SNC 2P - Chemistry - Single Replacement Reactions

Single replacement reactions involve one element replacing another element in a compound.

The general formula is:   

X   +    YZ   →   Y   +   XZ    

or   

element + compound → new element + new compound

This is analogous to a person breaking in on a dancing couple.

 

Some lone elements are “special” and will be found as diatomics or polyatomics: H₂, O₂, N₂, F₂, Cl₂, Br₂, I₂, P₄, S.

All other elements are monatomics:  Fe, Ca, Li, etc.

Remember:  Elements combined in compounds use their valances to determined the ratios in a compound.

 

Practice Questions:

For each of the following (a) complete the word equation, (b) create a balanced equation.

(a) potassium + lithium bromide  →

(b)  sodium + copper (II) chloride   →

(c)  magnesium + aluminum nitride   →

 

Answers:

(a) potassium + lithium bromide → potassium bromide + lithium

              K      +         LiBr            →              KBr            +     Li

 

(b) sodium + copper (II) chloride → copper + sodium chloride

         Na     +          CuCl₂            →   Cu    +          NaCl

 

(c) magnesium + aluminum nitride → aluminum + magnesium nitride

           3Mg       +          2AlN           →     2Al       +          Mg₃N₂

 

Homework:

Answers:

SNC 2P - Decomposition & Combustion Reactions

Decomposition Reactions

Decomposition reactions involve the splitting apart of a compound into simpler element.

The general formula is:   

XY     →     X     +     Y  

or    

compound   →   element   +   element

This is analogous to the man and a woman breaking up.

 

Some lone elements are “special” and will be found as diatomics or polyatomics: H₂, O₂, N₂, F₂, Cl₂, Br₂, I₂, P₄, S₈.

All other elements are monatomics:  Fe, Ca, Li, etc.

Remember:  Elements combined in compounds use their valences to determined the ratios in a compound.

 

Practice Questions:

For each of the following (a) complete the word equation, (b) create a balanced equation.

(a) hydrogen oxide  →

(b)  nitrogen triiodide   →

(c)  calcium sulfide   →

 

Answers:

(a) hydrogen oxide   →   hydrogen   +   oxygen

             2H₂O           →       2H₂        +      O₂    

(b) nitrogen triiodide   →   nitrogen   +   iodine

                2NI₃            →       N₂        +     3I₂

(c) calcium sulfide     →     calcium     +     sulfur

              8CaS           →        8Ca       +        S₈

 

Combustion Reactions

Combustion reactions involve the burning of a hydrocarbon in oxygen to produce carbon dioxide and water.

The general formula is:   

hydrocarbon  +  oxygen  →  carbon dioxide  +  water    

An example is:

CH₄    +    2O₂    →    CO₂    +    2H₂O

 

Homework:

Do the "Decomposition Reactions" at the bottom of the page.

Answers:

 

SNC 2P - Chemistry - Synthesis Reactions

Synthesis reactions involve the combination of simple elements to create a complex compound.

The general formula is:   

X     +     Y     →     XY   

 or    

element   +   element   →   compound

This is analogous to a man and a woman forming a relationship.

 

Some lone elements are “special” and will be found as diatomics or polyatomics: H₂, O₂, N₂, F₂, Cl₂, Br₂, I₂, P₄, S₈.

All other elements are monatomics:  Fe, Ca, Li, etc.

Remember:  Elements combined in compounds use their valences to determine the ratios in a compound.

 

Practice Questions:

For each of the following (a) complete the word equation, (b) create a balanced equation.

(a) hydrogen   +   oxygen  →

(b)  sodium    +   chlorine   →

(c)  lithium   +   fluorine   →

Answers:

(a) hydrogen   +   oxygen  →   hydrogen oxide

           2H₂      +       O₂     →     2H₂O

 

(b) sodium    +   chlorine   →   sodium chloride

        2Na      +       Cl₂       →     2NaCl

 

(c) lithium   +   fluorine   →   lithium fluoride

         2Li      +       F₂      →     2LiF

 

Homework:

Do the "Synthesis Reactions" at the top of the page.

Answers:

 

SNC 2P - Chemistry - Types of Chemical Reactions

Types of Chemical Reactions

Synthesis Reaction

A synthesis reaction is a chemical reaction in which two (or more) substances react to form one product.  The following general equation represents a synthesis reaction:

2H₂  +  O₂  →  2H₂O

  

Decomposition Reaction

A decomposition reaction is a chemical reaction in which one substance is broken down into two (or more) simpler substances.  The following general equation represents a    decomposition reaction:

2HgO  →  2Hg  +  O₂

 

Single Replacement Reaction

A single replacement reaction is a chemical reaction in which one element replaces another element in a compound  The following general equation represents a single replacement reaction:

Na  +  AgCl  →  NaCl  +  Ag

 

Double Replacement Reaction

A double replacement reaction is a chemical reaction which involves the reaction of two compounds to form two new compounds.  The following general equation represents a double replacement reaction:

2KF  +  SrCl₂  →  SrF₂  +  2KCl

 

Exothermic Reaction

An exothermic reaction is a chemical reaction that releases energy (heat) to the surroundings.

 

Endothermic Reaction

An endothermic reaction is a chemical reaction that absorbs energy (heat) from the surroundings.  

 

 

Signs that a Chemical Reaction has Occurred

1. Formation of a precipitate (you will see anything from a cloudy solution to full-on chunks)
   
   
   
   
2. Permanent colour change (you will see a change of colour that lasts for at least 20 seconds)
   
   
   
   
3. Formation of a gas (you will see anything from a bubble every several seconds to full-on crazy)
   
   
   
   
4. Release or absorption of energy (you will feel the reaction vessel get colder or hotter)
   
   
   
   

Question of the Day #15:  

What type of reaction is represented by each of the following equations?  Also, balance each equation.

(a) Al + Fe₂O₃ →  Al₂O₃ + Fe

(b) HgO → Hg + O₂

(c) Fe + H₂SO₄ → FeSO₄ + H₂

(d) KF + NaCl → KCl + NaF

(e) Fe + Cl₂ → FeCl₃

Homework:

Answers: