Unit 6: Chemical Reactions Flashcards
What are reactants?
The substances that undergo change in a chemical reaction.
What are products?
Substances formed as a result of change.
What is a chemical equation?
A representation of a chemical reaction in which the reactants and the products are expressed as chemical formulas.
What does the Law of Conservation of mass state?
The mass of a closed system of substances will remain constant. Matter cannot be created or destroyed.
Who established the Law of Conservation of Mass?
Antoine Lavoisier in 1789.
What is a mole?
An amount of substance that contains Avogadro’s number of particles of that substance.
What is Avogadro’s number?
6.02x10^23
What is molar mass?
The mass of one mole of a substance.
What is a synthesis reaction?
Two or more reactants combine to form one product.
A+B->AB
What is a decomposition reaction?
One reactant breaks down into two or more simpler substances.
AB -> A + B
What is a single displacement reaction?
One single element replaces an element in a compound.
AB + X -> XB + A
What is a double displacement reaction?
The ions in two ionic compounds switch places to form two new ionic compounds.
AB + XY -> AY + XB
What is combustion?
Something is burning; reacting rapidly with oxygen. Heat and light are produced, each reaction has oxygen as a reactant and carbon dioxide and water as two products.
What is a redox reaction?
In an oxidation-reduction reaction, electrons are transferred from one reactant to another.
What is oxidation?
An element losing its electrons during a chemical reaction.
What is reduction?
An element gaining electrons during a chemical reaction.
What is chemical energy?
The energy stored in the chemical bonds of a substance. Breaking bonds requires energy, and forming bonds releases energy.
What is an exothermic reaction?
A chemical reaction that releases energy to its surroundings.
Reactants -> products + energy
Energy released > energy required
What are examples of exothermic reactions?
Combustion
Respiration
What is an endothermic reaction?
A chemical reaction that absorbs energy from its surroundings.
Reactants + Energy = Products
Energy required > energy released
What is an example of an endothermic reaction?
Photosynthesis.
What is reaction rate?
The rate at which reactants change into products over time. Measured by how quickly the reactants decrease or how quickly the products increase.
What factors affect reaction rate?
Temperature Surface area Concentration Stirring Pressure Catalysts
What is a catalyst?
A substance that affects the reaction rate without being used up in the reaction.
What is equilibrium?
The state in which the forward and reverse paths of a change take place at the same rate so that the concentration of the reactants and products doesn’t change with time.
What are physical and chemical equilibrium?
Physical is opposing physical changes happening at the same rate, while chemical is opposing chemical changes happening at the same rate.
What are forward and reverse reactions?
Forward reaction is reactants changing into products and reverse reaction is products changing back into reactants.
What is Le Chatelier’s principle?
If a stress is placed on a system at equilibrium, the system will proceed in a direction that minimizes the stress.
