1.7 Redox Flashcards
What is oxidation
The loss of electrons
What is reduction
The gain of electrons
What is a redox reaction
Transfer of e-
e- lost must equal e- gained
What is a half equation
Separate equations showing the oxidation and reduction process
Must be balanced in terms of atoms and charge
What is an oxidation state
OS of an element is the number of electrons involved when at atom forms a bond
OS state refers to one atom of the element in a compound or ion
OS has a number and a sign
What are the rules for assigning OS
-An uncombined element has an OS of zero
-Some elements have the same OS in all their compounds
-For a compound, the OS of each atom in the compounds formula counts separatley and the numerical sum is zero
-For an element exsisting as an ion , the OS is the charge on that ion
-For compound ions the sum of the OS of the atoms is the charge on the ion
What is the exceptions of the OS of H
Normally +1
In metal hydrides it is -1
What is the exception of the OS of O
Normally -2
In peroxides and when combined with F it is -1
What is the exception for the OS of Cl
Normally -1
When combined with O it varies
What do roman numeral indicate
The OS
To differentiate between oxo-acids
Naming salts and oxo-anions
How do OS link with redox reactions
Oxidation is an increase in OS
Reduction is a decrease in OS
What is an oxidising agent
A specis that accepts electrons
What is a reducing agent
A species that donates electrons
How do you balance more complex half equations
-Balance atoms undergoing redox
-Balance any oxygen atoms by adding water
-Balance H atoms by adding H+ ions
Balance charges by adding electrons
How do you combine half -equations
One equation must show oxidation and the other reduction
The number of e- being transferred but be the same
2 half equations can be added and any species that appears on both sides of equation are canclled
