Single displacement reactions: are chemical changes that involve an element and a compound as reactants

One element displaces or replaces another element from a compound

Single displacement reactions have the following general formula

Z + AB ZB + AOR

Y + AB AY + B

Case 1: the metal Z has taken the place of the element A (metal always replaces metal)

Case 2: the non-metal Y has taken the place of element (non-metal always replaces non-metal)

An example: a coil of magnesium ribbon is placed in a solution of silver nitrate

Magnesium + silver nitrate silver + magnesium

nitrateMg + 2AgNO3 2Ag + Mg(NO3)2

Another example: bromine is added to a solution of calcium iodide

◦ Bromine will replace/displace the iodide ion

Bromine + calcium iodide iodine + calcium bromide

Br2 + CaI2 I2 + CaBr2

Double displacement reactions: occur when elements in different compounds displace each other or exchange places

They have the following general formula:

AB + XY AY + XB

A and X are metallic elements while B and Y are non-metallic elements.

Example: lead (II) nitrate and potassium iodide

Lead (II) nitrate + potassium iodide lead (II) iodide + potassium nitrate

Pb(NO3)2 + 2KI PbI2 + 2KNO3

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