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Practical Work 7*. Solving Experimental Problems on the Topic "Preparation and Properties of Inorganic Compounds"

Lecture



1. Obtain a gas and prove its presence, using:

  • a) zinc and hydrochloric acid;
  • b) calcium carbonate and hydrochloric acid.

2. Using the scheme given, obtain a metal hydroxide and prove that it reacts with acids:

  • a) MgCl2 Practical Work 7*. Solving Experimental Problems on the Topic Preparation and Properties of Inorganic Compounds Mg(OH)2 Practical Work 7*. Solving Experimental Problems on the Topic Preparation and Properties of Inorganic Compounds …;
  • b) CuCl2 Practical Work 7*. Solving Experimental Problems on the Topic Preparation and Properties of Inorganic Compounds Cu(OH)2 Practical Work 7*. Solving Experimental Problems on the Topic Preparation and Properties of Inorganic Compounds ….;

3. From the reagents provided to you, obtain an insoluble carbonate:

  • a) CaCO3;
  • b) ZnCO3.

Prove that it reacts with hydrochloric acid.

4. Test solutions of the following salts with universal indicator:

  • a) KCl and AlCl3;
  • b) K2SO3 and KCl.

Compare and explain the results of the investigation.

5. Prove that the solution given to you contains the salt:

  • a) iron(III) chloride;
  • b) calcium chloride.

In your report, present the reaction equations in molecular, full ionic, and net ionic forms.

1. Obtaining a gas and proving its presence

a) Zinc and hydrochloric acid

Reaction:
Molecular equation:
Zn + 2HCl → ZnCl₂ + H₂↑

Observation: A colorless gas (hydrogen) is evolved, accompanied by hissing.
Proof: Bringing a lit splint close — a "pop test" (a small pop sound) occurs — a sign of hydrogen.


b) Calcium carbonate and hydrochloric acid

Reaction:
Molecular equation:
CaCO₃ + 2HCl → CaCl₂ + CO₂↑ + H₂O

Observation: Vigorous gas evolution occurs.
Proof: Passing the gas through limewater:
CO₂ + Ca(OH)₂ → CaCO₃↓ + H₂O — turbidity of the limewater confirms the presence of carbon dioxide.


2. Obtaining a metal hydroxide and proving its amphoteric nature

a)

Scheme:
MgCl₂ + 2NaOH → Mg(OH)₂↓ + 2NaCl
Next:
Mg(OH)₂ + 2HCl → MgCl₂ + 2H₂O

Observation: The white precipitate dissolves in the acid — proof that Mg(OH)₂ reacts with the acid.


b)

Scheme:
CuCl₂ + 2NaOH → Cu(OH)₂↓ + 2NaCl
Next:
Cu(OH)₂ + 2HCl → CuCl₂ + 2H₂O

Observation: The blue precipitate dissolves — a neutralization reaction.


3. Obtaining an insoluble carbonate and its reaction with HCl

a)

CaCl₂ + Na₂CO₃ → CaCO₃↓ + 2NaCl
CaCO₃ + 2HCl → CaCl₂ + CO₂↑ + H₂O

Observation: The precipitate dissolves, and gas — CO₂ — is evolved.


b)

ZnCl₂ + Na₂CO₃ → ZnCO₃↓ + 2NaCl
ZnCO₃ + 2HCl → ZnCl₂ + CO₂↑ + H₂O


4. Testing with universal indicator

a) KCl — neutral salt, pH ~ 7

AlCl₃ — undergoes hydrolysis, pH < 7 (acidic medium)

Explanation:
Al³⁺ + 3H₂O ⇌ [Al(H₂O)₆]³⁺ ⇌ Al(OH)₃ + 3H⁺ — acidification of the medium.


b) K₂SO₃ — weakly alkaline salt (SO₃²⁻ + H₂O ⇌ HSO₃⁻ + OH⁻), pH > 7

KCl — neutral salt, pH ~ 7


5. Proving the presence of a salt

a) Iron(III) chloride

Molecular:
FeCl₃ + 3NaOH → Fe(OH)₃↓ + 3NaCl
Full ionic:
Fe³⁺ + 3Cl⁻ + 3Na⁺ + 3OH⁻ → Fe(OH)₃↓ + 3Na⁺ + 3Cl⁻
Net ionic:
Fe³⁺ + 3OH⁻ → Fe(OH)₃↓

Observation: A red-brown precipitate — proof of the presence of Fe³⁺ ions.


b) Calcium chloride

Molecular:
CaCl₂ + Na₂CO₃ → CaCO₃↓ + 2NaCl
Full ionic:
Ca²⁺ + 2Cl⁻ + 2Na⁺ + CO₃²⁻ → CaCO₃↓ + 2Na⁺ + 2Cl⁻
Net ionic:
Ca²⁺ + CO₃²⁻ → CaCO₃↓

Observation: A white precipitate — confirmation of the presence of Ca²⁺ ions.

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Lectures and tutorial on "Неорганическая химия"

Terms: Неорганическая химия