Inorganic QA (identify from test results) Flashcards
Upon addition of NaOH(aq), no ppt formed. What could it be?
K⁺, Na⁺, Ba²⁺
Effervescence observed:
- NH3 upon heating: NH4⁺
- H2: Zn or Al in water
What is the equation for NH4⁺ upon addition of NaOH(aq)?
NH4⁺ (aq) + OH⁻ (aq) → NH3 (g)+ H2O (l)
What is the equation of Al in water upon addition of NaOH(aq)?
2Al (s) + 2OH⁻ (aq) + 6H2O (l)→ 3H2 (g)+ 2[Al(OH)4]⁻ (aq)
What is the equation of Zn in water upon addition of NaOH(aq)?
Zn (s) + 2OH⁻ (aq) + 2H2O (l) → [Zn(OH)₄]²⁻ (aq) + H2 (g)
Upon addition of NaOH(aq), white ppt. formed. What could it be?
- Ppt. soluble in excess NaOH to form colourless solution: Al³⁺, Zn²⁺
- Ppt. insoluble in excess NaOH: Ca²⁺, Mg²⁺
What is the equation of Al³⁺ upon addition of NaOH(aq)?
Al³⁺ (aq) + 3OH⁻ (aq) → Al(OH)₃ (s)
Al(OH)₃ (s) + OH⁻ (aq) → [Al(OH)₄]⁻ (aq)
What is the equation of Zn²⁺ upon addition of NaOH(aq)?
Zn²⁺ (aq) + 2OH⁻ (aq) → Zn(OH)₂ (s)
Zn(OH)₂ (s) + 2OH⁻ (aq) → [Zn(OH)₄]²⁻ (aq)
What is the equation of Ca²⁺ upon addition of NaOH(aq)?
Ca²⁺ (aq) + 2OH⁻ (aq) → Ca(OH)₂ (s)
What is the equation of Mg²⁺ upon addition of NaOH(aq)?
Mg²⁺ (aq) + 2OH⁻ (aq) → Mg(OH)₂ (s)
Upon addition of NaOH(aq), cream ppt. formed. What could it be?
Ppt. insoluble in excess NaOH (aq), ppt. turned brown on standing in air: Mn²⁺
What is the equation of Mn²⁺ upon addition of NaOH(aq)?
Mn²⁺ (aq) + 2OH⁻ (aq) → Mn(OH)₂ (s)
4Mn(OH)₂ (s) + O₂ (g) +2H2O (l) → 4Mn(OH)₃ (s)
{oxidation}
Upon addition of NaOH(aq), grey-green ppt. formed. What could it be?
Ppt. soluble in excess NaOH(aq) to form a dark green solution: Cr³⁺
What is the equation of Cr³⁺ upon addition of NaOH(aq)?
Cr³⁺ (aq) + 3OH⁻ (aq) → Cr(OH)₃ (s)
Cr(OH)₃ (s) + 3OH⁻ (aq) → [Cr(OH)₆]³⁻ (aq)
Upon addition of NaOH(aq), green ppt. formed. What could it be?
Ppt. insoluble in excess NaOH(aq), ppt. turned brown on standing in air: Fe²⁺
What is the equation of Fe²⁺ upon addition of NaOH(aq)?
Fe²⁺ (aq) + 2OH⁻ (aq) → Fe(OH)₂ (s)
4Fe(OH)₂ (s) + O₂ (g) +2H2O (l) → 4Fe(OH)₃ (s)
{oxidation}
Upon addition of NaOH(aq), red-brown ppt. formed. What could it be?
Ppt. insoluble in excess: Fe³⁺
What is the equation of Fe³⁺ upon addition of NaOH(aq)?
Fe³⁺ (aq) + 3OH⁻ (aq) → Fe(OH)₃ (s)
Upon addition of NaOH(aq), pale blue ppt. formed. What could it be?
Ppt. insoluble in excess, ppt. turned black upon boiling: Cu²⁺
Upon addition of NH₃(aq), no ppt. formed. What could it be?
Ba²⁺, Ca²⁺ , NH4⁺
Upon addition of NH₃(aq), white ppt. formed. What could it be?
- Soluble in excess to give a colourless solution: Zn²⁺
- Insoluble in excess: Al³⁺, Mg²⁺
What is the equation of Zn²⁺ upon addition of NH₃(aq)?
NH₃(aq) + H2O (l) ⇌ NH4⁺ (aq) + OH⁻ (aq)
Zn²⁺ (aq) + 2OH⁻ (aq) → Zn(OH)₂ (s)
Zn(OH)₂ (s) + 4NH₃ (aq) → [Zn(NH₃)₄]²⁺ (aq) + 2OH⁻ (aq)
What is the equation of Al³⁺ upon addition of NH₃(aq)?
NH₃(aq) + H2O (l) ⇌ NH4⁺ (aq) + OH⁻ (aq)
Al³⁺ (aq) + 3OH⁻ (aq) → Al(OH)₃ (s)
What is the equation of Mg²⁺ upon addition of NH₃(aq)?
NH₃(aq) + H2O (l) ⇌ NH4⁺ (aq) + OH⁻ (aq)
Mg²⁺ (aq) + 2OH⁻ (aq) → Mg(OH)₂ (s)
Upon addition of NH₃(aq), off-white ppt. formed. What could it be?
ppt. insoluble in excess NH3(aq), ppt. turned brown on standing in air: Mn²⁺
What is the equation of Mn²⁺ upon addition of NH₃(aq)?
