EXERCISE 1 - 2 Flashcards
- almost all processes containing ____ have a need for pH measurement
WATER
compares the acidity or alkalinity of a solution at a given temperature
pH
neutral pH
pH 7
pH can only be measured if it is in ____ form
AQUEOUS
pH measures the dami ng
H+
neutral solution activity
H & OH are equal
acidic
ph < 7
acidic soln activity
H activity ↑ ; pH value ↓
basic
pH > 7
basic soln activity
OH activity ↑ ; pH value ↑
H activity and pH is
inversely proportional
the acidity and basicity of a substance can be measured in terms of
MOLAR CONCENTRATION
to provide ease in expressing these values, the concentration and OH- ions are denoted as
pH and pOH
the pH of a solution may be measured using
pH paper
measured the pH of the solution by changing its color depending on the concentration of H and OH ions
pH paper
pH paper is treated with an indicator known as
FLAVIN
flavin is an ____ commonly found in red cabbages
ANTHOCYANIN
flavin usually turns:
solution is acidic
RED
flavin usually turns:
solution is neutral
GREEN
flavin usually turns:
solution is basic
PURPLE
- more accurate method than pH paper
- contains a probe that passes the electrical signals to the meter itself which interprets the electrical signals and display the results on its screen
pH meter
two electrodes of ph meter
sensor
reference
contains a pH 7 buffer
sensor electrode
usually contains saturated KCl solution
reference electrode
made up of porous glass; have both a silver wire covered with silver chloride or calomel
PROBE
pH meter probe has a silver wire that is covered with
silver chloride or calomel
- H ions are spontaneously generated in pure water by the dissociation (ionization) of a small percentage of water molecules
- dissociation makes equal numbers of H and OH ions
- while the OH ions can float around in solution as themselves, the H ions are transferred directly to a neighboring water molecule to form hydronium ions
AUTOIONIZATION OF WATER
AUTOIONIZATION OF WATER
H+ spontaneously ____ to form H+ and OH- equally
DISSOCIATES
the ____ of H+ causes it to bind to another H2O molecule, thus forming a hydronium ion
REACTIVITY
AUTOIONIZATION OF WATER
The amount of dissociative H+ is ____ to the amount of H3O+ formed.
EQUAL
- Acids are species that increase [H+]
- Bases are species that increase [OH-]
- Limited in describing acidity and basicity to dissociation in aqueous solution
ARRHENIUS
ARRHENIOUS
Many substances behave as an acid or base in ____ phase where no solvent is present
GASEOUS PHASE
● Acids are proton donors
- Must have a H+ that can
dissociate
● Bases are proton acceptors
- Must have at least one pair of electrons to form a bond with a proton
BRONSTED-LOWRY
BRONSTED
react almost completely with water
STRONGER ACIDS
inorganic acids
react only slightly with water
WEAK ACIDS
acetic acid
Acid strengths are given using what values
pKa
acid dissociation constant
Ka
gives the exact strength of acid in water
Ka
acid dissociation constant
There is an ____ relationship between Ka and pKa
INVERSE
- Acids accept a pair of non-binding electrons
- Bases donate a pair of non-binding electrons
- Suggest that sharing electrons between acids and bases causes no change in the oxidation numbers of any atoms.
LEWIS
Provided a way of simplifying the expression of [H+]
SORENSEN
pH means
pruissance d’ hydrogen
pruissance d’ hydrogen means
POWER OF HYDROGEN
how to compute for pH & pOH
-log [H+]
-log {OH-]
how to compute for [H+] [OH-]
10‾pH
10‾pOH
formula for pKw
pKa + pKb = 14
pH + pOH = 14
- Resist change in pH
- Most organisms, including humans, need to maintain pH within a fairly narrow range to survive
- Consists of an acid-base pair, with the acid and base differing by the presence or absence of a proton (conjugate acid-base pair)
BUFFERS
BUFFERS
human blood involves what acid
CARBONIC ACID
H₂CO₃
BUFFER
conjugate base of the human blood
BICARBONATE ION
HCO₃‾
Used to calculate the pH of a buffer system
HENDERSON-HASSELBALCH
formula for buffer, weak acids
pH = pKa + log (salt/acid)
formula for buffer, weak bases
pH = pKw - pKb + log (base/salt)
