Chem Mod 8 - Cations/Anions Flame Test
Sure! Below are flashcard-style notes for your HSC Chemistry Module 8 Precipitation Reactions:
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### Cations Flashcards
Lead (II)
- HCl: White precipitate
- NaOH: White precipitate (dissolves in excess NaOH)
- Confirmatory test: Bright yellow lead iodide
- Differentiate: Add NaOH – white ppt dissolves in excess (unlike silver)
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Silver (Ag⁺)
- HCl: White precipitate
- NaOH: Brown precipitate
- Confirmatory test: Silver chloride turns black under sunlight
- Differentiate: Add NaOH – brown ppt that doesn’t dissolve (unlike lead)
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Barium (Ba²⁺)
- HCl: No precipitate
- Na₂SO₄: White precipitate
- Flame test: Green (apple green)
- Differentiate: Add fluoride – no precipitate (unlike calcium)
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Calcium (Ca²⁺)
- HCl: No precipitate
- Na₂SO₄: White precipitate
- Flame test: Brick red
- Differentiate: Add fluoride – white precipitate forms (unlike barium)
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Copper (Cu²⁺)
- HCl: No precipitate
- NaOH: Blue precipitate
- Confirmatory test: Copper compounds are always blue
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Iron (III) (Fe³⁺)
- HCl: No precipitate
- NaOH: Brown precipitate
- Confirmatory test: Forms deep red solution with thiocyanate (SCN⁻)
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Iron (II) (Fe²⁺)
- HCl: No precipitate
- NaOH: Pale green precipitate
- Confirmatory test: Decolorizes acidified potassium permanganate (oxidizing)
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Aluminium (Al³⁺)
- HCl: No precipitate
- NaOH: White precipitate (dissolves in excess NaOH)
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Magnesium (Mg²⁺)
- HCl: No precipitate
- NaOH: White precipitate
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### Anions Flashcards
Chloride (Cl⁻)
- HNO₃: No precipitate
- Ba(NO₃)₂: No precipitate
- AgNO₃: White precipitate
- Confirmatory test: Precipitate dissolves in dilute NH₃ and turns black under sunlight
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Bromide (Br⁻)
- HNO₃: No precipitate
- Ba(NO₃)₂: No precipitate
- AgNO₃: Pale yellow precipitate
- Confirmatory test: Precipitate dissolves in concentrated NH₃
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Iodide (I⁻)
- HNO₃: No precipitate
- Ba(NO₃)₂: No precipitate
- AgNO₃: Yellow precipitate
- Confirmatory test: Lead iodide is bright yellow, and the AgNO₃ precipitate doesn’t dissolve in NH₃
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Hydroxide (OH⁻)
- HNO₃: No precipitate
- Ba(NO₃)₂: No precipitate
- AgNO₃: Brown precipitate
- Confirmatory test: Green/cyan precipitate with iron (II), turns red as it oxidizes to iron (III)
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Carbonate (CO₃²⁻)
- HNO₃: Bubbles (CO₂ release)
- Confirmatory test: Add HCl, observe effervescence
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Sulfate (SO₄²⁻)
- HNO₃: No precipitate
- Ba(NO₃)₂: White precipitate
- Differentiate: Precipitates in acidic conditions (unlike phosphate)
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Phosphate (PO₄³⁻)
- HNO₃: No precipitate
- Ba(NO₃)₂: White precipitate
- Confirmatory test: Precipitates with NaOH and Ba(NO₃)₂ (unlike sulfate)
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Acetate (CH₃COO⁻)
- HNO₃: No precipitate
- Ba(NO₃)₂: No precipitate
- AgNO₃: No precipitate
- Confirmatory test: Red precipitate with iron (III) chloride
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### Differentiation Tests
Barium vs Calcium
- Add fluoride:
- Calcium: White precipitate
- Barium: No precipitate
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Lead vs Silver
- Add NaOH:
- Lead: White precipitate (dissolves in excess)
- Silver: Brown precipitate (doesn’t dissolve)
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Phosphate vs Sulfate
- Acidic conditions:
- Sulfate: Precipitates
- Phosphate: Does not
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These flashcards summarise confirmatory tests and differentiate reactions for common cations and anions studied in HSC Chemistry.
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