04 Writing Word Equations for Chemical Reactions

01 Interpreting Word & Chemical Equations:

In the reaction of the combustion of carbon to form carbon dioxide:

Carbon + oxygen gas -> Carbon dioxide gas [Word Equation]

Carbon and oxygen gas are reactants. Carbon dioxide gas is the product.

C (s)     +   O2  (g) -> CO2  (g)  [Chemical Equation]

C and O are chemical symbols of carbon and oxygen element.
Oxygen is a diatomic molecule so it appears as O2 . 
(s) and (g) are called state symbols ; they represent the state of the substance during the reaction.

You will learn more about writing chemical equations later. Now, you just focus on writing word equations. 

02) How do we write the name of the compound formed? 

Referring to the notes of naming compounds : Click here for recap on naming compounds.

03) Word Equation of Combination 

a) Sodium + chlorine gas -> sodium chloride
b) iron + sulfur -> iron sulfide
c) magnesium + oxygen -> magnesium oxide

04) Word Equation of Combustion/Rusting 

a) Combustion of Fuels:
i) Methane gas + oxygen gas -> carbon dioxide gas + water

b) Rusting of Iron 
Iron + oxygen -> Iron (III) oxide

Note: iron (III) refers to the charge the iron has when forming a compound with oxygen. It means it has a charge of 3+. You will study the charges of each element when forming compound later on. You will only need to write this (I), (II)  or (III) etc for certain elements. 

05) Word Equation of Decomposition 

a) Copper (II) Carbonate -> Copper (II) oxide + carbon dioxide
b) Zinc nitrate -> zinc oxide + nitrogen dioxide + oxygen
c) Water -> hydrogen + oxygen (Electrolysis)

06) Word Equation of Precipitation 

a) lead (II) nitrate + potassium iodide -> potassium nitrate + lead (II) iodide (yellow precipitate) 
b) copper (II) nitrate + sodium hydroxide --> copper (II) hydroxide (blue precipitate) + sodium nitrate

07 Complete the Exercise in this link provided as a group.