Questions and Answers
What flame color is observed for sodium ion during a flame test?
What color is transmitted through cobalt blue glass when viewing potassium ion?
Lavender
The equilibrium equation for ammonium ion is NH3(aq) + H2O(l) ⇌ ________.
NH4+(aq) + OH-(aq)
The addition of hydroxide ion to a solution with ammonium ion shifts the equation to the right.
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How can ammonium gas be detected when heated?
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Mg2+ and Ca2+ can interfere with the confirmatory test for copper ion.
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What reduces copper (II) ion to copper metal?
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The equation for copper ion is ________.
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What is the first confirmatory test for cations?
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What precipitate is produced by the addition of potassium hexacyanoferrate (II)?
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What is the chemical formula for hexacyanoferrate?
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The second confirmatory equation for copper ion is ________.
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What precipitate forms in ammoniacal solution for calcium ion?
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The equation for calcium ion is Ca2+(aq) + __________.
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We are using a __________ for calcium ion.
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What happens after heating magnesium ion with the addition of monohydrogen phosphate ion?
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The equation for magnesium ion is Mg2+(aq) + __________.
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What must cations be separated into?
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All ammonium salts are water soluble.
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Ammonium ion is a strong acid.
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How many hydrogen and nitrogen atoms are present in ammonia?
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What is formed when ammonia accepts a proton?
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Study Notes
Sodium Ion
- Produces a fluffy yellow flame during a flame test.
Potassium Ion
- Flame test viewed with cobalt blue glass shows a lavender color.
Ammonium Ion
- Reaction equation: NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq).
Hydroxide Ion and Ammonium Ion
- Adding hydroxide ion to solution with ammonium ion shifts the equilibrium to the left.
Heating Ammonium Gas
- Presence detected by moist litmus paper when heated.
Copper Ion
- Separation of Mg2+ and Ca2+ is crucial to prevent interference during confirmatory testing.
Reduction of Copper (II) Ion
- Copper (II) ion is reduced to copper metal by the addition of zinc metal.
Copper Reaction Equation
- Cu2+(aq) + Zn(s) ⇢ Cu(s) + Zn2+(aq).
First Confirmatory Test
- Zn2+(aq) does not interfere with Mg2+ and Cu2+ tests.
Second Confirmatory Test
- Potassium hexacyanoferrate (II) creates a red-brownish precipitate Cu2[Fe(CN)6].
Hexacyanoferrate Formula
- K4[Fe(CN)6].
Copper Ion Second Confirmatory Equation
- Equation: 2[Cu(NH3)4]2+(aq) + [Fe(CN)6]4-(aq) ⇢ Cu2Fe(CN)6 + 8NH3(aq).
Calcium Ion
- Forms a white precipitate of calcium oxalate in ammoniacal solution.
Calcium Ion Reaction Equation
- Equation: Ca2+(aq) + C2O42-(aq) ⇢ CaC2O4(s).
Flame Test for Calcium Ion
- Yellow-red flame noted upon dissolution of calcium oxalate.
Magnesium Ion
- White precipitate emerges after heating with monohydrogen phosphate ion (HPO42-) in ammoniacal solution.
Magnesium Ion Reaction Equation
- Equation: Mg2+(aq) + HPO42-(aq) + NH3(aq) ⇢ MgNH4PO4(s).
Cations Grouping
- Cations must be separated into groups based on similar properties.
Solubility of Ammonium Salts
- All ammonium salts are water soluble.
Ammonium Ion Properties
- Acts as a weak acid.
Ammonia and Ammonium Ion Structure
- Ammonia is a gas with three hydrogen atoms and one nitrogen atom; ammonium has four hydrogen atoms and one nitrogen atom (conjugate acid).
Studying That Suits You
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Description
Test your knowledge on various ions and their properties with these flashcards from Chemistry Experiment 38. Each card presents key definitions and reactions involving sodium, potassium, and ammonium ions to reinforce your understanding of flame tests and equilibrium. Perfect for students studying chemistry concepts.
