Unit 9

Question 1

Arrhenius theory

Answer 1

-acids as chemicals that release (produce) hydrogen ions (H+) or protons when dissolved in water such as hydrochloric acid, HCl.
-Arrhenius bases release (produce) hydroxide ions (OH-) when dissolved in water like sodium hydroxide, NaOH.
-Water is the solvent when dissolving acids and bases for which the ions dissociate from each other to form either protons (hydrogen ions) for acids or hydroxide ions for bases.
-only metallic hydroxides can act as Arrhenius bases since they have hydroxide ions in their chemical formula. Thus, Arrhenius acids and bases are compounds that dissociate into ions when dissolved in water forming electrolytes that can conduct electricity.

Question 2

Brønsted-Lowry Acids and Bases

Answer 2

• acids: proton donor (acc electron ?)
  -base: proton acceptor (give up electron?)
  -Once an acid donates a proton it becomes a base, called a conjugate base.
  -When a base accepts a proton it becomes an acid, called a conjugate acid
  -In Brønsted-Lowry acid-base reactions, water does not have to be the solvent. In fact, water (H2O) either acts as an acid or base in the reaction.
• In aqueous acidic or basic solutions, water is an amphoteric substance acting as either an acid or base depending on whether it is in the presence of an acid or base
  -Water will act as a base in the presence of an acid and an acid in the presence of a base.
• If the base is negatively charged, its conjugate acid is neutral. When a neutral base accepts a proton, the conjugate acid has a positive charge.

Question 3

When acids and bases are mixed

Answer 3

a neutralization reaction occurs that forms a salt and water as the end products

Question 4

polyprotic acids

Answer 4

-acids that have more than one proton to donate in an acid-base reaction
-diprotic acids can donate two protons
-triprotic acids can donate three protons

Question 5

Blue litmus paper

Answer 5

can identify acidic solutions be turning red in the presence of acids

Question 6

Red litmus paper

Answer 6

turns blue in the presence of bases

Question 7

Acids and bases

Answer 7

Acids have a distinctive sour taste
Bases are slippery, bitter taste

Question 8

Arrhenius Acids ex

Answer 8

HF
HCl
H2SO4
HNO3

Question 9

To write conjugate acid
To write conjugate base

Answer 9

Increase H by 1, increase charge by 1 (acid)
Decrease H by 1, decrease charge by 1 (base)

Question 10

Reactions of acids with bases
Ex.

Answer 10

-Acids can react w metals to produce hydrogen gas (H2)
-Acids can react with ammonia to form ammonium salts
-Amines react with acids just like ammonia to form soluble salts.

Question 11

acid-base neutralization
(Arrhenius bases react with acid to form water and salts)

Answer 11

-Acids and bases react with each other to make water and a salt
-Salts are ionic compounds produced from double replacement (displacement) reactions between aqueous acidic and basic solutions.

Question 12

For acid-base equilibria, the favored reaction will be the direction

Answer 12

-in which the strongest acid and base react to form a weak conjugate base and conjugate acid, respectively
-The stronger the acid, the weaker it’s conjugate base will be. The stronger a base, the weaker it’s conjugate acid is.

Question 13

Acids and bases

Answer 13

Question 14

strong Arrhenius bases

Answer 14

-Many hydroxides of alkali metals (NaOH) and alkaline earth metals (CaOH2) are strong Arrhenius bases that will easily accept a proton from weak acids such as water.
-Even though some o hydroxides of alkaline earth metals are only slightly soluble, they are still strong bases that form hydroxide ions easily when they react with acids.

Question 15

Acid and base in pure water

Answer 15

When an acid is added to pure water, it will react with water molecules to form hydronium ions. When a base is added to pure water it will react with water molecules to form hydroxide ions.
-‘The ability of water to act as a base (accepting protons) or an acid (donating protons) depends on the presence of a stronger acid or base respectively, making water an amphoteric substance.
-the acidity and basicity of a solution is based on the ratio of hydronium to hydroxide ions.

Question 16

Kw
Equilibrium constant for water

Answer 16

Kw = [H3O+][OH-] = 1.0 x 10-14
In PURE water concentration of H3O+=OH- concentration (it is NEUTRAL)
H3O+>OH- acidic
OH->H3O+ basic

Question 17

Autoionization

Answer 17

Water acting as both an acid and a base when by itself

Question 18

pH

Answer 18

pH= -log(H3O+)
pH + pOH =14 (at 25^C)
pOH = -log [OH-]
[OH-] = 10^-poH
[H3O+]=10^-pH
pKa= -log [ka]
pKb= -log [kb]
pKa + pKb =14
[OH-]=1x10^-14/[H3O+]
Ka=10^-pKa
Kb=10^-pKb
Ka x kb = 1x10-14

All concentrations must be in molarity when doing pH and pOH calculations.

Question 19

Buffers

Answer 19

-Solutions that can resist pH changes when strong acids or bases are added to them.
-The most common buffers are mixtures of weak acids and the salts of their conjugate bases.
-alternately, a buffer can be composed of the salt of a weak base and its conjugate acid. A good buffer has equal concentrations of the weak acid or base and their conjugates.