Studied by 21 people
What is the oxidation number of I- ?
-1 (ox number has to equal charge on molecule)
Do coefficients affect oxidation numbers?
No
What is the same among all the halogens?
They’re all diatomic
Stock solution
original more concentrated solution (M₁V₁)
Why do ions increase conductivity
ions carry electrical charge from one electrode to the other, completing a circuit
Conductivity and solubility of sugar
It can dissolve in water to create a uniform mixture, but the molecule doesn’t dissociate, so it’s not conductive
Strong acids and bases completely…
dissociate
Strong acids
Hydrochloric acid, HCl Hydrobromic acid, HBr
Hydroiodic acid, HI Chloric acid, HClO3
Perchloric acid, HClO4 Nitric acid, HNO3
Sulfuric acid, H2SO4
Strong bases
Group 1A metal hydroxides (LiOH, NaOH, KOH, RbOH, CsOH)
Heavy group 2A metal hydroxides [Ca(OH)2, Sr(OH)2, Ba(OH2)]
*Most bases are weak*
Acids and bases are either…
weak or strong electrolytes (never nonelectrolytes)
All acids are…
molecular but dissociate in water
Dissolution
to dissolve
Dissociation
breaking up into ions
When NaCl dissolves in water, dissociated sodium ions are said to be…
solvated (surrounded by oxygen atoms in water molecules)
molecular bond
nonmetal + nonmetal or metalloid + nonmetal
ionic bond
metal + nonmetal
Ionic compounds form…
electrolytes in water
Solubility does not equal…
conductivity
Solution
a homogenous mixture of two or more substances
Homogeneous mixtures have a…
constant composition
Aqueous solution
a solution in which water is the dissolving medium (solvent)
Electrolyte
a substance whose aqueous solutions contain ions, and can thus conduct electricity
Nonelectrolyte
not conductive due to no ions in solution
Solvation
process in which a solute is dissolved in a solvent to form a homogeneous mixture; ions dissociate
Ionization
when ions dissociate into their cation and anion
Most molecular compounds are…
nonelectrolytes, except for some acids
Strong electrolytes
solutes that exist in solution completely or nearly all as ions; all water soluble ionic compounds
Weak electrolytes
solutes that exist in solution mostly in the form of neutral molecules with only a small fraction in the form of ions
Weak electrolytic equations have…
double arrows to show chemical equilibrium (strong electrolytes only have 1 arrow)
Precipitate
an insoluble solid formed by a precipitation rxn in solution
Precipitation rxns occur when…
pairs of oppositely charged ions attract each other so strongly that they form an insoluble ionic solid
Solubility
the amount of substance that can be dissolved in a given quantity of solvent at the given temperature
How to predict if a precipitate will form
Note the ions present in the reactants
Consider the possible cation-anion combos
Use solubility rules to determine if any of these combos are insoluble
Precipitation and neutralization rxns
exchange (metathesis) reactions; double replacement
AX + BY → AY + BX
Molecular equation
full chemical formulas w/out indicating ions
Complete ionic equation
soluble, strong electrolytes are separated into ions; rebalance by distributing coefficients and subscripts into ions
Net ionic equation
when spectator ions are omitted from the equation; includes only the ions and molecules directly involved in the rxn
Spectator ions
ions that appear in identical forms on both sides of a complete ionic equation; play no direct role in the rxn
How to write net ionic equations
Write a balanced molecular equation
Write the complete ionic (only strong electrolytes dissolved in solution are written in ionic form)
Identify and cancel spectator ions
Acids
substances that ionize in aqueous solution to form hydrogen ions H+ (aq); because a hydrogen atom consists of a proton and an electron, H+ is simply a proton; acids are proton donors
Monoprotic acids
yield one H+ per molecule of acid (HCl, HNO3)
Diprotic acid
yield two per molec (H2SO4)
Ionization of sulfuric acid occurs…
in two steps:
H2SO4 → H + HSO4
HSO4 ⇌ H + SO4
In acetic acid…
only one H is broken off the oxygen (CH₃COOH)
Bases
substances that accept (react with) H+ ions. Bases produce hydroxide ions when they dissolve in water. Ionic hydroxide compounds, NaOH, KOH, and CO(OH)2, are the most common.
Compounds that don’t contain OH can also be bases (ammonia NH3). When added to water ammonia accepts an H+ ion from a water molecule to produce an OH- ion from water.
Examples of strong electrolytes
ionic compounds, strong acids and bases
Examples of weak electrolytes
weak acids and bases
Neutralization rxn
when a soln of an acid and base are mixed to form water and a salt
Salt
any ionic compound whose cation comes from a base and whose anion comes from an acid
Main feature of any neutralization rxn
H+ and OH- combine to form H2O
Oxidation
when an atom, ion, or molecule becomes more positively charged, loss of electrons
Reduction
when an atom, ion, or molecule becomes more negatively charged, gain of electrons
Oxidation of metals by acids and salts
Displacement rxn; single replacement
A + BX → AX + B
Activity series
list of metals arranged in order of decreasing ease of oxidation
Active metals
The metals at the top (alkaline earth metals) are most easily oxidized; meaning, they react most readily to form compounds
Noble metals
The metals at the bottom (transition elements from groups 8B and 1B), are very stable and form compounds less readily
Any metal on the list can be oxidized by the ions of the elements…
below it
Higher element in series =
element that’s oxidized (loses electrons; increased ox #)
Concentration
the amount of solute dissolved in a given quantity of solvent or quantity of solution. The greater the amount of solute dissolved in a certain amount of solvent, the more concentrated the solution is.
Measured in molarity (number of moles of solute/liter of soln)
Molarity =
moles of solute / volume of solution in Liters
m = n/v
A 1 molar solution (1 M) contains…
1 mol of solute per liter of soln
The concentration of a dissociated ion is the same as its salt if the subscript is…
1 (if it’s anything greater multiply the subscript by the molarity of the whole molecule)
A 1.0 M soln of Na₂SO₄ is ___ in Na⁺ ions and ___ in SO₄²⁻ ions
2 M; 1 M
Molarity is a conversion factor between…
volume of soln and moles of solute
Dilution
When solutions of a lower concentration are obtained by adding water
Dilution equation
M (conc) x V (conc) = M (dil) x V (dil)
Titration
combining a solution where the solute concentration is not known with a reagent solution of known concentration, called the standard solution. Just enough standard soln is added to completely react w the solute in the soln of unknown conc.
Equivalence point
the point at which stoichiometrically equivalent quantities are brought together.
Nonmetals want to…
gain electrons (least likely to be oxidized)
In complete ionic equations, only ionize…
aqueous substances (do NOT ionize g, l, or s)
In neutralization reactions, do not ionize…
water, and the salt if it’s insoluble
In order for a single replacement reaction to work, the metal doing the replacing must be…
higher up on the activity series
