Laboratory Experiment 6. Detecting ammonium ions in solution

Lecture



Reagents: solutions of ammonium chloride (or sulfate), sodium hydroxide, indicator paper.

To a test tube secured in a stand containing a solution of ammonium chloride (sulfate), add 1‒2 cm3 of sodium hydroxide solution (Fig. ).

Laboratory Experiment 6. Detecting ammonium ions in solution

Warm the mixture for a few seconds, holding moist indicator paper near the mouth of the test tube (without touching the walls!). Note the change in color.

Draw a conclusion about how ammonium ions can be detected in a solution.

Aim of the experiment:
To detect the presence of ammonium ions (NH₄⁺) in a solution.

Reagents and equipment:

  • Ammonium chloride (NH₄Cl) or ammonium sulfate solution

  • Sodium hydroxide (NaOH) solution

  • Moist phenolphthalein paper

  • Test tube, stand, spirit lamp

Procedure:

  1. Into a test tube secured in a stand, pour about 2 cm³ of NH₄Cl solution.

  2. Add 1–2 cm³ of NaOH solution to it.

  3. Carefully heat the test tube over a spirit lamp for a few seconds.

  4. Hold moist phenolphthalein paper near the mouth of the test tube, without touching the walls of the test tube.

  5. Observe the change in color of the paper.

Observation:
The phenolphthalein paper turns crimson. This means that heating releases ammonia (NH₃), which on contact with the moist paper creates an alkaline environment that changes the color of the indicator.

Chemical reaction:

Laboratory Experiment 6. Detecting ammonium ions in solution

Conclusion:
Ammonium ions can be detected by their reaction with an alkali upon heating. The ammonia released causes a change in the color of the phenolphthalein paper, which indicates the presence of NH₄⁺ in the solution.

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Lectures and tutorial on "Неорганическая химия"

