How would you identify the missing coefficient in the balanced equation and classify the type of reaction?

#Mg(OH)_2 + H_2SO_4 -> MgSO_4 + H_2O#

2 Answers
May 23, 2017

Answer:

#"Mg(OH)"_2 "(s)"+ "H"_2"SO"_4 "(aq)" -> "MgSO"_4 "(aq)"+ color(blue)(2)"H"_2"O(l)"#

Explanation:

In order for the reaction to be balanced, the number of atoms of each element must be equal on both sides of the reaction arrow. On the left side, we have

#"Mg": 1#
#"O": 2 + 4 = 6#
#"H": 2 + 2 = 4#
#"S": 1#

And on the right side,

#"Mg": 1#
#"O": 4 + 1 = 5#
#"H": 2#
#"S": 1#

You'll notice that the products side is short two hydrogens and one oxygen. Coincidentally, #"H"_2"O"# just so happens to have that exact element ratio. We need one more #"H"_2"O"# molecule on the products side to balance this equation, so its coefficient becomes

#1# (understood, not shown) + #color(red)(1) = color(blue)(2)#

The balanced chemical equation is thus

#"Mg(OH)"_2 "(s)"+ "H"_2"SO"_4 "(aq)" -> "MgSO"_4 "(aq)"+ color(blue)(2)"H"_2"O(l)"#

This type of reaction is a special kind of double-replacement reaction (or metathesis reaction) called a neutralization reaction, in which an acid and a base react in aqueous solution to form a salt and (usually liquid) water.

May 23, 2017

Answer:

#Mg(OH)_2# + #H_2SO_4# => #MgSO_4# + #2H_2O#

Metathesis Reaction or, Double Replacement Reaction or, Acid Base Reaction or, Ion Exchange Reaction.

Explanation:

There are two primary classifications of reactions
1. Oxidation-Reduction Reactions
2. Metathesis Reactions

Oxidation-Reduction Reactions are characterized by a change in oxidation states of the elements in the reaction.

Metathesis Reactions are Ion Exchange Reactions of the form
AX + BY => AY + BX where A, B, X & Y are Ions in aqueous solution. For a Metathesis Ion Exchange Reaction to occur, a product is formed that leaves the reaction system as a solid precipitate, soluble weak acid or weak base or a gas decomposition product. The Metathesis Reactions reaction is characterized by NO CHANGE in oxidation states of elements in the reaction process.