precipitate anorganica
TRANSCRIPT
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PRECIPITATE
HIDROXIZI
Reactivi: NaOH, KOH, NH4OH
Ag+: AgOH – pp alb murdar (instabil) 2AgOH → Ag2O + H2O
pp brun (solubil in exces de NH3)
2AgNO3 + 2NaOH → Ag2O + 2NaNO3 + H2O
Ag2O + 4NH3 + H2O → 2[Ag(NH3)2](OH) – solutie incolora
Al3+: Al(OH)3 – pp alb gelatinos (solubil in exces de HO-)
Al(NO3)3 + 3NaOH → Al(OH)3 + 3NaNO3
Al(OH)3 + NaOH → Na[Al(OH)4] – solutie incolora
Be2+: Be(OH)2 – pp alb gelatinos (solubil in exces de HO-)
BeCl2 + 2NaOH → Be(OH)2 + 2NaCl
Be(OH)2 + 2NaOH → Na2[Be(OH)4] – solutie incolora
Bi3+: • cu NaOH sau KOH: Bi(OH)3 – pp alb gelatinos
• cu NH4OH: Bi(OH)2NO3 – pp alb → Bi(OH)3 (exces de reactiv)
Ca2+: Ca(OH)2 – pp alb, partial solubil in apa (insolubil in exces NH3 sau HO-)
CaCl2 + 2NaOH → Ca(OH)2 + 2NaCl
Cd2+: Cd(OH)2 – pp alb gelatinos (solubil in exces de NH3)
CdCl2 + 2NaOH → Cd(OH)2 + 2NaCl
Cd(OH)2 + 4NH3 → [Cd(NH3)4](OH)2 – solutie incolora (repp prin diluare si fierbere)
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Co2+: • cu NaOH sau KOH: Co(OH)Cl → Co(OH)2 → Co(OH)2 ∙ Co(OH)3 → Co(OH)3 (solubil in NH3)
pp albastru → roz → roz murdar → brun
SUB ACTIUNEA O2 DIN AER
Co(OH)2 + 6NH3 → [Co(NH3)6](OH)2 – solutie galben murdar
Co(OH)2 + 2NaOH → Na2[Co(OH)4]
• cu NH4OH: Co(OH)Cl sau (CoOH)2SO4 – pp albastre (solubile in NH3)
Cr3+: Cr(OH)3 – pp verde-cenusiu gelatinos (solubil in HO- si partial solubil in NH3 → [Cr(NH3)6]3+ -
violet-rosiat)
CrCl3 +3NaOH → Cr(OH)3 + 3NaCl
Cr(OH)3 + NaOH → Na[Cr(OH)4] – solutie verde f inchis (prin diluare sau fierbere repp
total)
[Cr(OH)4]-: • cu Na+ sau K+ - solubil
• cu ioni divalenti (Mg2+, Zn2+, Mn2+, Fe2+ etc.) – comp greu solubili M[Cr(OH)4]2
Cu+: CuOH – pp galben (insolubil in HO-)
Cu2+: • cu NaOH sau KOH: Cu(OH)2 – pp albastru-verzui gelatinos (solubil in NH3)
CuCl2 + 2NaOH → Cu(OH)2 + 2NaCl
Cu(OH)2 + 4NH3 → [Cu(NH3)4](OH)2 – solutie albastru-indigo (reactiv Schweitzer)
• cu NH4OH, (NH4)2CO3, Na2CO3, K2CO3: CuSO4∙Cu(OH)2 – pp verde purverulent
Fe2+: • cu NaOH sau KOH: Fe(OH)2 → Fe(OH)2∙2Fe(OH)3 → Fe(OH)3
pp alb → verde inchis → rosu brun
SUB ACTIUNEA O2 DIN AER
• cu NH4OH: Fe(OH)2 – pp incompleta
