TEST 2 Flashcards
electrolyte
something that breaks down in water to form ions. strong if completely breaks down and weak if only breaks into a few.
non-electrolyte
dissolve to form neutral molecules. dont conduct electricity
are salts soluble
some soluble, some not
are soluble salts completely soluble or not?
they are completely soluble. So they are strong electrolytes
how do we know if a salt is soluble?
by checking the solubility table
are ions soluble?
yes. always. bc they are charged and water is polar
precipitation reaction
reaction b/w two aqueous solutions that yields one solid product. this happens when one of the products is an insoluble salt
molecular equation
shows neutral formula for each compound in aq reaction as if they existed as molecules
ionic equation
in solutions containing soluble ionic compounds the dissolved substances are present as ions so we include this info in the equation. make sure you move the subscripts!!
A precipitation reaction is
one in which dissolved substances react to form one (or more) solid products. Many reactions of this type involve the exchange of ions between ionic compounds in aqueous solution and are sometimes referred to as double displacement, double replacement, or metathesis reactions. These reactions are common in nature and are responsible for the formation of coral reefs in ocean waters and kidney stones in animals. They are used widely in industry for the production of a number of commodity and specialty chemicals. Precipitation reactions also play a central role in many chemical analysis techniques, including spot tests used to identify metal ions and gravimetric methods for determining the composition of matter
solubility
The extent to which a substance may be dissolved in water, or any solvent/ the maximum concentration of a substance that can be achieved under specified conditions.
soluble substances
Substances with relatively large solubilities
insoluble substances
Substances with relatively low solubilities are said to be insoluble, and these are the substances that readily precipitate from solution. A substance will precipitate when solution conditions are such that its concentration exceeds its solubility.
net ionic equation
ionic eq with spectator ions cancelled out.
spectator ions
ions that don’t undergo a change from a rxn
when is there no rxn
if none of the potential products are insoluble no reaction occurs.
acid-base reaction
a reaction in which a hydrogen ion, H+, is transferred from one chemical species to another.
acid
a substance that will dissolve in water to yield hydronium ions, H3O+
A base
a substance that will dissolve in water to yield hydroxide ions, OH−. The most common bases are ionic compounds composed of alkali or alkaline earth metal cations (groups 1 and 2) combined with the hydroxide ion. previously, these compounds do not react chemically with water; instead, they dissolve and dissociate, releasing hydroxide ions directly into the solution.
neutralization reaction
A neutralization reaction is a specific type of acid-base reaction in which the reactants are an acid and a base (but not water), and the products are often a salt and water
oxidation
loss of electrons
reduction
gain of electrons
oxidizing agent
the one thats reduced
reducing agent
the one thats oxidized
The oxidation number of an atom in an elemental substance is
zero.
The oxidation number of a monatomic ion is
equal to the ion’s charge.
Oxidation number for Hydrogen:
+1 when combined with nonmetals, −1 when combined with metals
Oxidation number for Oxygen:
−2 in most compounds, sometimes −1 (so-called peroxides, O22−),O22−), very rarely −12−12 (so-called superoxides, O2−),O2−), positive values when combined with F (values vary)
Oxidation number for Halogens:
−1 for F always, −1 for other halogens except when combined with oxygen or other halogens (positive oxidation numbers in these cases, varying values)
The sum of oxidation numbers for all atoms in a molecule or polyatomic ion equals
the charge on the molecule or ion.
Oxidation-reduction (redox) reactions are
those in which one or more elements involved undergo a change in oxidation number.
Single-displacement (replacement) reactions are
redox reactions in which an ion in solution is displaced (or replaced) via the oxidation of a metallic element. Metallic elements may also be oxidized by solutions of other metal salts
Balancing Redox Reactions via the Half-Reaction Method
- Write the two half-reactions representing the redox process.
- Balance all elements except oxygen and hydrogen.
- Balance oxygen atoms by adding H2O molecules.
- Balance hydrogen atoms by adding H+ ions.
- Balance charge by adding electrons.
- If necessary, multiply each half-reaction’s coefficients by the smallest possible integers to yield equal numbers of electrons in each.
- Add the balanced half-reactions together and simplify by removing species that appear on both sides of the equation.
- For reactions occurring in basic media (excess hydroxide ions), carry out these additional steps:
Add OH− ions to both sides of the equation in numbers equal to the number of H+ ions.
On the side of the equation containing both H+ and OH− ions, combine these ions to yield water molecules.
Simplify the equation by removing any redundant water molecules.
9. Finally, check to see that both the number of atoms and the total charges1 are balanced.
