. A solution of iron (III) chloride is poured over a piece of platinum wire.

Types of Chemical Reactions: Part III

A Challenging Assignment

Write balanced chemical equations for the following. Some equations may be word equations, incorrectly written or missing a reactant or product(s). If so, correct each equation and then balance it.

1) Ag2O (s) + heat →

2) ammonium nitrate → dinitrogen monoxide + water

3) Cl2 + NaI → NaCl2I

4) NH3 →N + H3

5) Na + O2 →NaO2

6) Hydrogen + bromine →

7) Write the equation for the combustion of decane (C10H22).

8) Aluminum metal is obtained from aluminum oxide with the addition of a large amount of electrical energy. Write the balanced chemical equation and classify the reaction.

9) Hydrochloric acid reacts with calcium hydroxide to yield calcium chloride and water.

10) Magnesium metal reacts with hydrochloric acid to yield magnesium chloride and hydrogen gas.

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[1] Hague, George and Jane Smith. The Ultimate Chemical Equations Handbook. Batavia: Flinn Scientific, 2006.46

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