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Fe3+: Fe(OH)3 – pp rosu-brun (insolubil in exces de HO- sau NH3)
FeCl3 + 3NaOH → Fe(OH)3 + 3NaCl
Hg22+: • cu NaOH sau KOH: Hg2(OH)2 – pp alb (instabil) Hg2(OH)2 → Hg2O + H2O
pp negru (la cald se transf in HgO + Hg)
• cu NH4OH: 2Hg2(NO3)2 + 4NH3 + H2O → NH2Hg2ONO3 + 2Hg + 3NH4NO3
pp alb pp negru
Hg2Cl2 + 2NH3 → NH2HgCl + Hg + NH4Cl
pp alb pp alb pp negru
Hg2+: • cu NaOH sau KOH: Hg(OH)2 – instabil Hg(OH)2 → Hg2O + H2O
pp galben
HgCl2 + 2NaOH → Hg2O + NaCl + H2O
• cu NH4OH: 2Hg(NO3)2 + 4NH3 + H2O → NH2Hg2ONO3 + 3NH4NO3
HgCl2 + NH3 → HgClNH2 + NH4Cl
Mg2+: • cu NaOH sau KOH: Mg(OH)2 – pp alb gelatinos
• cu NH4OH: Mg(OH)2 – pp incompleta
Mn2+: • cu NaOH sau KOH: Mn(OH)2 → MnO∙MnO2 + Mn(OH)3
pp alb → brun
SUB ACTIUNEA O2 DIN AER
• cu NH4OH: Mn(OH)2 – pp incompleta
Ni2+: • cu NaOH sau KOH: Ni(OH)2 – pp verde deschis amorf (insolubil in exces de HO-, dar
solubil in NH3)
NiCl2 + 2NaOH → Ni(OH)2 + 2NaCl
Ni(OH)2 + 6NH3 → [Ni(NH3)6](OH)2 – solutie violet-albastruie
• cu NH4OH: NiOHCl sau (NiOH)2SO4 (solubile in NH3 → [Ni(NH3)6]2+ )
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Pb2+: Pb(OH)2 –pp alb purverulent (solubil in exces de HO -, dar insolubil in NH3)
Pb(NO3)2 + 2NaOH → Pb(OH)2 + 2NaNO3
Pb(OH)2 + 2NaOH → Na2[Pb(OH)4] – solutie incolora
Sb3+: Sb(OH)3 – pp alb (usor solubil in exces de HO-, dar insolubil in NH3)
Sb(OH)3 + NaOH → Na[Sb(OH)4] – solutie incolora
Sn2+: Sn(OH)2 – pp alb gelatinos (solubil in HO-)
Sn(OH)2 + 2NaOH → Na2[Sn(OH)4] – solutie incolora
Sn4+: Sn(OH)4 – pp alb voluminous (solubil in HO-)
Sn(OH)4 + 2NaOH → Na2[Sn(OH)6]
Zn2+: Zn(OH)2 – pp alb gelatinos (solubil in exces de HO- sau NH3)
ZnCl2 + 2NaOH → Zn(OH)2 + 2NaCl
Zn(OH)2 + 2NaOH → Na2[Zn(OH)4] – solutie incolora
Zn(OH)2 + 4NH3 → [Zn(NH3)4](OH)2 - solutie incolora
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CARBONATI
Reactivi: Na2CO3 , K2CO3 , (NH4)2CO3
Ag+: Ag2CO3 – pp alb galbui
• cu Na2CO3 sau K2CO3: se desc usor la cald: Ag2CO3 → Ag2O + CO2
• cu (NH4)2CO3: solubil in exces de reactiv
hid
Al3+: Al2(CO3)3 -----→ Al(OH)3 (cu Na2CO3 sau K2CO3)
2AlCl3 + 3Na2CO3 → Al2(CO3)3 + 6NaCl
Ba2+: BaCO3 – pp alb, cristalin (pp cu (NH4)2CO3 , Na2CO3 la cald, K2CO3)
t˚C
BaCl2 + Na2CO3 -----→ BaCO3 + 2NaCl
Be2+
