Chemistry: Lesson 5 Chemical Reactions

Front 1

Describe the basic concept of a chemical reaction

Back 1

In a chemical reaction, chemical bonds between atoms in reactants (starting materials) are broken and new bonds are formed in different combinations to form new compounds (the products).

Front 2

Identify and briefly describe a Decomposition Reaction

Back 2

Breaks larger compounds into smaller ones. One substance becomes two.
Catabolism. Breakdown of nutrients to provide energy.
AB > A + B
2CuO > 2Cu + O2
2H2O > 2H2 + O2

Front 3

Identify and briefly describe a Combination Reaction

Back 3

Makes larger compounds from smaller ones. Two substances form one substance.
Anabolism. Synthesis of structural components of cells and tissues
A + B > [AB]
N2 + 3H2 > 2[NH3]
Ca + S > [CaS]

Front 4

Identify and briefly describe a Single Replacement Reaction

Back 4

An atom or molecule replaces an atom or group of atoms from a compound. Always two reactants and two products. An element and a compound are reactants and an element and a compound are products.
A + BC > B + AC
Fe + CuSO4 > Cu + FeSO4
F2 + 2NaCl > Cl2 + 2NaF

Front 5

Identify and briefly describe a Double Replacement Reaction

Back 5

Two substances exchange parts with another and form two different substances. Partner switching.
AB + CD > AC + BD
AgNO3 + NaCl > AgCl + NaNO3 (Silver switches with Sodium)

Front 6

Identify and briefly describe a Combustion Reaction

Back 6

Reaction between a substance and oxygen that proceeds with the production of light and heat. Breakdown of a hydrocarbon to carbon dioxide in water.
2C2H2 + 5O2 > 4CO2 + 2H2O

Front 7

Explain the concept of redox reactions

Back 7

A reaction in which there is a transfer of electrons from one reactant to another reactant; oxidation and reduction.

Front 8

Define the term Oxidation

Back 8

The loss of electrons; the gain of oxygen atoms and/or the loss of hydrogen atoms.

Front 9

Define the term Reduction

Back 9

The gain of electrons; the loss of oxygen atoms and/or the gain of hydrogen atoms.

Front 10

Define the term Oxidizing agent

Back 10

A reactant that causes oxidation of another reactant by accepting electrons from it.

Front 11

Define the term Reducing agent

Back 11

A reactant that causes reduction of another reactant by providing electrons

Front 12

Define the term Exothermic reaction

Back 12

Reactions which give off heat are exothermic.

Front 13

Define the term Endothermic reaction

Back 13

Reactions taking in heat are endothermic.

Front 14

Define the term Exergonic reaction

Back 14

An exergonic reaction is one which generates energy = Exothermic Reaction

Front 15

Define the term Endergonic reaction

Back 15

An endergonic reaction is one which requires energy = Endothermic Reaction

Front 16

Define the term Balance chemical equations

Back 16

In a balanced chemical equation there must be the same number of atoms of each element on both sides and the same mass on each side.

Front 17

Identify the substance that is oxidized, the substance that is reduced, the oxidizing agent and the reducing agent.

Al(s) + Fe3+(aq) > Al3+(aq) + Fe(s)

Back 17

Al (s) loses three electrons and becomes Al3+;
Aluminium is oxidised.
Fe3+ gains three electrons and becomes Fe.
Iron is reduced.
Al is the reducing agent. Fe is the oxidising agent.

Front 18

Identify the substance that is oxidized, the substance that is reduced, the oxidizing agent and the reducing agent.

CH3OH(g) + O2(g) > HCOOH(g) + H2O(g)

Back 18

In converting CH3OH to HCOOH, CH3OH both gains oxygens and loses hydrogens; it is oxidised.
In converting O2 to H2O, O2 gains hydrogens; it is reduced.
CH3OH is the reducing agent. O2 is the oxidising agent.

Front 19

Identify the substance that is oxidized, the substance that is reduced, the oxidizing agent and the reducing agent.

Ni2+(aq) + Cr(s) > Ni(s) + Cr2+(aq)

Back 19

Ni gains two electrons and becomes Ni.
Nickel is reduced.
Cr loses two electrons and becomes Cr2+.
Chromium is oxidised.
Nickel is the oxidising agent. Chromium is the reducing agent.

Front 20

Identify the substance that is oxidized, the substance that is reduced, the oxidizing agent and the reducing agent.

CH2O(g) + H2(g) > CH3OH(g)

Back 20

CH2O gains hydrogen so is reduced.
H2 gains oxygens in being converted to CH3OH and so is oxidised.
CH2O is the oxidising agent. H2 is the reducing agent.