Chapter 4: Chemical Reactions Flashcards
What is the ionic theory of solutions?
Scientists realized you could make water electrically conductive if you add electrolytes to it.
Certain substances produce freely moving ions when they dissolve in water, and these ions conduct an electric current in an aqueous solution.
What is an example of the ionic theory of solutions?
NaCl is placed in water, the positively charged Na ions disperse from the negatively charged Cl ions. The result is that when a battery or electric charge is put in the water, the negatively charged ions go to the negative side and positive go to positive creating an electric wave.
What are the two classes of substances that dissolve in water?
Electrolytes: Substance that dissolves in water to give an electrically conducting solution. (Ionic solids that dissolve in water)
Non-Electrolytes: A substance that dissolves in water to give a nonconducting or very poorly conducting solution (table sugar)
What is the difference between strong and weak electrolytes?
Strong electrolytes: Exist in solution almost entirely as ions.
Weak electrolytes: Dissolve in water to give a relatively small percetage of ions.
What is a molecular equation?
A chemical equation in which the reactants and products are written as if they were molecular substances, even though they may actually exist in solution as ions.
What is the purpose of the complete ionic equation?
To represent each substance by its predominat form in the reaction mixture.
Example: If the substance is a soluble ionic compound, it probably dissolves as individual ions.
What is a complete ionic equation?
A chemical equation in which strong electrolytes are written as separate ions in the solution.
What are spectator ions?
An ion in an ionic equation that does not take part in the reaction. These can be cancelled from both sides of the equation.
What is the net ionic equation?
An ionic equation from which spectator ions have been canceled.
What are the three major types of reactions we will study in Chem 1040?
Although there are many millions of reactions and substances. The major types of reactions are:
- Precipitation reactions
- Acid-base reactions
- Oxidation-reduction reactions
What is a precipitate?
An insoluble solid compound formed during a chemical reaction in a solution.
What is an acid-base indicator?
A dye used to distringuish between acidic and basic solutions by means of the colour changes it undergoes in these solutions.
What is the early definition of an acid?
A substance that produces hydrogen ions, H+, when it dissolves in water.
What is the early definition of a base?
A substance that produces hydroxide ions, OH-, when it dissolves in water.
What is Bronsted and Lowry’s contemporary definition of an acid?
Species that donates a proton to another species in a proton transfer reaction
What is Bronsted and Lowry’s contemporary definition of an base?
The species (molecule or ion) that accepts a proton in a proton-transfer reaction.
What is a strong acid?
An acid that ionizes completely in water; it is a strong electrolyte.
What is a weak acid?
An acid that only partly ionizes in water; it is a weak electrolyte.
What is a strn base?
A base that is present in aqueous solution enittrely as ions, one of which is OH-; it is a strong electrolyte.
What is a weak base?
A base that is only partly ionized in water.
What is a neutralization reaction?
A reaction of an acid and a base that results in an ionic compound and possibly water.
What do most neutralization reactions result in?
They result in a salt.
What are monoprotic acids?
Acids that only have on acidic hydrogen atom per acid molecule.
What is a polyprotic acid?
An acid that yields two or more acidic hydrogens per molecule.
What are oxidation reduction reactions?
Reactions involving a transfer of electrons from one species to another.
What is a principal of oxidation numbers?
An oxidation-reduction reaction is one in which one or more atoms change oxidation number, implying that there has been a transfer of electrons.
What is a half-reaction?
One of two parts of an oxidation-reduction reaction, one part of which involves a loss of electrons and the other a gain of electrons.
Oxidation is the half-reaction in which there is a loss of electrons by a species.
Reduction is the half-reaction in which there is a gain of electrons by a species
What is a combination reaction?
A reaction in which two substances combine to form a third substance. All combination reactions are oxidation-reduction reactions.
What are the most common forms of oxidation-reduction reactions?
- Combination reaction
- Decomposition Reaction
- Displacement Reaction
- Combustion reaction.
What is a decomposition reaction?
A reaction in which a single compound reacts to give two or more substances. (These often occur when the temperature is raised)W
What is a displacement reaction?
A reaction in which an element reacts with a compound, displacing another element from it.
What is a combustion reaction?
A reaction in which a substance reacts with oxygen, usually with the rapid release of heat to produce a flame.