: BeCO3 ∙ Be(OH)2 – pp alb, solubil in exces de reactiv (Na2CO3, K2CO3, (NH4)2CO3)
Ca2+: CaCO3 – pp alb cristalin
Ca(OH)2 + CO2 → CaCO3 + H2O
CaCl2 + Na2CO3 → CaCO3 + 2NaCl
Cd2+: CdCO3 ∙ nCd(OH)2 – pp alb
• cu Na2CO3 sau K2CO3: insolubil in exces de reactiv
• cu (NH4)2CO3: solubil in exces de reactiv → [Cd(NH3)4]2+
Co2+: CoCO3 ∙ Co(OH)2 – pp albastru (solubil in NH3)
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hid
Cr3+: Cr2(CO3)3 -----→ Cr(OH)3
Cu2+: CuCO3 – pp verde
CuCl2 + Na2CO3 → CuCO3 + 2NaCl
Fe2+: FeCO3 → Fe(OH)3 (cu Na2CO3 sau K2CO3)
pp alb → rosu brun
SUB ACTIUNEA O2 DIN AER
Fe3+: Fe(OH)CO3 – pp brun (cu Na2CO3 sau K2CO3)
Hg22+: Hg2(CO3)2 – pp galben
Hg2(NO3)2 + 2Na2CO3 → Hg2(CO3)2 + 4NaNO3
la cald: Hg2(NO3)2 + Na2CO3 → HgO + CO2 + Hg + 2NaNO3
Hg2+: • daca se foloseste solutie de Hg(NO3)2: HgCO3 ∙ 3HgO – pp rosu brun
• daca se foloseste solutie de HgCl2: HgCl2 ∙ 2HgO
Li+: Li2CO3 – pp alb (pp la cald si in mediu amoniacal)
2LiCl + (NH4)2CO3 → Li2CO3 + 2NH4Cl
Mg2+: • cu Na2CO3 sau K2CO3: nMgCO3 ∙ mMg(OH)2 ∙ xH2O – pp alb
• cu (NH4)2CO3: 3MgCO3 ∙ Mg(OH)2 – pp incompleta
Mn2+
: MnCO3 – pp alb, care se oxideaza partial in aer → H2MnO3 – pp brun inchis
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Ni2+: NiCO3 – pp verde gelatinos (solubil in NH3)
Pb2+: PbCO3 ∙ Pb(OH)2 –pp alb (cu Na2CO3 sau K2CO3)
hid
Sb3+: Sb2(CO3)3 -----→ Sb(OH)3 – pp alb
Sn2+: SnCO3 – pp alb
Sr2+: SrCO3: - pp alb
Zn2+: ZnCO3 ∙ 3Zn(OH)2 – pp alb
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SULFATI
Reactivi: Na2SO4 , K2SO4 , CaSO4 , (NH4)2SO4 , H2SO4
Ag+: Ag2SO4 – pp alb (pp cu H2SO4 diluat si Na2SO4 si numai cu sol conc in Ag+)
2AgNO3 + Na2SO4 → Ag2SO4 + 2NaNO3
2AgNO3 + H2SO4 → Ag2SO4 + 2HNO3
Ba2+: BaSO4 – pp alb micro-cristalin (pp cu H2SO4 diluat, (NH4)2SO4 , CaSO4)
CaSO4 + BaCl2 → BaSO4 + CaCl2
H2SO4 + BaCl2 → BaSO4 + 2HCl
(NH4)2SO4 + BaCl2 → BaSO4 + 2NH4Cl
Be2+: BeK2(SO
4)
2 – pp alb cristalin (pp cu sol de K
2SO
4 )
Be2+ + K2SO4 → BeK2(SO4)2
Ca2+: CaSO4 – pp alb, partial solubil (pp cu H2SO4 diluat, (NH4)2SO4)
H2SO4 + CaCl2 → CaSO4 + 2HCl
(NH4)2SO4 + CaCl2 → CaSO4 + 2NH4Cl
Cr3+: KCr(SO4)2 ∙ 12H2O / CsCr(SO4)2 ∙ 12H2O – cristale triunghiulare (pp cu K2SO4 / Cs2SO4)
Pb2+: PbSO4 –pp alb (pp cu H2SO4 diluat)