NH₃(aq) + H2O (l) ⇌ NH4⁺ (aq) + OH⁻ (aq)
Mn²⁺ (aq) + 2OH⁻ (aq) → Mn(OH)₂ (s)
4Mn(OH)₂ (s) + O₂ (g) +2H2O (l) → 4Mn(OH)₃ (s)
{oxidation}
Upon addition of NH₃(aq), grey-green ppt. formed. What could it be?
Ppt. insoluble in excess NH3: Cr³⁺
What is the equation of Cr³⁺ upon addition of NH₃(aq)?
NH₃(aq) + H2O (l) ⇌ NH4⁺ (aq) + OH⁻ (aq)
Cr³⁺ (aq) + 3OH⁻ (aq) → Cr(OH)₃ (s)
Upon addition of NH₃(aq), green ppt. formed. What could it be?
ppt. insoluble in excess NH3(aq), ppt. turned brown on standing in air: Fe²⁺
What is the equation of Fe²⁺ upon addition of NH₃(aq)?
NH₃(aq) + H2O (l) ⇌ NH4⁺ (aq) + OH⁻ (aq)
Fe²⁺ (aq) + 2OH⁻ (aq) → Fe(OH)₂ (s)
4Fe(OH)₂ (s) + O₂ (g) +2H2O (l) → 4Fe(OH)₃ (s)
{oxidation}
Upon addition of NH₃(aq), red-brown ppt. formed. What could it be?
ppt. insoluble in excess NH3(aq): Fe³⁺
What is the equation of Fe³⁺ upon addition of NH₃(aq)?
NH₃(aq) + H2O (l) ⇌ NH4⁺ (aq) + OH⁻ (aq)
Fe³⁺ (aq) + 3OH⁻ (aq) → Fe(OH)₃ (s)
Upon addition of NH₃(aq), blue ppt. formed. What could it be?
ppt. soluble in excess to form a dark blue solution: Cu²⁺
What is the equation of Cu²⁺ upon addition of NH₃(aq)?
NH₃(aq) + H2O (l) ⇌ NH4⁺ (aq) + OH⁻ (aq)
Cu²⁺ (aq) + 2OH⁻ (aq) → Cu(OH)₂ (s)
Cu(OH)₂ (s) + 2H2O (l) + 4NH3 (aq) → [Cu(NH3)₄(H2O)₂]²⁺ (aq) + 2OH⁻ (aq)
Why is there no ppt. produced upon adding NH3 in Ca²⁺ solution but white ppt. produced upon adding NaOH?
NH₃ is a relatively weak base with lower [OH⁻] compared than NaOH, it does not precipitate hydroxides of relatively high solubility product
Upon addition of Na₂CO₃ (aq), no ppt. formed. What could it be?
Upon warming, effervescence observed. Colourless and pungent gas turns moist red litmus paper blue, NH3(g) evolved: NH₄⁺
What is the equation of Cu²⁺ upon addition of NaOH(aq)?
Cu²⁺ (aq) + 2OH⁻ (aq) → Cu(OH)₂ (s)
Cu(OH)₂ → CuO (s) + H2O (l){decomposition}
What is the equation of NH₄⁺ upon addition of Na₂CO₃ (aq)?
CO₃²⁻ (aq) + H2O (l) ⇌ HCO3⁻ (aq) + OH⁻ (aq)
NH4⁺ (aq) + OH⁻ (aq) → NH3 (g) + H2O (l)
Upon addition of Na₂CO₃ (aq), white ppt. formed. What could it be?
Ppt. insoluble in excess: Ba²⁺, Ca²⁺, Mg²⁺, Zn²⁺
Effervescence observed, white ppt. formed with a colourless, odourless gas that gave white ppt. with limewater, CO2 evolved: Al³⁺
What is the equation of Al³⁺ upon addition of Na₂CO₃ (aq)?
Hydrolysis occurs due to high charge density:
[Al(H₂O)₆]³⁺ (aq) ⇌ [Al(H₂O)₅OH]²⁺ (aq) + H⁺ (aq)
CO₃²⁻ (aq) + 2H⁺ (aq) → CO₂ (g) + H₂O (l)
Removal of H⁺ shifts the position of equilibrium of hydrolysis to the right
2[Al(H₂O)₆]³⁺ (aq) + 2CO₃²⁻ (aq) → 2[Al(H₂O)₃(OH)₃] (s) + 3CO₂ (g) + 3H₂O (l)
Upon addition of Na₂CO₃ (aq), off-white ppt. formed. What could it be?
Ppt. turned brown on heating: Mn²⁺
What is the equation of Mn²⁺ upon addition of Na₂CO₃ (aq)?
Mn²⁺ (aq) + CO₃²⁻ (aq) → MnCO₃ (s)
2MnCO₃ (s) + O₂ (g) → 2MnO₂ (s) + 2CO₂ (g)
{oxidation}
What is the equation of Ba²⁺ upon addition of Na₂CO₃ (aq)?
Ba²⁺ (aq) + CO₃²⁻ (aq) → BaCO₃ (s)
What is the equation of Ca²⁺ upon addition of Na₂CO₃ (aq)?
Ca²⁺ (aq) + CO₃²⁻ (aq) → CaCO₃ (s)