Terms: Неорганическая химия

Chapter I. Introduction to Inorganic Chemistry
1.1. Chemistry. Substance, chemical element, atom
1.2. Simple and complex substances. Substances of molecular and non-molecular structure
1.3. Main classes of inorganic compounds
1.3.1. Oxides
1.3.2. Acids: Classification, Chemical Properties, Nomenclature, Methods of Obtaining Acids
1.3.3. Bases
1.3.4. Salts
1.3.5. Relationships Between Classes of Inorganic Compounds
1.4. Quantitative Characteristics of a Substance
1.5. Basic Laws of Chemistry. The Law of Constant Composition of Matter. The Law of Conservation of Mass of Substances
1.6. Avogadro's Law as One of the Fundamental Laws of Chemistry
1.6.1. Molar concentration of a gas
Chapter II. ATOMIC STRUCTURE AND THE PERIODIC LAW 2.7. Atomic Structure
2.8. The Phenomenon of Radioactivity
2.9. The State of the Electron in the Atom
2.10. The Periodic Law in the Context of Atomic Structure Theory
2.11. Periodicity of changes in the properties of the atoms of chemical elements and of the substances they form
2.12. The significance of D. I. Mendeleev's periodic law and periodic table for the development of science
Chapter III. CHEMICAL BONDING AND THE STRUCTURE OF MATTER 3.13. The nature and types of chemical bonding
3.14. Properties of chemical bonds
14.1. Hybridization of atomic orbitals
Laboratory Experiment 1. Building Models of Molecules of Inorganic and Organic Compounds
3.15. Valence and Oxidation State
3.16. Types of Crystal Structures
3.17. Intermolecular Interaction and Hydrogen Bonding
Chapter IV. CHEMICAL REACTIONS 4.18. Classification and general characteristics of chemical reactions
4.18.1. Oxidation-Reduction Reactions. The Most Important Oxidizing Agents and Reducing Agents.
4.19. Thermal Effects of Chemical Reactions
4.20. The Rate of Chemical Reactions
4.21. Factors Affecting the Rate of Chemical Reactions
Laboratory Experiment 2. Investigating the Effect of Temperature and Acid Concentration on the Rate of Reaction Between Zinc and Hydrochloric Acid
4.21.1. The law of mass action
4.22. Chemical Equilibrium
Practical work 1. Chemical reactions: the ratio of the number and composition of starting substances and reaction products, the oxidation state of atoms, the release or absorption of heat, catalysts, and phase boundaries
Chapter V. CHEMISTRY OF SOLUTIONS 5.23. Dissolution as a Physicochemical Process
5.24. Preparation of Solutions
5.25. Electrolytic dissociation of substances in solutions
5.26. The Concept of the Hydrogen Index (pH) of a Solution. Acidity, Alkalinity
Laboratory Experiment 3. Determining the acidic or basic character of a solution using indicators
5.27. Chemical Properties of Acids, Bases, and Salts in Light of the Theory of Electrolytic Dissociation
Laboratory Experiment 3.1*. Ion Exchange Reactions
5.27.1. Hydrolysis of Salts
Laboratory Experiment 3.2*. Hydrolysis of salts (determining the pH of salt solutions)
Practical Work 2. Studying the Properties of Acids, Bases, and Salts in Light of the Theory of Electrolytic Dissociation
Practical Work 2.1*. Solving experimental problems on the topic "Solution Chemistry"
Chapter VI. NONMETALS. 6.28. General Characteristics of Nonmetals
6.29. Hydrogen as a chemical element
Laboratory Experiment 4. Testing solutions of hydrogen compounds of nonmetals with an indicator
6.29.1. Hydrogen Compounds of Nonmetals and Metals
6.29.2. Hydrogen Peroxide
6.30. Halogens as Chemical Elements
6.31. Compounds of the Halogens
6.32. Group VIA Elements. Oxygen and Sulfur
6.32.1. Ozone
6.33. Hydrogen Compounds of Oxygen and Sulfur
6.34. Oxygen compounds of sulfur
6.35. Sulfuric Acid
Laboratory Experiment 5. Investigating the Chemical Properties of a Dilute Sulfuric Acid Solution
6.36. Group VA Elements. Nitrogen and Phosphorus
6.37. Ammonia: Structure, Physical Properties, Preparation and Uses
Laboratory Experiment 6. Detecting ammonium ions in solution
6.37.1. Nitrogen Oxides NO and NO2
6.38. Nitric acid
6.39. Oxygen-Containing Compounds of Phosphorus
Laboratory Experiment 6.1*. Detecting phosphate ions in solution
6.40. The Most Important Mineral Fertilizers
6.41. Group IVA Elements. Carbon and Silicon
6.42. Carbonic and Silicic Acids, Their Salts
Practical Work 3. Solving Experimental Problems on the Topic "Non-Metals"
Practical work 3.1. Identification of mineral fertilizers
Chapter VII. METALS 7.43. Metals. General Characteristics
7.44. General chemical properties of metals
Laboratory Experiment 7. Reaction of Metals with Acid Solutions
7.45. General methods of obtaining metals
45.1. Obtaining Metals by Electrolysis of Aqueous Salt Solutions
7.46. Alkali Metals
7.47. Group IIA metals of the periodic system
Laboratory Experiment 8. Detection of Calcium Ions in Solution
Aluminum and Its Compounds
Laboratory Experiment 9. Amphoteric Properties of Aluminum Hydroxide
7.48.1. General Characteristics of Group B Metals
7.48.2. General Characteristics of the Acid-Base Properties of Oxides and Hydroxides of Group B Metals
49. Iron and Its Compounds
7.50. The most important compounds of iron
7.50.1. Chromium Compounds in Various Oxidation States
7.50.2. Compounds of Manganese in Various Oxidation States
7.50.3. Applications and Biological Role of Group B Metals and Their Compounds
Laboratory experiment 9.1*. Detection of iron(II) and iron(III) ions in solutions
Practical work 4. Solving experimental problems on the topic "Metals"
Practical work 4.1*. Solving experimental problems on the topic "Metals"
Chapter VIII. Chemical Substances in Human Life and Activity. 8.51. The Role of Chemistry in the Development of Civilization
8.51.1. Chemistry and agriculture
8.51.2 Medicinal Chemistry
8.51.2 Food Chemistry. Food Preparation Techniques, Food Industry
8.52. The Chemical Industry and Chemical Synthesis in the Service of Human Development
53. Ecology. Protecting the Environment from the Harmful Effects of Chemical Substances. "Green Chemistry"
Practical Work 7*. Solving Experimental Problems on the Topic "Preparation and Properties of Inorganic Compounds"
Appendix 1. Electronic Structure of Atoms of Chemical Elements of the Small Periods (I–III)
Appendix 2. Minerals and Their Hardness on the Mohs Scale
Appendix 3. Qualitative reactions
Appendix 4. Solubility table of acids, bases, and salts in water
Answers to Calculation Problems and Tests in Inorganic Chemistry