Chapter 14
strong electrolyte
an aqueous solution that is a good conductor of electricity (high ion content)
weak electrolyte
an aqueous solution that is a poor conductor of electricity (low ion content)
acid
any substance that releases hydrogen ions H^+, into water
Brønsted-Lowry definition of acids and bases
are broader than that of Arrhenius definitions
acid solutions
are standardized by neutralizing a weighed quantity of a solid base.
acidic solution ph
as a solution becomes more acidic the ph decreases
basic solution ph
as a solution becomes more basic the ph increases
bases
bitter taste ex.milk of magnesia
basic solutions turn what color with litmus paper
blue
what color does the litmus paper turn in the presence of hydroxide ions
blue
what color does the litmus paper turn when there is an acid present
blue
how is the strength of an Arrhenius base measured
by the degree of dissociation in solution
how is the strength of an Arrhenius acid is measured?
by the degree of ionization in solution
endpoint
when the ph increases above 7, phenolphthalein changes from colorless to pink indicating the endpoint of the titration
do acids have varying strengths
yes
do bases have varying strengths?
yes
ionization constant of water at 25 celsius
1.0x10^-14
process of titration
a measured volume of base is added to the acid solution. When all of the acid has been neutralized the phis 7. One extra drop of the base solution after the endpoint increases the ph.
standard solution
a solution in which the concentration is known precisely
acid-base indicator
a solution that is sensitive to a change in ph by exhibiting a different color
Arrhenius acid
a substance that ionizes in water to produce hydrogen ions ex. HCL
Arrhenius base
a substance that ionizes in water to release hydroxide ions ex. NaOH
amphiprotic compounds
a substance that is capable of both donating and accepting a proton ex. H2O & NaHCO3
lithium hydroxide LiOH strong or weak base
dissociates 100%/ strong
barium hydroxide Ba(OH)2 strong or weak base
dissociates 100%/strong
calcium hydroxide Ca(OH)2 strong or weak base
dissociates 100%/strong
potassium hydroxide KOH strong or weak base
dissociates 100%/strong
sodium hydroxide NaOH strong or weak base
dissociates 100%/strong
strong bases dissociate
extensively to release hydroxide ions into solution ex. NaOH strong base nearly dissociates 100%
hydronium ion H3O^+
formed when a hydrogen ion attaches to a nonbonding electron pair on a water molecule
strong bases dissociate
fully and weak slightly
titration problem
given mL acid*molar/concentration*mole ratio*molarity/concentration=mL base
ph value of a base
greater than 7
acidic solution
has a ph less than 7
neutral solution
has a ph of 7
weakly acidic solutions
have a ph between 2 and 7
weakly basic solutions
have a ph between 7 and 12
strongly basic solutions
have a ph greater than 12
strongly acidic solutions
have a ph less than 2
neutral solutions
have a ph of 7
acids
have a sour flavor (including lemons, limes, and vinegar)
Arrhenius acids have
hydrogen atom bonded to an acid molecule by polar bond. This bond breaks down whe nth e acid ionizes.
strong acids ionize extensively to release
hydrogen ions into a solution ex. HCl is strong acid and ionizes nearly 100%
concentration of hydrogen ions [H^+]
in pure water is 1x10^-7 mol/L at 25 celsius
Hydrochloric acid HCL acid strong or weak?
ionizes 100% /strong
HNO2 nitric acid acid strong or weak
ionizes 100%/strong
sulfuric acid H2SO4 strong or weak acid
ionizes 100%/strong
buffer
is a solution that resists changes in ph when an acid or base is added a buffer is a solution of an aqueous weak acid and one of its salts ex. citric acid and sodium citrate make a buffer solution
base
is a substance that releases hydroxide ions OH^- into water
ph value of an acid
less than 7
neutralization reaction of an acidic solution and basic solution
make salt and water
ph
measure of acidity of a solution
what happens in acidic-basic reaction
neutralization occurs
can water react with water
no, pure water is a poor conductor
mathematically ph is
pH=-log[H^+] ex. [H^+] molar hydrogen ion concentration
a solution can be classified based on it's
ph
basic solution
ph greater than 7
Svante Arrhenius
proposed definitions for acids and bases
spectator ions
reactants that appear on both sides with same charge (are crossed off in net ionic equations)
acidic solution turns what color with a litmus paper
red
what color does litmus paper turn in presence of hydrogen ions?
red
what color does the litmus paper turn in the presence of a base?
red
ammonium hydroxide NH3OH strong or weak base
slightly dissociates/ weak
weak acids only ionize
slightly in solution ex. HF is a weak acid and ionizes only about 1%
weak bases only ionize
slightly in solution ex. NH4OH weak base partially dissociates
H3PO4 phosphoric acid
slightly ionizes/ weak
HC2H3O2 acetic acid strong or weak acid
slightly ionizes/ weak
hydrofluoric acid HF
slightly ionizes/ weak
H2CO3 carbonic acid weak or strong
slightly ionizes/weak
bases properties
slippery, soapy feel
soluble ionic compounds
strong electrolytes
strong acids and bases
strong electrolytes
Brønsted-Lowry base
substance that accepts a hydrogen ion it is a proton acceptor
Brønsted-Lowry acid
substance that donates a hydrogen ion to any other substance. it is a proton donor.
when an acid is added to the buffer
the citrate reacts with the acid to neutralize
when a base is added to the buffer
the citric acid reacts with the base to neutralize it
net ionic equation
the complete or total ionic equation that cancels out the spectator ions that are in the solution but do not participate in the overall reaction
the greater the degree of ionization or dissociation
the greater the conductivity of the solution
ionization
the process by which molecules of a polar compound ionize to form cations and anions ex. HCL ionizes into H^+ and Cl^- in solution
dissociation
the process whereby already existing ions of an ionic compound simply separate ex. NaOH dissociates into Na^+ and OH^-
if there is an acid with two hydrogens
then we need 2 hydroxide ions to neutralize it
when we dissolve arrhenius bases in a solution
they dissociate giving a cation and a hydroxide anion
indicators are used in
titrations
titration
used to analyze an acid solution using a solution of a base
ph scale
uses powers of 10 to express the hydrogen ion concentration
insoluble ionic compounds
weak electrolytes
weak acids and bases
weak electrolytes