Section 15.5- pH Flashcards
pure water ____________ ionize
does (to a small extent)
equilibrium constant expession
K sub w = [? +] [? -]
the equilibrium constant (Ksubw) is called the
ion-product constant of water
like other equilibrium constants, Kw varies with
temperature
in ___________ solutions, the concentrations of H3O+ and OH- are equal
neutral (like pure water)
a solution in which hydronium ions predominate (H3O+ is greater than 1.00 x 10 ^-7 M)
acidic solution
a solution in which hydroxide ions predominate (OH- is greater than 1.00 x 10^-7 M)
basic solution
scale that measure the power of hydrogen
pH scale
if the pH scale is 0-6
acidic
if neutral, pH is
7
if the pH scale is 8-14
basic
a more convenient way to represent the H3O+ concentration is the
pH scale
the pH of a solution is defined as the
- log of the hydronium ion molarity
equation for determining pH
pH= - log [H3O+]
simply another way to express a number as a power of 10
logarithm
to find the pH of a given solution, simply find the logarithm of [H3O+] in that solution and
change the sign
in a logarithm, only the digits to the ______________________ count as significant figures
right of the decimal point
the OH- concentration may be expressed using
pOH
the pH and pOH scales are closely related; in any aqueous solution at 25 C, the sum of the pH and pOH is
14
pH + pOH= 14
the pH of a solution is most conveniently measured by an electronic
determines pH of a solution by precisely measuring the electric current generated when a pair of special electrodes are immersed in the solution to be tested
pH meter
less precise pH value may be obtained by using
organic acids or bases whose color changes with the pH of the solution
acid-base indicators
the best-known indicator is
an organic dye that is Blue in Basic solutions and reD in aciDic solutions
litmus
high concentrations of H3O+ tend to suppress the ionization of the indicator, keeping it largely
nonionized (Le Chatelier’s Principle)
color of the acid form thus predominates
ways to obtain approximate pH values include
universal indicator
pH paper
a mixture of several indicators that imparts a characteristic color to the solution over the whole range of pH values
universal indicator
