G. Reactivities of Inorganic Compounds Flashcards
(51 cards)
Acid and bases properties
Acid - sour, blue to red litmus, corrode metals to produce hydrogen gas
Base - bitter, red to blue litmus, slippery
Differentiate the three definitions of acid and base
- Arrhenius
→ acid: produces H+ ions (H3O+)
→ base: produces OH- ions - Bronsted-Lowry
→ acid: H+ donor
→ base: H+ acceptor - Lewis
→ acid: electron pair acceptor
→ base: electron pair donor
Differentiate amphoteric and amphiprotic
Amphoteric - can act as base or acid
Amphiprotic - can both donate and accept a proton (Bronsted-Lowry)
NOTE: all amphiprotic substances are amphoteric, but not all amphoteric substances are amphiprotic
Factors that influence acidity
Charge, Atom, Resonance, Dipole Interaction, Orbitals
(CARDIO)
As charge became more ___, acidity increases (↓pH). Explain
As charge became more positive, acidity increases (↓pH)
OH- < H2O < H3O+
→ higher positive charge stabilizes the conjugate base
→ easier to release a proton
Arrange the following in order of increasing acidity. Explain
NH3, H2O, CH4, HF
CH4 < NH3 < H2O < HF
↑ acidity as ↑ EN across a period
→ EN atoms attract electron density more strongly
→ stabilizes the conjugate base
Arrange the following in order of increasing acidity. Explain
HF, HCl, HBr, HI
HF < HCl < HBr < HI
↑ acidity as ↑ size down a group
→ large atoms form weaker X-H bonds
→ easier to release H+ ions
Acidity increases with stability of ____ due to _____
↑ acidity ↑ stability of conjugate base due to resonance
Which is more acidic?
HOOCCH2CH2Br or HOOCCH2Br
HOOCCH2Br
↑ acidity as ↓ distance of EWG (Br)
Acidity increases as ___ EN and ___ EWG
Acidity increases as ↑ EN and ↑ EWG
Arrange the following based on increasing acid strength. Explain
CH3CH3, CH2=CH2, CH≡CH
CH3CH3 < CH2=CH2 < CH≡CH
↑ acidity as ↑ s character
single bond = 25% s
double bond = 33% s
triple bond = 50% s
How does a proton become an acidic proton?
It bears a partial positive charge because of its attachment to an electronegative atom or an electron withdrawing group
Differentiate aqua acid, hydroxoacid, and oxoacid in terms of (1) acidic proton (2) central atom
- Aqua acid [M(H2O)n]^m+
→ Lewis acid + Lewis base (H2O)
→ acidic proton is on the water ligand
→ metal center (d-block, group 2, or low oxidation metals) - Hydroxoacid [M(OH)n]
→ acidic proton is on hydroxyl group w/o a neighboring oxo group
→ central atom is p-block or d-block element - Oxoacid [OpE(OH)q]
→ acidic proton is on hydroxyl group with oxo group attached to same atom
→ nonmetal central atom
→ follows Pauling’s Rule
Pauling’s Rules for pKa values
pKa = 8 - 5p
pKa2 = pKa1 + 5
pKa3 = pKa2 + 5
Oxoacid [OpE(OH)q]
p = no. of oxo group (=O)
q = no. of acidic protons
Acidity of aqua acids (and hydroxoacids) increases with ____ ionic radius of central atom. Explain
↑ acidity ↓ ionic radius of central atom (M)
→ smaller central atom (M), higher charge density, shorter bond distance of M-O
→ M withdraw electrons from O more strongly
→ ↑ polarity of O-H bond in H2O (distance partial positive charge on H and partial negative charge on oxygen increases)
→ more positive acidic proton, easier to release
Acidity of hydroxoacids (and aqua acids) increases with ____ charge of central atom. Explain
↑ acidity ↑ charge of central atom
→ ↑ charge of central atom = more easily it withdraws electron from oxygen
→ ↑ polarity of O-H
→ more positive acidic proton, easier to release
Acidity of oxoacids increases with ____ electronegativity of central atom (E). Explain
↑ acidity ↑ EN of E
→ ↑ EN of E = easier to withdraw electrons from O of an OH group
→ ↑ polarity of O-H
→ more positive acidic proton, easier to release
Acidity of oxoacids increases with ____ no. of oxo groups. Explain
↑ acidity ↑ no. of oxo groups
→ electron withdrawing O weakens the O-H bond
→ ↑ polarity of O-H
→ more positive acidic proton, easier to release
Acidity of oxoacids increases with ____ resonance stabilziation of conjugate base.
↑ acidity ↑ stability of conj. base due to resonance
→ greater number of resonance contributions, more acidic
Nonmetal oxides such as CO2 are ____ in aqueous solution and in the form of ___
acidic
(H2CO3 in aq. sol’n)
Metal oxides such as BaO are ___ in aqueous solution and in the form of ____
basic
Ba(OH)2 in aq. sol’n
Metalloid oxides such as Al2O3 are ___ in aqueous solution and in the form of ___
amphoteric
[Al(OH2)6]3+ and [Al(OH)4]-
Arrange the following metal ions with increasing acid strength. Explain
K+, Na+, Al3+, Fe3+
K+ < Na+ < Al3+ < Fe3+
- K+, Na+ < Al3+, Fe3+
→ ↑ charge of metal ion = ↑ acid strength
→ attract electron pairs more - K+ < Na+
→ ↓ ionic radius = ↑ acid strength - Al3+ < Fe3+
→ Fe3+ has d orbitals
Classify BF3 as acid or base. Explain
BF3 - Lewis acid
→ electron-deficient (incomplete octet)
→ electron acceptor