Redox Reactions - OCR Chemistry - Unit 1, Module 1

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What is an oxidation number?
A measure of the number of electrons that an atom uses to bond with atoms of another element. Oxidation numbers are derived from a set of rules.
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What is the oxidation number of an uncombined element?
0
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What is the oxidation number of combined oxygen?
-2
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What is the oxidation state of combined hydrogen?
+1
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What is the oxidation number of a simple ion equal to?
The charge on the ion.
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What is the oxidation number of combined fluorine?
-1
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In compounds and molecular ions must equal...
... the overall charge on the ion.
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What are oxyanions?
Oxyanions are negative ions that contain an element along with oxygen.
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What is the oxidation state of nitrogen in: NO3- and N2O5
Oxiation state of nitrogen in NO3 and N2O5 is +5.
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What is the definition of oxidation?
Oxidation is the loss of electrons or an increase in oxidation number.
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What is reduction?
Gain of electrons or a decrease in oxidation number
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What is a redox reaction?
A reaction in which both oxidation and reduction take place.
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In the reaction of magnesium and chlorine, which element is the reducing agent and why? What are the half equations?
Magnesium is the reducing agent because it has reduced the chlorine from oxidation state zero to -1. The half equation for chlorine is Cl2 + 2e- -> 2Cl-
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In redox reactions with a metal and acid what happens?
The metal is oxidised, forming positive metal ions. The hydrogen in the acid is reduced, forming the element hydrogen as a gas.
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Write the equations for the reaction of: Iron + Hydrochloric acid --> Iron (II) chloride + hydrogen gas
Fe --> Fe2+ + 2e- (oxidised- Fe has gone from oxidaion 0 to +2) and H+ + e- --> H2 (reduced, gone from +1 to zero)
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Card 2

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What is the oxidation number of an uncombined element?

Back

0

Card 3

Front

What is the oxidation number of combined oxygen?

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Card 4

Front

What is the oxidation state of combined hydrogen?

Back

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Card 5

Front

What is the oxidation number of a simple ion equal to?

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