11 Chemistry – Unit 1- Types of reactions

Read p. 119-140 and answer the following questions which will serve as notes.

Synthesis Reactions

Definition of synthesis reactions:

Two or more elements or compounds combine to form a new substance

ie. A + B  C

A. Simple synthesis reactions

Definition of simple synthesis reactions:

One element reacts with one or more other elements to form a compound

Describe the two types of simple synthesis reactions and give two balancedexamples of each.

Type 1:metal element or nonmetal element + oxygen  oxide

Eg. 1: 3 Fe(s) + O2(g) Fe3O2(s)

Eg. 2:2H2(g) + O2(g) 2H2O (g)

Type 2: metal + non-metal  binary compound

Eg. 1:2 K (s) + Cl2(g) 2KCl (s)

Eg. 2 (think of one):

B. Synthesis reactions involving compounds as reactants

Type 1: _non-metallic oxide__ reacting with water.(non-metallic oxide + H2O  acid)

What type of product is formed in these type of reactions. ___acid____(hydrogen cations and polyatomic anions containing O and a non-metal).______

Give two examples (balanced!):

Eg 1: SO3(g)+ H2O(l) H2SO4 (aq)

Eg 2: CO2 + H2O ___ H2CO3 (aq)______

Type 2: __metallic oxide___ reacting with water.

What type of product is formed in these type of reactions. ___metal hydroxide__(type of base)__

Give two examples (balanced!):

Eg 1: CaO (s)+ H2O(l) Ca(OH)2 (aq)

Eg 2: Na2O + H2O __2 NaOH______

Do synthesis reactions always produce only one type of product? No (you can only guess at what will happen)

Give two examples: Eg 1: C(s)+ O2(g) CO2 (g)

Eg 2: 2 C(s)+ O2(g) 2 CO (g)

DecompositionReactions

Define a decomposition reaction: a compound breaks down into elements or other compounds

What are two types of decomposition reactions and give an example of each.

Type 1: compound  component elements

Eg 2H2O(l) 2H2 (g) + O2 (g)(happens when electricity is passed through water)

Type 2: compound other compounds

Eg. NH4NO3(s) N2O (g) + 2H2O (g)

CombustionReactions

Define a complete combustion reaction: reaction of a compound or element with oxygen to form the most common oxide of that element or compound.

Ex. A carbon-containing compound undergoes combustion to form:CO2 (g)

A sulfur containing compound undergoes combustion to form: SO2 (g)

Combustion reactions are usually also accompanied by the production of:heat and light

What are the main products for a compound containing carbon, hydrogen, and oxygen: CO2 and H2O

Eg. C2H5OH(l)+ 3O2 (g) 2 CO2 (g) + 3H2O (g)

Complete combustion reactions are often also _synthesis_ reactions. Metals undergo combustion to form their stable oxide.

Eg. 2Mg(s) + O2(g) 2MgO (s)

Define an incomplete combustion reaction: occurs in the absence of sufficient oxygen leading to COand H2O

Why is it an important reaction to be aware of?CO is deadly, you should always make sure there is enough oxygen in your indoor environment for gas furnaces, stoves and/or fireplaces

Single Displacement Reactions

Define a single displacement reaction: one element in a compound is replaced by another element.

Describe the two types of single displacement reactions and give and example of each.

Type 1: metal replaces metal cation (A + BC  AC + B)

Eg. Zn (s) + FeNO3 (aq)  Zn(NO3)2(aq) + Fe (s)

Type 2: non-metal (usually a halogen) replaces an anion

Eg. Cl2 (g) + CaBr2 (aq)  CaCl2(aq) + Br2 (s)

A. Single displacement and the metal activity series

Describe the three types of single displacement reactions that involve metals and give an example for each.

Type 1: one metal replaces ANOTHER METAL in an ionic compound.

Eg. Cu (s) + 2 AgNO3 (aq)  Cu(NO3)2(aq) + 2 Ag (s)

Type 2: a metal replaces HYDROGEN in an ionic compound.

