Chemical Reactions

Chemical Equations

1

C₈H₁₈ + O₂ --> CO₂ + H₂O

What is on the left of the arrow?

What is on the right of the arrow?

What does the arrow mean?

Reactants - left of the arrow

Products - right of the arrow

"Yields"  - meaning of the arrow

3 Points 

2

C₈H₁₈ (g) + O₂ (g) --> CO₂ (g) + H₂O (l)

What do the letters in the parentheses indicate?

They're abbreviations that indicate the state of matter.

2 points

3

What do these abbreviations mean?

(g), (l), (s), (aq)

(g) - gas

(l) - liquid

(s) - solid

(aq) - aqueous (dissolved in water)

4 points

4

What is the law of conservation of mass?

Matter can't be created or destroyed in a chemical reaction

Mass of the reactants should equal the mass of the products

2 points

5

What are 5 signs that a chemical reaction has occurred. 

Formation of a gas

Formation of a precipitate 

Change in color 

Change in odor 

Change in energy

5 points

Rules for Balancing Chemical Equations

1

How would you conserve mass when balancing equations?

Each side of a chemical reaction must have the same number of atoms

2 points

2

What are coefficients?

Numbers placed in front of the reactants and products so that the number of reactant atoms are the same as the number of product atoms.

1 point

3

What two elements should you try to leave for last when balancing equations and why?

Balance for all elements other than hydrogen and oxygen because they are the most abundant and usually will work themselves out by the end.

3 Points 

4

What are the three ways to write a chemical reaction?

Word Equations 

Sentence Form 

Chemical Equations

3 points

5

What are the 5 steps to balancing equations?

Write the reactants and the products in the chemical equation

Draw a line down from the arrow to split the reactant from the products 

Count the number of atoms for each element (or poly) on each side. 

5 points

Try to balance the atoms by changing the coefficient in front of the most complicated molecule.

When all atoms are balanced check to see if you can reduce 

Balancing Chemical Equations

1

Ca₃(PO₄)₂ + SiO₂ + C → P₄ + CaSiO₃ + CO

2Ca₃(PO₄)₂ + 6SiO₂ + 10C → P₄ + 6CaSiO₃ + 10CO

5 points

2

Na₃PO₄ + MgCl₂ → NaCl + Mg₃(PO₄)₂

2Na₃PO₄ + 3MgCl₂ → 6NaCl + Mg₃(PO₄)₂

3 points 

3

Aluminum reacts with iron(III) oxide to produce aluminum oxide and iron.

2Al + Fe₂O₃ → Al₂O₃ + 2Fe

2 points

4

Sodium phosphate reacts with magnesium chloride to form sodium chloride and magnesium phosphate. 

2Na₃PO₄ + 3MgCl₂ → 6NaCl + Mg₃(PO₄)₂

4 points

5

Balance this equation:

ammonium perbromate and potassium oxide yields potassium perbromate and ammonium oxide

ammonium is (NH₄)

2NH₄(BrO₄) + K₂O --> 2K(BrO₄ )+ (NH₄)₂O

4 points

Types of Chemical Reactions

1

What is a synthesis reaction? Provide an example.

A synthesis reaction is when two or more elements combine to form a compound

Example: 2Na + Cl₂ --> 2NaCl

2 points

2

What is a decomposition reaction? Provide an example.

A single compound breaks down into two or more simpler products

Products can be any combination or elements and/or compounds

Example: 2H₂O --> 2H₂ + O₂

_{2 points}

3

What is a combustion reaction ? Give an example.

Combustion requires a fuel and oxygen and always results in carbon dioxide and water vapor.

Example: 2C₈H₁₈ + 25O₂ --> 16CO₂ + 18H₂O

3 points

4

What is a single replacement reaction? Provide an example.

One element replaces another element in a compound

Example: 2Li + MgCl₂ --> Mg + 2LiCl

2 points

5

What is a double replacement reaction? Provide an example.

Two elements exchange places in a compound. Both reactants are aqueous and a precipitate is formed.

Example: AgNO₃ + NaCl --> AgCl + NaNO₃

_{2 points} 

Application of Chemical Reactions

1

Balance the equation then state what type of chemical reaction is present.

__NaCl + __F₂ --> __NaF + __Cl₂

Single Replacement

2NaCl + F₂ --> 2NaF + Cl₂

_{2 points}

2

Balance the equation then state what type of chemical reaction is present.

__H₂ + __O₂ --> __H₂O

Synthesis

2H₂ + __O₂ --> 2H₂O

2 points

3

Balance the equation then state what type of chemical reaction is present.

__CH₄ + __O₂ --> __CO₂ + __H₂O

Combustion

__CH₄ + 2O₂ --> __CO₂ + 2H₂O

2 points

4

Balance the equation then state what type of chemical reaction is present.

_Al₂S₃ --> _Al + _S₂

Decomposition

2Al₂S₃ --> 4Al + 3S₂

_{2 points}

5

What is the chemical reaction for this equation?

ammonium permanganate and potassium oxide yields potassium permanganate and ammonium oxide

Double Replacement

2NH₄MnO₄ + K₂O → 2KMnO₄ + (NH₄)₂O

3 points