Chapter 16 Quest

*not finished

Arrhenius acid definition

increase [H⁺]in aqueous solution

Arrhenius base definition

increase [OH^-] in aqueous solution

Arrhenius acid-base equation

acid + base → salt + water

Bronstead-Lowry acid definition

donates H⁺

Bronstead-Lowry base definition

accepts H⁺; does not need to contain OH^-

Amphiprotic

any molecule or ion that can gain or lose a proton; can behave as acids and bases

Amphoteric

reserved for insoluble oxides that dissolve in acidic or basic solutions; can behave as acids and bases

How to determine concentration of hydronium/hydroxide?

pOH = -log[OH^-] or pH₃O = -log[H₃O]

K_w

ion-product constant of water; autoionization of water; 1 × 10^-14

K_w »

more water molecules are ionizing; a more basic or acidic solution

K_w «

only a very small amount of water molecules are ionizing; predominately neutral solution

K_w with temperature

increases with increasing temperature; more water molecules ionize at higher temperatures

What conditions makes the autoionization of water a source of H⁺?

at 25 degrees C

Conjugate base

whatever is left of the acid after the proton is donated

Conjugate acid

whatever remains of the base after it accepts a proton

Conjugate acid-base pairs differ by

one proton

7 Strong Acids

HCl, HBr, HI, HNO₃, HClO₃, HClO₄, and H₂SO₄

6 strong bases

group 1 hydroxides: LiOH, NaOH, KOH, RbOH, CsOH; heavy group 2 metal hydroxides: Ca(OH)₂, Sr(OH)₂, Ba(OH)₂

How do you calculate pH and pOH from strong acid and base concentrations?

put the strongest acid concentration into the pH equation (if acid M < 10^-6 M then pH = initial molarity) and the strongest base concentration into the pOH equation

How can you use conjugate pairs to classify acids/bases as strong or weak?

stronger acid, negligible conjugate base; weak acid, weak conjugate base; negligible acid, strong base

Leveling effect of water

places strong acid/base in dilute acetic acid to find different in their strengths; H⁺ is strongest acid and OH^- is strongest base in equilibrium in aq

Equilibrium in acid-base reactions

favors transfer of proton from stronger acid to stronger base; strong acid → favors right side and weak acid → favors left side- bc favors weak electrolyte production

Acidic Solutions

[H⁺] > 1.0 × 10^-7 and pH < 7.00

in neutral water at 25C, pH =

pH = pOH = 7.00

basic solutions

[H⁺] < 1.0 × 10^-7 and pH > 7.00

pH/pOH sig figs

use concentration’s sig fig (what you take the log of)

K_a » in terms of acids

stronger the acid

K_a > 1 in terms of acids

acid is a strong acid and is completely ionized

What does pH give?

the equilibrium concentration of H⁺

If you have an K_a or K_b value of 10^-5 or less, you can

usually make an assumption; make sure to double check though

Percent ionization

[H₃O⁺]_eqm / [HA]₀ × 100 or [OH^-]_eqm / [A^-]₀ × 100

What does a higher percent ionization mean?

stronger the acid

Percent ionization of a weak acid decreases as the molarity

increases

If the successive K_a values differ by a factor of _____ or more, pH can be determined by considering only ___

10³; K_a1

weak acids are only

partially ionized