Types of reactions
This type of reaction has the general form A + B → AB.
Synthesis reaction
What is the purpose of balancing a chemical equation?
Obey the law of conservation of mass
A color change is evidence of what type of process?
Chemical reaction
Compare exothermic and endothermic reactions.
In an exothermic reaction, energy is released from the system to the surroundings, usually as heat (sometimes light or sound). This means the surroundings feel warmer. In an endothermic reaction, energy is absorbed from the surroundings into the system. This makes the surroundings feel colder.
What does the term “aqueous” mean in a chemical equation?
Dissolved in water (in solution)
This reaction breaks one compound into simpler substances (AB → A + B).
Decomposition reaction
Balance this equation: H₂ + O₂ → H₂O
2H₂ + O₂ → 2H₂O
Formation of bubbles indicates the production of what?
Gas
Predict the products and identify the type of reaction:
BaCl₂ + Na₂SO₄ → ?
BaSO₄ + 2NaCl, a double replacement reaction?
When an ionic compound dissolves in water, what happens to it?
Dissociates into ions
In this reaction, one element replaces another in a compound.
Single replacement reaction
In balancing equations, what cannot be changed: coefficients or subscripts?
Subscripts
This is the formation of a solid in a solution.
precipitate
Predict the products and identify the type of reaction:
Al + CuCl₂ → ?
AlCl₃ + Cu, a single replacement reaction?
When NaCl is dissolved in water, it separates into Na⁺ and Cl⁻ ions. Why does this allow the solution to conduct electricity?
Because the free-moving ions carry electrical charge through the solution
This reaction involves the exchange of ions between two compounds.
Double replacement reaction
Balance the equation Fe + O₂ → Fe₂O₃
4Fe + 3O₂ → 2Fe₂O₃
When two clear solutions are mixed and the result becomes cloudy, what is the evidence of a chemical reaction?
Formation of a precipitate (solid)
Predict the products and determine if a reaction occurs:
Pb(NO₃)₂ + KI → ?
PbI₂ + KNO₃, a double replacement reaction
What does it mean when a substance is labeled (aq) in a chemical equation, and how is it different from (l)?
(aq) means dissolved in water as ions or molecules, while (l) means a pure liquid substance
This type of reaction involves oxygen and produces CO₂ and H₂O when hydrocarbons burn.
Combustion reaction
Balance the following equation:
C₂H₆ + O₂ → CO₂ + H₂O
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
In a combustion reaction, hydrogen combines with oxygen. What is one of the products formed?
Water (H₂O)
Predict the products and determine if a reaction occurs:
BaCl₂ + K₂CO₃ → ?
BaCO₃ + 2KCl, a double replacement reaction
What is the solution composed of, and what is their definitions?
Solute: The substance or substances that you want to dissolve
Solvent: The substance that is used to dissolve the solute