Redox-physical chemistry Flashcards
What are oxidation and reduction?
Oxidation = Loss of electrons (OIL: Oxidation Is Loss).
Reduction = Gain of electrons (RIG: Reduction Is Gain).
Oxidising agents accept electrons (cause oxidation).
Reducing agents donate electrons (cause reduction).
What is an oxidation state?
The oxidation state (oxidation number) of an element is a measure of the number of electrons it has lost or gained in a compound or ion.
How do you combine half-equations?
Multiply half-equations so that electrons cancel out.
Add the two half-equations together.
How do you write a half-equation for a redox reaction?
Identify the element being oxidised (loses e⁻) and the element being reduced (gains e⁻).
Balance atoms and charge using electrons (e⁻).
What is the oxidation state of an element in its standard form?
For an element in its uncombined state (e.g., O₂, Cl₂, Fe, Ne), the oxidation state is always 0.
How do you determine the oxidation state of a monatomic ion?
For a single-atom ion, the oxidation state is the same as its charge.
What are the oxidation states of Group 1 and Group 2 metals?
Group 1 metals (e.g., Na, K, Li) = Always +1.
Group 2 metals (e.g., Mg, Ca, Ba) = Always +2.
What is the oxidation state of fluorine in all compounds?
Fluorine is always -1 in compounds because it is the most electronegative element.
What is the usual oxidation state of oxygen?
Oxygen usually has an oxidation state of -2, except:
In peroxides (H₂O₂, Na₂O₂), oxygen is -1.
In compounds with fluorine (e.g., OF₂), oxygen is +2.
What is the oxidation state of hydrogen?
In most compounds, hydrogen is +1 (e.g., H₂O, NH₃).
In metal hydrides (e.g., NaH, CaH₂), hydrogen is -1.
What is the sum of oxidation states in a neutral compound?
The sum of oxidation states in a neutral compound must be 0.
What is the sum of oxidation states in a polyatomic ion?
The sum of oxidation states in a polyatomic ion must equal the charge on the ion.