Pb(NO3)2 + H2SO4 → PbSO4 + 2HNO3
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Sr2+: SrSO4 – pp alb (pp cu H2SO4 diluat, (NH4)2SO4 , CaSO4)
CaSO4 + SrCl2 → SrSO4 + CaCl2
H2SO4 + SrCl2 → SrSO4 + 2HCl
(NH4)2SO4 + SrCl2 → SrSO4 + 2NH4Cl
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SULFITI
Reactivi: Na2SO3
Ag+: Ag2SO3 – pp alb (solubil in exces de SO32-)
2AgNO3 + Na2SO3 → Ag2SO3 + 2NaNO3
Ag2SO3 + 3Na2SO3 → 2Na3[Ag(SO3)2] – solutie incolora
Ba2+: BaSO3 – pp alb
BaCl2 + Na
2SO
3→ BaSO
3+ 2NaCl
Ca2+: CaSO3 – pp alb
CaCl2 + Na2SO3 → CaSO3 + 2NaCl
Pb2+: PbSO3 – pp alb
PbCl2 + Na2SO3 → PbSO3 + 2NaCl
Sn2+: SnSO3 – pp alb
SnCl2 + Na2SO3 → SnSO3 + 2NaCl
Sr2+: SrSO3 – pp alb
SrCl2 + Na2SO3 → SrSO3 + 2NaCl
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TIOSULFATI
Reactivi: Na2S2O3
Ag+: Ag2S2O3 – pp alb → galben → rosu → brun → negru (solubil in exces de S2O32-)
datorita descompunerii pana la sulfura
2AgNO3 + Na2S2O3 → Ag2S2O3 + 2NaNO3
Ag2S2O3 + 3Na2S2O3 → 2Na3[Ag(S2O3)2] – solutie incolora
hid
Al3+: Al2(S
2O
3)
3 -----→ Al(OH)
3 – pp alb gelatinos
Ba2+: BaS2O3 – pp alb cristalin
BaCl2 + Na2S2O3 → BaS2O3 + 2NaCl
hid
Bi3+: Bi2(S2O3)3 -----→ Bi2S3 – pp brun inchis
pp alb
Ca2+: CaS2O3 – pp albastru
CaCl2 + Na2S2O3 → CaS2O3 + 2NaCl
Co2+: CoS2O3 – pp albastru-azuriu, cristalin
CoCl2 + Na2S2O3 → CoS2O3 + 2NaCl
hid
Cr3+: Cr2(S2O3)3 -----→ Cr(OH)3 – pp verde-cenusiu gelatinos (impurificat cu S)
hid Fe3+: Fe2(S2O3)3 -----→ Fe(OH)3 – pp rosu-brun
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Pb2+: PbS2O3 – pp alb (solubil in exces de reactiv)
Pb(NO3)2 + Na2S2O3 → PbS2O3 + 2NaNO3
Sr2+: SrS2O3 – pp alb
SrCl2 + Na2S2O3 → SrS2O3 + 2NaCl
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FOSFATI
Reactiv: Na2HPO4
Ag+: Ag3PO4 – pp galben (pp cu Na2HPO4 , solubil in exces de NH3)
3AgNO3 + Na2HPO4 → Ag3PO4 + 2NaNO3 + H+
Al3+: AlPO4 – pp alb voluminos
Al(NO3)3 + Na2HPO4 → AlPO4 + NaNO3 + H+
Ba2+: BaHPO4 – pp alb cu fulgi
• in prezenta de NH3: Ba3(PO4) – pp alb
Be2+: BeNH4PO4 – pp alb cristalin (cu (NH4)2HPO4)
Be2+ + (NH4)2HPO4 → BeNH4PO4
Bi3+: BiPO4 – pp alb cristalin
Bi(NO3)3 + Na2HPO4 → BiPO4 + NaNO3 + H+
Ca2+: CaHPO4 – pp alb cu fulgi
• in prezenta de NH3: Ca3(PO4) – pp alb
Cd2+: pp in mediu de NH3
