Qualitative Analysis Flashcards
What is Qualitative Analysis of a Salt?
A technique used to identify the cation and anion present in a salt by analyzing its physical and chemical properties.
What are the four steps in the Qualitative Analysis of a Salt?
Observation of physical properties. Effect of heat on the salt. Test for anions and cations. Confirmatory tests for cations and anions.
How is the carbonate ion tested in qualitative analysis?
Test with dilute HCl. The gas released turns limewater cloudy.
How is the chloride ion tested in qualitative analysis?
Test with dilute HNO₃ and AgNO₃. It forms a white precipitate.
How is the sulphate ion tested in qualitative analysis?
Test with dilute HCl and BaCl₂. It forms a white precipitate.
How is the nitrate ion tested in qualitative analysis?
Test with dilute H₂SO₄ and FeSO₄
What should be done before performing a confirmatory test for cations
The salt must be dissolved in water first and the color of the aqueous solution should be observed.
Qualitative Analysis for NaOH
Colourless (NH4) white precipitate (insoluble) MC. White precipitate (soluble) ZAP. Insoluble coloured precipitates(Cu Fe² Fe³)
What happens when NH₄⁺ reacts with sodium hydroxide solution?
Ammonia gas is released when the mixture is heated.
What happens when Mg²⁺ and Ca²⁺ react with sodium hydroxide solution?
A white insoluble precipitate forms in excess NaOH.
What happens when Zn²⁺. Al³⁺. and Pb²⁺ react with sodium hydroxide solution?
A white soluble precipitate forms in excess NaOH.
What happens when Cu²⁺ reacts with sodium hydroxide solution?
A blue insoluble precipitate forms in excess NaOH.
Qualitative Analysis for NH3
No reaction (NH4 Ca) white precipitate (insoluble) MAP. White precipitate (soluble) Z. Soluble blue percipitate(Cu). Insoluble coloured precipitates(Fe² Fe³)
What happens when NH₄⁺ and Ca²⁺ react with ammonia solution?
No reaction.
What happens when Mg²⁺. Al³⁺. and Pb²⁺ react with ammonia solution?
A white insoluble precipitate forms in excess NH₃.
What happens when Zn²⁺ reacts with ammonia solution?
A white soluble precipitate forms in excess NH₃.
What happens when Cu²⁺ reacts with ammonia solution?
A blue soluble precipitate forms in excess NH₃.
What happens when Fe²⁺ reacts with ammonia solution?
A green insoluble precipitate forms in excess NH₃.
What happens when Fe³⁺ reacts with ammonia solution?
A brown insoluble precipitate forms in excess NH₃.
How is NH₄⁺ confirmed in a qualitative analysis?
Add Nessler reagent. A brown precipitate is formed.
How is Fe²⁺ confirmed in a qualitative analysis?
Add acidified potassium manganate (VII) KMnO₄ solution. The purple color of the solution is decolorized.
How is Fe³⁺ confirmed in a qualitative analysis?
Add potassium thiocyanate (KSCN) solution. A red solution is formed.
How is Pb²⁺ confirmed in a qualitative analysis?
Add potassium iodide (KI) and heat it up. A yellow precipitate forms.
What is the first step in analyzing an unknown salt?
Observe the color of the salt.
