Gen Chem 2 Exam 3

at pH 7 half rxns for water

H2 red = -0.42

O2 ox = +0.82

• both share ox

G1 metal reactions with O2 gas

Li, (Na) → oxide

Na, (K) → peroxide

K, Rb, Cs → superoxide

metals that form oxides

Li

• Na (when limited oxygen)

metals that form superoxides

K, Rb, Cs

metals that form peroxides

Na

• K (when limited oxygen)

oxygen compound types

oxide = M₂O

• (O^2-)

• just normal O

superoxide = MO2

• (O₂^2-)

• “super” pretty good but not perfect (2 O)

peroxide = M₂O₂

• (O₂^-)

• “perfect” = the largest

oxide

M₂O

superoxide

MO2

peroxide

M₂O₂

how to recall reaction products between oxygen & G1

as go down table, they’re in a row

• aka top oxide (Li- Na when lim), middle peroxide (Na- K lim), bottom superoxide (K, Rb, Cs)

Li exception to G1

• reacts w/ N₂ to give metal nitride

reasoning: high charge-to-size ratio (bc small rad) = forms short bonds = a lot of interactions

density does what down G1

increases

charge-to-size ratio does what down G1

decreases

• think of how Li is exception & has greatest

Be exception to G2

BeO is amphoteric

covalent not ionic

rxns of G2 w/ oxygen

M + O2 → MO

• EXCEPT Ba produces peroxide (Ba + O2 → BaO2)

larger G2 metals reduce H2O to produce H2 (g)

• Ca, Sr, Ba

• ex: Ca + H2O → Ca(OH) + H2

wrote unbalanced coeffs

which G2 metal produces peroxide instead of oxide?

Ba

• heaviest in the group

G2 rxn w/ N2

w/ N2 → metal nitride

• Mg (mega powerful, he’s just that guy, he’s hot enough himself) at all temps, other metals only at high temps

• ex: Sr + N2 → Sr3N2

G2 rxns w/ carbon

M + CO2 → MO + C

G2 oxide + CO2 → carbonate (CO3)

• ex: SrO + CO2 → SrCO3

G2 carbonates decompose w/ heat (so the above but reverse)

• ex: CaCO3 → CaO + CO2