Back to Course

HSC Chemistry

0% Complete
0/61 Steps
  1. Module 1: Properties and Structure of Matter
    1.1 Properties of Matter
  2. 1.2 Atomic Structure and Atomic Mass
  3. 1.3 Periodicity
  4. 1.4 Bonding
  5. Module 2: Introduction to Quantitative Chemistry
    2.1 Chemical Reactions and Stoichiometry
  6. 2.2 Mole Concept
  7. 2.3 Concentration and Molarity
  8. 2.4 Gas Laws
  9. Module 3: Reactive Chemistry
    3.1 Chemical Reactions
  10. 3.2 Predicting Reactions of Metals
  11. 3.3 Rates of Reactions
  12. Module 4: Drivers of Reactions
    4.1 Energy Changes in Chemical Reactions
  13. 4.2 Enthalpy and Hess's Law
  14. 4.3 Entropy and Gibbs Free Energy
  15. Module 5: Equilibrium and Acid Reactions
    5.1 Static and Dynamic Equilibrium
    5 Topics
  16. 5.2 Factors that Affect Equilibrium
    2 Topics
  17. 5.3 Calculating the Equilibrium Constant
    2 Topics
  18. 5.4 Solution Equilibria
  19. Module 6: Acid/Base Reactions
    6.1 Properties of Acids and Bases
    7 Topics
  20. 6.2 Using Brønsted–Lowry Theory
    2 Topics
  21. 6.3 Quantitative Analysis
    1 Topic
  22. Module 7: Organic Chemistry
    7.1 Nomenclature
    2 Topics
  23. 7.2 Hydrocarbons
    2 Topics
  24. 7.3 Products of Reactions Involving Hydrocarbons
  25. 7.4 Alcohols
    1 Topic
  26. 7.5 Reactions of Organic Acids and Bases
  27. 7.6 Polymers
    2 Topics
  28. Module 8: Applying Chemical Ideas
    8.1 Analysis of Inorganic Substances
    3 Topics
  29. 8.2 Analysis of Organic Substances
  30. 8.3 Chemical Synthesis and Design
  31. Working Scientifically
    Working Scientifically Overview
    1 Topic
Lesson 28, Topic 2
In Progress

Testing for Ions

Lesson Progress
0% Complete

Cation analysis

Qualitative tests can be performed to identify the presence of various cations in solution.

Mg2+, Ca2+, and Ba2+ can be distinguished using several tests. Sulfuric acid produces white precipitates with Ca2+ and Ba2+. Sodium hydroxide produces only a white precipitate with Mg2+. Calcium ions produce an orange-red flame colour and barium ions produce a yellow-green flame colour.

Pb2+ and Ag+ both form white precipitates with HCl. However, PbCl2 is soluble in hot water.

Cu2+ ions form a blue precipitate with NaOH solution. Fe2+ ions form a green precipitate and Fe3+ ions form a brown precipitate with NaOH solution.

Flame tests

When aqueous solutions of various metal ions are atomised in a blue (non-luminous) Bunsen burner flame, they produce a characteristic colour in the flame. There are various methods to practically conduct a flame test.

Flame colour examples: Ba2+ = pale yellow-green, Cu2+ = green, Ca2+ = orange-red.

Anion Analysis

Various acid-base and precipitation reactions can be used to identify various anions.

CO32- and OH ions form alkaline solutions, which can be detected using a pH meter. Nitric acid causes effervescence of CO2 from CO32- ions but not with OH- ions.

Cl forms a white precipitate with Ag+, whereas Br forms a cream precipitate and I- forms a pale-yellow precipitate. AgCl dissolves in dilute ammonia. AgBr dissolves in concentrated ammonia solution. AgI does not dissolve in concentrated ammonia solution.

SO42- precipitates in an acidified solution of Ba2+, but PO43- will not. The phosphate ion will precipitate with barium ions in a solution made alkaline with ammonia solution. Acetate (CH3COO) ions do not precipitate with Ba2+ in acidic or alkaline solutions.