Acids and Base Quiz Flashcards
(12 cards)
Acids VS Bases
Acids
- pH levels less than 7
- taste sour
- React with active metals(Mg,Zn) to produce hydrogen gas
- Blue Litmus turns red
- react with carbonates to produce CO2 gas
- Conduct electric current
- Neutralize bases to produce water and a “salt”(compound)
Bases
- pH greater than 7
- taste bitter
- no reaction with active metals
- feel slippery
- red litmus turns blue
- no reaction with carbonates
- conduct electric current
- neutralize acids to water and a “salt”(ionic compound)
Arrhenius Theory
-theory published to explain the nature of acids and bases
Acid- any substance that dissociates or ionizes in water to produce H+ ions ex. an acid must contain H+ ions
Ex. HCl(aq)-> H+ (aq)+ Cl- ( aq)
Base-any substance that dissociates in water to produce OH- ions. ex. a base must contain OH-
NaOH-> Na+ (aq)+ OH-(aq)
What are the limitations of the Arrhenius Theory
- H+ cannot exist as an ion in water.The positive H+ ions are attracted to the polar water molecules forming Hydronium ions or H3O+ ( aq)
H+(aq) + H2O(l) -> H3O+(aq) - CO2 dissolves in water to produce an acid
NH3 dissolves in water to produce a base
Niether of these observations can be explained by the Arrhenius Theory - Some of the acid-base reactions can occur in solvents other than water.Arrhenius water can explain only aqueous acids or bases
- Arrhenius theory is not able to predict whether certain species are acids or bases
ex. H2PO4- , HCO3
- Modified Arrhenius Theory
(to be used when Arrhenius is inadequate)
Acid-any substance that reacts with water to produce H3O+ ions
Ex. HCl (g) + H2O (l)->H3O+ (aq) + Cl-
Base- any substance that reacts with water to produce OH- ions
EX/. NH3(aq) +H2O (l) –> NH4+(aq) + OH-(aq)
- Bronsted-Lowry Theory
Acid- any substance from which a proton (H+) may be removed
ie. an acid is a substance that loses a proton (H+)
Base- any substance that can remove a proton (H+) from an acid
ie. a base is a substance that gains proton (H+)
In BLT, an acid-base reaction requires the transfer of a proton (H+) from an acid to a base
Eg. HCN (aq) + NH3 (aq)–> CN- (aq) + NH4(aq)
NH3 =base
CN- = conjugate base
NH4= conjugate acid
What is a conjugate acid-base pair ?
BLT theory has conjugate acid-base pair
- Two particles( molecules or ion) that differ by one proton are called a conjugate acid-base pair.
- The conjugate base forms when an acid loses its proton
- The Conjugate acid forms when a base gains a proton (H+)
Amphoteric substance
can be either an acid or a base. Usually these are negative ions that contain at least one hydrogen atom
Strong Acid
A strong acid is an acid that ionizes or dissociates 100% in water
Ex. HCl(aq)—> H+ (aq) + Cl- (aq)
OR
Strong acids react 100% with water
HCl (aq) + H20 (l)—-> H3O+ (aq) + Cl- (aq)
The equilibrium symbol is not used for strong acids because there is no reverse reaction.
Weak Acid
is a base that reacts less than 100% in water to produce OH- ion
ex. S2(aq)- + H2O(l) –> HS- (aq) + OH-(aq)
List three Arrhenius acids that CANNOT be Arrhenius acids
CO2 , HNO3 , H2O
List two Modified Arrhenius bases that cannot be Arrhenius bases
NH3 , HCO 3-
write the formula of three amphoteric compounds
H2O , HSO4 , HCO3
