Acids and Bases

Ionization of Water Only happens to a small amount of water

molecules H2O separates into ______________ Not the whole story

H+ never occurs on its own In reality, another H2O molecule picks it up and

becomes ___________________

Acids and Bases

Acids Bases

Taste sour Taste bitter

Feel watery Feel slippery

Conduct electricity Conduct electricity

Change litmus to red Change litmus to blue

pH = 0-7 pH = 7-14

Neutralize bases Neutralize acids

Classifying Acids and Bases Arrhenius

Acid- substance that dissociates into ______________ For Example: ___________________

Base- substance that dissociates into ______________ For example: __________________

Does not explain bases without an OH ion

Classifying Acids and Bases (cont) Brønsted-Lowry

Acid - _______________ For example: HCl and H2SO4

Base - ________________ For example: NH3 and OH-

Conjugate Acid and Bases Occur on the other side of acid base equations. Lets look again at

NH3 is a ________. It will accept a proton (H+) H2O is an _______. It will donate a proton (H+) NH4

+ is NH3’s _____________. It can donate a proton (H+) to become NH3 again

OH- is water’s ______________. It can accept a proton (H+) to become H2O again

Amphiprotic Amphiprotic –

Substances that can act like an acid or a base Water is an amphiprotic substance.

H2O can accept a proton to become H3O+

H2O can donate a proton to become OH-

Strength of Acids and Bases Depends on how much they dissociate in

water Strong

Considered to dissociate _____________ in water Weak

Only partially dissociate in water Reaction is _____________________

Conjugate pairs Strength is ______________________

For example: Strong acids have weak conjugate bases

Acids Strong acids

________ ________ ________ ________ ________ ________ ________ All have 100% of the molecules

break apart. There is no reverse reaction.

Weak acids All others

Polyprotic Acids Have multiple ______ H2SO4

H2SO4 gives up 1 H+ to form HSO4-

This happens to ______ of the molecules since H2SO4 is strong

HSO4- gives up another H+ to form SO4

-2

This only happens to some HSO4- because it is _______

Solution will contain _________ of water molecules H3O+ molecules (mostly from the first H+ but some from the

second and from ionization of water) HSO4

-

a little bit of SO4-2

A little bit of OH- (from the ionization of water)

Acid Names Binary acids (______________)

Prefix __________ Root of element name Suffix ___________ Add acid For example: HCl is ___________________

Acids with Oxygen (_________________) Root name of polyatomic (with polyatomic prefix if applicable)

Some polyatomic roots are modified slightly to be easier to say Suffix

-ic with polyatomics ending in _______ -ous with polyatomics ending in _______

Add acid For example: H2SO4 is ______________

Bases Strong bases

Group 1 metals with OH-

Ca, Sr, and Ba with OH-

These three are not very soluble in water, but the amount that does dissolve ionizes completely.

Weak bases All others

Chemical Equilibrium Reversible reactions Indicated with a _________

Both reactions are happening at the same time System reaches equilibrium when both are happening at

same _____ At equilibrium

Could have lots of reactant and little product Could have lots of product and little reactant Could have equal amounts of both

Changes to the system can shift equilibrium Temperature Pressure Adding reactants or products

Equilibrium Expressions Mathematical way to represent equilibrium For the equation, ________________________

K = [C]c [D]d

[A]a [B]b

K is the equilibrium constant for the equation [ ] indicates the concentration of each substance

in mol/L (M) _______________ are not entered into the expression

Ionization of Water 2H2O(l) H3O+(aq) + OH-(aq)

This equilibrium ___________________ In other words, there is far more water molecules than

hydronium and hydroxide ions in a sample

Kw = ________________ Kw = 1.0 x 10-14

In pure water and neutral solutions, [H3O+] and [OH-] are 1.0 x 10-7 M

In acidic solutions, ____________________________ In basic solutions _____________________________

pH pH

Stands for potential of Hydrogen (really hydronium)

______________ scale pH = -log [H+] or [H+] = 10-pH

Values between 0-14 with each number representing a 10-fold increase from the previous number pH 7 is ________ pH = 7 is ________ pH 7 is ________

pOH pOH = -log [OH-] or [OH-] = 10-pOH

Opposite scale pOH 7 is ________ pOH = 7 is ________ pOH 7 is _________

Indicators Compounds that change color in the presence

of different levels of pH

Soil pH 6.0-6.5

Soil pH 5.0-5.5

Neutralization (Acid-Base Reaction) Special type of double displacement reaction Acid + Base ___________________

Titration Process of neutralizing an acid (or base) with an

unknown concentration with a base (or acid) of a known concentration

Moles of H3O+ must equal moles of OH- for neutralization to occur

Often indicators are used to determine the end of the reaction

VaMa = VbMb

Va = volume in L of acid Ma = molarity of acid Vb = volume in L of base Mb = molarity of base