Cd(NO3)2 + Na2HPO4 + NH3 → CdNH4PO4 + NaNO3
pp alb
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Co2+: Co3(PO4)2 – pp violet
CoCl2 + Na2HPO4 → Co3(PO4)2 + NaCl + H+
Cr3+: CrPO4 – pp verde
Cr(NO3)3 + Na2HPO4 → CrPO4 + NaNO3 + H+
Fe2+: Fe2+ + Na2HPO4 → FeHPO4 ∙ Fe3(PO4)2
pp alb-verzui
Fe
3+
: FePO4 – pp galben-verziu
FeCl3 + Na2HPO4 → FePO4 + NaNO3 + H+
Hg2+: Hg3(PO4)2 – pp alb
Hg(NO3)2 + Na2HPO4 → Hg3(PO4)2 + NaNO3 + H+
Li+: Li3PO4 – pp alb cristalin (in mediu alcalin si la cald)
Li+ + Na2HPO4 → Li3PO4 + Na+ + H+
Mg2+: pp in mediu de NH3
Mg(NO3)2 + Na2HPO4 + NH3 → MgNH4PO4 + NaNO3
pp alb
Mn2+: Mn3(PO4)2 – pp alb
Mn(NO3)2 + Na2HPO4 → Mn3(PO4)2 + NaNO3 + H+
Ni2+: Ni3(PO4)2 – pp verde
Ni(NO3)2 + Na2HPO4 → Ni3(PO4)2 + NaNO3 + H+
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Pb2+: Pb3(PO4)2 – pp alb
Pb(NO3)2 + Na2HPO4 → Pb3(PO4)2 + NaNO3 + H+
Sn2+: Sn3(PO4)2 – pp alb (pp cu H3PO4 si Na2HPO4)
Sn(NO3)2 + Na2HPO4 → Sn3(PO4)2 + NaNO3 + H+
Sn(NO3)2 + H3PO4 → Sn3(PO4)2 + HNO3
Sr2+: SrHPO4 – pp alb
• in prezenta de NH3: Ca3(PO4) – pp alb
Zn2+: Zn3(PO4)2 – pp alb
Zn(NO3)2 + Na2HPO4 → Zn3(PO4)2 + NaNO3 + H+
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CROMATI si BICROMATI
Reactivi: K2CrO4 , K2Cr2O7
Ag+: • cu K2CrO4: Ag2CrO4 – pp rosu-brun cristalin
• cu K2Cr2O7: Ag2CrO4 – pp rosu-brun (disproportioneaza → Ag2CrO4 + CrO3)
Ba2+: BaCrO4 – pp galben cristalin
Bi3+: (BiO)2Cr2O7 – pp galben-portocaliu
Ca2+: CaCrO4 – cristale galbene sub forma de bastonase (pp cu K2CrO4 doar la conc mari de Ca2+)
Hg22+: Hg2CrO4 – pp rosu voluminos (la rece), granulos (la cald)
Hg2+: HgCrO4 – pp galben (pp cu K2CrO4 si cu K2Cr2O7 numai folosind solutii de azotat)
Mn2+: MnCrO4 – pp brun (pp doar cu K2CrO4)
Ni2+: NiCrO4 ∙ Ni(OH)2 – pp galben (pp doar cu K2CrO4)
Pb2+: PbCrO4 – pp galben stralucitor
Sr2+: SrCrO4 – prisme galbene, partial solubile in apa (pp cu K2CrO4 doar la conc mari de Sr2+ )
Zn2+: ZnCrO4 – pp galben (pp doar cu K2CrO4)
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OXALATI
Reactivi: (NH4)2C2O4
Ag+: Ag2C2O4 – pp alb
Ba2+: BaC2O4 – pp alb cristalin (solubil in exces mare de reactiv)
BaCl2 + (NH4)2C2O4 → BaC2O4 + 2NH4Cl
Ca2+: CaC2O
4 – pp alb cristalin
Cd2+: CdC2O4 – pp greu solubil cristalin (prisme incolore sau paralelograme mici)
