Lab 3- PH Measurements Flashcards
(17 cards)
What type of reaction do strong acids/bases describe? What about weak acids/bases?
Strong acids and bases describe a reaction in which the equilibrium favors the products and weak acids and bases describe a reaction in which the equilibrium favors the reactants.
What is an Arrhenius Acid/Base?
Arrhenius acid produces H+ ions in aqueous solutions and Arrhenius bases produces OH- in aqueous solutions.
What is a Brønsted-Lowry Acid/Base?
The acid is the proton donor and the base is the proton acceptor.
What is a Lewis Acid/Base?
A Lewis acid is the electron pair acceptor and the leis base is the electron pair donor.
Why is the Arrhenius model considered to be limited?
Because it only applies to aqueous solutions and it allows for only one type of base.
Define Amphoteric; what is an example?
Amphoteric means something can act as an acid and or a base; an example is water.
Define Autoionization of Water
When one water molecule reacts with another molecule of water to produce hydronium and hydroxide.
What is the formula for Kw?
[OH-][H3O+]=1.0x10^-14
What is something that can affect the value of Kw (the ionic product constant for water)?
It varies according to the temperature at which it is measured.
What is the equation involving the addition of pH and pOH AT ROOM TEMPERATURE?
pOH+pH=14.00
What is something to consider regarding the fluctuation of concentrations of hydronium and/or hydroxide?
If the hydronium ion concentration is increased, then the hydroxide ion concentration must decrease, and vice versa.
What is a definition for weak acids and bases?
Acids and bases that do not undergo substantial ionization in water are said to be weak.
Acetic acid is a weak acid, therefore not much of it dissociates. But what would happen if we dissolved acetic acid in an aqueous solution of sodium acetate instead of pure water?
Increasing the concentration of one of the products (CH3COO-), the equilibrium will shift to offset this change by forming more reactants. Therefore, less of the acetic acid will dissociate.
Define Indicator
A weak acid that undergoes a color change when it is converted into its conjugate base.
What conclusion can be reached if the equilibrium is predominantly to the left/right respectively in the case of indicators being present?
If an indicator’s equilibrium is predominantly to the left (meaning the concentration of the weak acid is greater than that of the conjugate base), then the color of the weak acid will be exhibited; if an indicator’s equilibrium is predominantly to the right (meaning that the concentration of the weak acid is less than that of the conjugate base), then the color of the conjugate base will be exhibited.
How can comparing the value of the hydronium concentration to the Ka value (ionization constant for a weak acid) help us determine whether the color of the weak acid or conjugate base will be exhibited?
If [H3O+]»_space; Ka, then the concentration of the weak acid is greater than that of the conjugate base by at least a factor of 10 and the color of the WEAK ACID is observed.
If [H3O+] is approximately the same for Ka, then the same is true regarding the concentrations of the weak acid and the conjugate base; A MIX OF BOTH COLORS WILL BE EXHIBITED.
If [H3O+] «_space;Ka, then the concentration of the conjugate base is greater than that of the weak acid by at least a factor of 10 and the color of the conjugate base is observed.
How can we determine the exhibited colors through comparing the pH and pKa values?
If pH<pKa-1, the color of the weak acid will be exhibited.
If pH is approximately the same as the pKa, then the mix of both colors will be exhibited.
If pH> pKa +1, then the color of the conjugate base will be exhibited.
