Chemistry - Chemical Reactions, Predicting Products, and Balancing Equations

What are chemical reactions?

The process where substances change into different substances, involved breaking and forming chemical bonds, results in new products with different properties

What is the left side of a chemical equation called?

Reactants

What is the right side of a chemical equation called?

Products

What are reactants?

Starting materials in chemical reactions. Substances that undergo change during the reaction

What are products?

Substances form as a result of a chemical reaction. Outcome/end of the reaction

What are the five types of reactions?

Synthesis reactions, decomposition reactions, single displacement reactions, double displacement reactions, and combustion reactions

What are synthesis reactions?

When 2 or more reactions combine to form a single product

What is the general form of synthesis reactions?

A + B -> AB

What are decomposition reactions?

When a single compound breaks down into 2 or more simpler substances

What is the general form of decomposition reactions?

AB -> A + B

What are single displacement reactions?

When one element replaces another in a compound

What is the general form of single displacement reactions?

A + BC -> AC + B

What are double displacement reactions?

When 2 compounds exchange partners

What is the general form of double displacement reactions?

AB + CD -> AD + CB

What are combustion reactions?

When a substance reacts rapidly with oxygen and releases energy. Often involves hydrocarbons and must involve oxygen as one reactant

What is the general form of combustion reactions?

Fuel + O₂ -? HO₂

2H₂ + O -> 2H₂O this is an example of?

Synthesis reaction

2H₂O -> 2H₂ + O₂ this is an example of?

Decomposition reaction

Zn + 2HCl -> ZnCl₂ + H₂ this is an example of?

Single displacement reaction

NaCl + AgNo₃ -> NaNo₃ + AgCl this is an example of?

Double displacement reaction

H + O₂ -> HO₂ this is an example of?

Combustion reaction

How do you predict the product of a synthesis reaction?

Combine the reactant and determine the correct chemical formula

How do you predict the product of a decomposition reaction?

Think about what simpler substances could make up the original formula

How do you predict the product of a single displacement reaction?

Replace the element with the corresponding element in the compound (remember to correct charges and balance at the end)

How do you predict the product of a double displacement reaction?

Swap the ions between the 2 compounds

How do you predict the product of a combustion reaction

It is ALWAYS CO₂ + H₂O (sometimes + Energy)

What is the product of 2Na + Cl₂ and what reaction is it?

2NaCl. Synthesis

What is the product of Mg + O₂ and what reaction is it?

2MgO Synthesis

What is the product of 2H₂O and what reaction is it?

2H₂ + O₂ Decomposition

What is the product of NaF and what reaction is it?

Na + F₂ Decomposition

What is the product of CuSO₄ + Zn and what reaction is it?

Cu + ZnSO₄ Single displacement

What is the product of LiI + F₂ and what reaction is it?

2I₂ + LiF₂ Single Displacement

What is the product of Pb(NO₃)₂ + KI and what reaction is it?

PbI₂ + 2KNO₃ Double displacement

What is the product of BaCl₂ + Na₂SO₄ and what reaction is it?

BaSO₄ + NaCl Double displacement

What is the product of CH₄ + 2O₂ and what reaction is it?

CO₂ + 2H₂O + Energy Combustion

Why do we balance equations?

It ensures we follow Law of Conservation of Mass (matter cannot be created or destroyed, but it can be rearranged). Shows the correct ratios of reactants and products. Helps us to predict quantities needed for reactions

Law of Conservation of Mass states that?

The total mass of reactants equals the total mass of products (the number and type of atoms going into a rxn must be the same as the number and type of atoms coming out)

What does a subscript show?

How many atoms of an element are in a molecule (H₂O - there are 2 atoms of hydrogen, 1 atom of oxygen)

What does a coefficient show?

How many molecules there are of a particular chemical (3H₂O - there are three water molecules)

What are the steps to balance an equation?

1) Write the unbalanced equation

2) Count the atoms on both sides

3) Start with the most complex molecule

4) Balance metals, then non-metals

5) Add coefficients to balance the atoms

6) Balance hydrogen and oxygen last

7) Verify final equation

(never change subscripts, only coefficients)

Balance Mg + O₂ -> MgO

2Mg + O₂ -> 2MgO

Balance CH₄ + O₂ -> CO₂ + H₂O

CH₄ + 2O₂ -> CO₂ + 2H₂O

Balance CuO + NH₃ -> Cu + N₂ + H₂O

3CuO + 2NH₃ -> 3Cu + N₂ + 3H₂O

Do you always reduce coefficients to the lowest-common ratio when possible?

Yes

Do all parts of the equation need to have a coefficient in order to reduce to the lowest-common ratio

Yes

Reduce 2H₂ + 4N + 2H₂N

H₂ + 2N + H₂N

Reduce 2H₂ + N + 2H₂N

Cannot be reduced

What should you do when balancing equations if there are parenthesis

Treat everything inside as a single unit. When there is a subscript outside of the parenthesis, then multiply it with everything inside

Balance Ca + H₂O -> Ca(OH)₂ + H₂

Ca + 2H₂O -> Ca(OH)₂ + H₂

Balance Al(NO₃)₃ + Ca(OH)₂ -> Al(OH)₃ + Ca(NO₃)₂

2Al(NO₃)₃ + 3Ca(OH)₂ -> 2Al(OH)₃ + 3Ca(NO₃)₂