Cu2+: CuC2O4 – pp albastru-deschis
Fe2+: FeC2O4 – pp relativ greu solubil
Mg2+: MgC2O4 – pp alb cristalin
Mn2+: MnC2O4 – pp roz-pal cristalin (sub forma de prisme, x-uri sau baghete)
• in mediu acetic se form [Mn(C2O4)2]
-
- solutie rosie
Sr2+: SrC2O4 – pp alb cristalin
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CIANURI
Reactivi: NaCN, KCN
hid
Bi3+: Bi(CN)3 -----→ Bi(OH)3 – pp brun inchis
Co2+: Co(CN)2 – pp roz (solubil in exces de reactiv)
Co(CN)2 + 4CN- → [Co(CN)6]4-
Cu+
: CuCN – pp alb (insolubil in exces de reactiv)
CuCN + 3KCN → K3[Cu(CN)4]
Cu2+: Cu(CN)2 – pp galben (disproportioneaza usor cu formare de CuCN - pp alb si (CN)2 )
2Cu(CN)2 → 2CuCN + (CN)2
Hg22+: Hg(CN)2 – pp alb + Hg – pp negru
Hg2+: Hg(CN)2 – pp alb (solubil in exces de reactiv)
Hg(CN)2 + CN- → [Hg(CN)4]2-
Mn
2+
: Mn(CN)2 – pp brun
Ni2+: Ni(CN)2 – pp verde galbui
Pb2+: Pb(CN)2 –pp alb
Sn2+: Sn(CN)2 – pp alb
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PERCLORATI
Reactivi: NH4ClO4
Cd2+: [Cd(NH3)4](ClO4)2 – pp alb cristalin
Cd2+ + NH4ClO4 → [Cd(NH3)4](ClO4)2
ACETATI
Reactivi: CH3COONa
Al3+: Al(OH)3 ∙ CH3COO – pp alb amorf
METALE ALCALINE
Li+: Li+ + [Al(OH)4]- → LiAl2(OH)7
pp alb cristalin
Na+: Na[Sb(OH)6] – pp alb
NaUO2(CH3COO)3 – pp galben-verzui cristalin
NaM(UO2)(CH3COO)9 ∙ xH2O – pp galben, galben-verzui, verzi octaedrice
M = Zn2+, Mg2+, Co2+, Ni2+ etc
K+: K2Na[Co(NO2)6] – pp galben cristalin
K3[BI(S2O3)3] – pp galben cristalin
K3[Co(S2O3)3] – pp albastru
Cs+: Cs[BiI4] ∙ CsI – pp galben-portocaliu sub forma de placi hexagonale
Cs[PbI3] – pp verde-galbui cristalin
Cs[Ag2I3] – pp galben cristalin
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SULFURI
Reactivi: Na2S, K2S, (NH4)2S, H2S
Ag+: Ag2S – pp negru
hid
Al3+: Al2S3 -----→ Al(OH)3 – pp alb gelatinos (pp cu (NH4)2S)
hid
Be2+: BeS -----→ Be(OH)2 – pp alb gelatinos (pp cu (NH4)2S)
Bi3+: Be2S3 – pp brun inchis (pp cu H2S)
Co2+: CoS – pp negru (pp cu (NH4)2S)
hid
Cr3+: Cr2S3 -----→ Cr(OH)3 – pp verde-cenusiu gelatinos (pp cu (NH4)2S)
Cu+: se obtine CuS – pp negru (pp cu H2S)
Cu2+: CuS – pp negru (pp cu H2S; insolubil in H2SO4 )
Fe2+: FeS – pp negru (pp cu (NH4)2S )
Fe3+: Fe2S3 – pp negru (pp cu (NH4)2S )
Hg22+: Hg2S → HgS + Hg (pp cu H2S, (NH4)2S)
