10 Flashcards
Hydration
- positive ends of water molecule are attracted to negatively charged anions
- negative ends are attracted to positively charged cations
- this happens when water has salt or something in it
- it breaks up INDIVIDUAL cation and anions
Solubility
- ability of a substance to dissolve into a solvent
- differences in solubilities of IONIC compounds in water depends on relative attractions of the ions for each other (forces hold the solid together) and attractions of ions for water molecules
- all NITRATES are soluble in water
- water can dissolve NONIONIC substances
- in general, polar and ionic substances are expected to be more soluble in water than nonpolar substances
Solute
-substance being dissolved
Solvent
-substance dissolving the solute (water)
Electrical conductivity
-ability to conduct an electric current
Electrolyte
-substance that when dissolved in water produces a solution that can conduct electricity
Svante Arrhenius
- believed that the conductivity of solutions arose from the presence of ions (how many ions they created in aqueous solutions)
- believed acids provide a hydrogen ion (positive, H+) and are sour
- believed bases provide a hydrogen ion (negative, OH-)
Strong Electrolytes
- there are three classes : soluble salts, strong acids, strong bases
- salt (cations and anions) separate in water
Strong Acids
- when they are in water, virtually every molecule ionizes
- sulfuric acid, nitric acid, and hydrochloric acids are aqueous and should be written like HCl(aq)
- since strong acids completely dissociate into its ions, 100 molecules of HCl dissolved in water will created 100 H+ ions and 100 Cl- ions
- H2SO4 says that this acid can produce 2 H+ ions per molecule when dissolved in water, but only the first H+ ion is completely broken down. The second H+ ion can be pulled off under certain conditions. Therefore, H2SO4 contains mostly H+ and H2SO4- ions.
Strong Bases
- soluble ionic compounds
- have hydroxide ion (OH-)
- when in water, OH- ions separate and move independently
- bitter and slippery
List of Strong Acids
- HCl, hydrochloric
- H2SO4, sulfuric
- HBr, hydrobromic
- HI, hydroiodic
- HNO3, nitric
- HClO4, perchloric
Weak Electrolytes
- acetic acids is a weak acid
- ammonia is a weak base
Acetic Acids:
- formula for acids are often written with acidic hydrogen atoms or atoms (produce H+ ions) first and non acidic hydrogens later
- double arrow means that the reaction can occur in either direction
- it is a weak acid
Weak Acid
-any acid that dissociate (ionizes) only to a slight extent in an aqueous solution
Weak Base
- ammonia is one
- resulting solution is a weak electrolyte (few ions are formed)
- OH- ions are also formed
Nonelectrolytes
- substances that dissolve in water but do not produce any ions
- ethanol is one (molecules do not break up into ions)
- table sugar (sucrose)
Molarity
- number mol solute/liters of solution
- measure of concentration
Solubility rules:
- all nitrates are soluble (NO3-)
- all alkali metals and ammonium salts are soluble (NH4+) (first column)
- all chlorides, bromides, and iodides are soluble except : Pb2+, Ag+, Hg2+
- all sulfates (SO42-) are soluble except Pb2+, Ag+, Hg22+, Ca2+, Sr 2+, Ba2+
- everything else is not soluble unless mr. william tells us otherwise
Spectator ions
things that don’t react
List of Strong Bases:
- LiOH
- NaOH
- KOH
- Ca(OH)2
- SR(OH)2
- Ba(OH)2
Three types of reactions
- double displacement/precipitation reaction
- acid base reaction / water forming
Double displacement/precipitation reaction:
- characterized by AX + BY –> AY + BX
- switching partners
Acid base reaction / water forming
- acid and base combining
- characterized by AX + BY –> AY + BX, like double displacement
- creates water
net ionic equation
crossing out spectator ions
formal equation
you show the switching
complete ionic eqution
formal with adding together
oxidation
loss of electrons
reduction
gain of electrons
positive charge getting lost
oxidation state
charge on the atom, works only for ionic not molecular
rules of oxidation state
- everything by itself in natural occurring state has a O charge
- oxygen COMPOUNDS are always 2- EXCEPT in peroxide (H2O2) where it is 1-
- hydrogen is always 1+ unless you are told otherwise
- everything else can be deduced from what you know
N
can be expressed as 10 to the X
ex:
- 100 is x = 2
- 10 is x = 1
using Log
LogN = x ex: -65 is x = ? -Log65 = x = 1.81
[A]
concentration of “A’ in molarity
ex:
[H+] is the concentration of H+ in molarity
to find the pH using log
pH = -log[H+] ex: 1. find concentration of H+ 2. the concentration of H+ is the same as HCl which is 6 3. [H+] is 6 4. plug in
what is pH typically between
0 (acidic) - 14 (basic)
what is H30+
- it is the same as H+
- H+ is just a proton and very small
- H+ then just latches onto H20, creating H30+
in the classic titration lab..
we are just adding NaOH to get HCl nneutralized
-at a 1 to 1 ratio
using molarity to find moles
- n = mv
- na = mava
- nb= mbvb
- since na and nb are equal: mava=mbvb
- in the classic titration lab we are trying to find ma
Dilution
- adding water to achieve molarity desired for particular solution
- moles of solute after dilution = moles of solute before dilution
Precipitation Reaction / Double displacement
- when two solutions are mixed, an insoluble substance sometime forms / a solid forms and separates from the solution
- remember: when ionic compounds dissolve in water, the resulting solution contains the separated ions
slightly soluble
- tiny amount of solid that dissolve is not noticeable
- the solid appears to be insoluble to the naked eye
Formula equation
- shows reactants and products of reaction
- does not give correct picture of what actually occurs in the solution
complete ionic equation
- all substances that are strong electrolytes are represented as ions
- reveals that only some of the ions participate in the reaction
- spectator ions are written as separate ions
- but solids are not written as separate ions
net ionic equation
-only shows solution components directly involved in the reaction
Solving Stoichiometry Problems for Reactions in Solutions
- identify species present in the combined solution, and determine what reaction occurs
- write balanced net ionic equation for reaction
- calculate moles of reactants
- determine which reactant is limiting
- calculate moles of product or products
- convert to grams or other units
indicator
- equivalence point or stoichiometric point is marked by this
- it changes color at the equivalence point
endpoint
-the point where the indicator actually changes color
Requirements for a successful titration
- the exact reaction between titrant and analyte must be known (and rapid)
- the stoichiometric point must be marked accurately
- volume of titrant required to reach stoichiometric point must be known accurately
covalent bonds
-electrons are shared
cations
positive
anions
negative
electrolytes
substances that conduct electricity when dissolved in whatever