Eg. Mg (s) + 2 HCl (aq)  MgCl2(aq) + H2 (g)

Type 3: a metal replaces HYDROGEN in WATER.

Eg. 2Na(s) + 2 H2O (l)  2NaOH(aq) + H2 (g)

*Treat hydrogen as a metal

*Treat acids as ionic (H+ Cl-) (H+H+ SO42-)

*Treat water as ionic (H+ OH-)

The metal Activity Series

Copy table 4.2 on p. 130 below

Metal / Displace hydrogen from acids / Displaces hydrogen from cold water
Li / / / Most reactive
K /
Ba
Ca
Na
Mg
Al
Zn
Cr
Fe
Cd
Co
Ni
Sn
Pb
H
Cu
Hg
Ag
Pt
Au / Least reactive

Describe how to use the series:

It ranks the reactivity of metals (and hydrogen) in acids and water.

A reactive metal will displace any metal in a compound that is below it on the series.

Ex. Fe (s) + CuSO4 (aq)  FeSO4(aq) + Cu (s)

Ag (s) + CaCl2 (aq)  No Rxn(because Ca is more reactive than Ag)

B. Single displacement and Halogens

Give and example of a S.D.R. involving two halogens

Eg.:Cl2 (g) + 2KBr (aq)  2KCl (aq) + Br2 (g)

What is the activity series for halogens and describe how to use it? Give two examples.

Activity series for Halogens is in the same order as the Periodic Table

F

Cl

Br

I

So F > Cl > Br > I

Eg 1:F2 (g) + 2NaCl (aq)  2NaF (aq) + Cl2 (g)

Eg 2:I2 (g) + CaBr2 (aq)  No Rxn

Hwk:

Synthesis: p. 122 # 10, 11 a, b, 12, 13;

Decomposition: p. 123 # 15, 16;

Synth and Decomp: p. 125 # 1 a, b, c, 2 a, b, c

Combustion: p. 124 # 17-20

Single Displacement: p. 127 # 21 p. 131 # 22, 23, 24

11 Chemistry – Unit 2- Types of reactions

Double Displacement Reactions

Read p. 132-135

Define a double displacement reaction (include the general equation):

Involves the exchange of cations between two ionic compounds, usually in solution.

What are the three indications of a D.D. reaction?

1) precipitate forms (solid forms from two liquids being mixed)

2)gas is produced

3)water is formed

1) Define a precipitate: a solid compound that separates from a solution as the result of a chemical reaction

Write out the reaction of barium chloride solution and potassium sulphate solution. Write out the products in their proper states. Look up each of the reactants and products on the solubility chart handed out (back side of reactivity series).

BaCl2 (aq) + K2SO4 (aq)  2KCl(aq) BaSO4 (s)

Why is the barium sulphate a solid? _____insoluble in water______

Why is potassium chloride aqueous?_____ soluble in water______

Why are barium chloride and potassium sulphate aqueous? ______soluble in water______

N.B. a reaction occurs only if at least one of the products is insoluble.

Do # 25 on p. 134 in your notes.

What does N.R. mean? ____no reaction______

2) Give an example of a D.D. reaction that produces a gas.

Na2CO3 (aq) + 2HCl(aq)  2 NaCl(aq) + { H2CO3(aq) } – but this compound is unstable in water and splits into water

and carbon dioxide gas

Na2CO3 (aq) + 2HCl(aq)  2 NaCl(aq) + H2O(l) + 2CO2(g)

3) Define a neutralization reaction (what are the reactants?):

Acid + Base  water + ionic compound (binary salt)* to identify Acid: look for H…(aq)

* to identify Base: look for …OH(aq

H2SO4 (aq) + 2NaOH(aq) 2H2O(l) + Na2SO4 (aq)

Hwk: p. 135 # 27, 28 a,b;p. 140 #1,2, 4, 6