pp negru
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Hg2+: 2HgS ∙ HgCl2 – pp alb → galben → brun → negru (HgS) (pp cu H2S)
EXCES DE REACTIV
Mg2+: • cu NaS: Mg(OH)2 – pp completa
• cu (NH4)2S: Mg(OH)2 – pp incompleta
Mn2+: MnS – pp roz ca pielea care se imbruneaza prin sedere in aer (pp cu (NH4)2S )
Ni2+: NiS – pp negru (pp cu (NH4)2S )
Pb2+: PbS – pp negru
Sb3+: Sb2S3 – pp rosu – portocaliu voluminos (pp cu H2S)
Sb5+: Sb2S5 – pp rosu – portocaliu voluminos (pp cu H2S)
Sn2+: SnS – pp brun (pp cu H2S)
Sn4+: SnS2 – pp galben (pp cu H2S)
Zn2+: ZnS – pp alb (pp cu H2S, (NH4)2S)
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FLUORURI
Reactivi: NaF, KF, NH4F
Al3+: Al3+ + NaF → AlF3
→ Al[AlF6] compusi albi greu solubili (pp cu NaF)
→ Na3[AlF6]
Ba2+: BaF2 – pp alb
Ca2+: CaF2 – pp alb gelatinos
Fe3+: Na3[FeF6] – pp alb cristalin, greu solubil
Li+: LiF – pp alb gelatinso (pp cu NH4F in exces de NH3)
Mg2+: MgF2 – pp alb
Sr2+: SrF2 – pp alb
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CLORURI
Reactivi: HCl diluat, NaCl, KCl
Ag+: AgCl – pp alb care se innegreste la lumina
• solubil in: NH3: [Ag(NH3)2]+
KCN: [Ag(CN)2]-
KSCN: [Ag(SCN)2]-
HCl conc: [AgCl2]-
Hg22+: Hg2Cl2 – pp alb (solubil in exces de reactiv)
Hg2Cl2 + NH3 → Hg2NH2Cl + Hg
pp alb pp negru
Pb2+: PbCl2 – pp alb cristalin (prisme rombice) solubil la incalzire
PbCl2 + Cl- → [PbCl3]-
→ [PbCl4]2-
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BROMURI
Reactivi: NaBr, KBr
Ag+: AgBr – pp galben deschis
• solubil in: NH3: [Ag(NH3)2]+
KCN: [Ag(CN)2]-
Hg22+: Hg2Br2 – pp galben, greu solubil
Pb2+: PbBr2 – pp alb (solubil in exces de reactiv)
PbBr2 + 2NaBr → Na2[PbBr4]
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IODURI
Reactivi: NaI, KI
Ag+: AgI – pp galben (insolubil in NH3 , dar solubil in CN-; pp cu NaBr sau KBr)
Bi3+: BiI3 – pp negru (pp cu ioduri alcaline, in mediu acid)
Hg22+: Hg2I2 – pp verde galbui (instabil)
Hg2I2 → HgI2 + Hg
pp rosu-caramiziu pp negru
HgI2 + 2I- → [HgI4]2-
Hg2+: HgI2 – pp rosu-caramiziu (pp cu KI, usor solubil in exces de reactiv)
HgI2 + 2I- → [HgI4]2- (reactiv Nessler)
Pb2+: PbI2 – pp galben (solubil in HI conc)
PbI2 + 2HI → H2[PbI4]
Sn2+: SnI2 – pp galben-auriu (pp cu KI 10% si in prez H2SO4 conc)