Podcast
Questions and Answers
When reacting Al(OH)3 with NaOH and H2O2, the ______ will dissolve while the ppt of Fe(OH)3 will not be dissolved.
When reacting Al(OH)3 with NaOH and H2O2, the ______ will dissolve while the ppt of Fe(OH)3 will not be dissolved.
ppt of Al(OH)3 and Cr(OH)3
In the test for Fe+3, adding NH4SCN results in a ______ color.
In the test for Fe+3, adding NH4SCN results in a ______ color.
blood red
The yellow ppt formed when testing for Cr+3 occurs after adding ______ until acidity.
The yellow ppt formed when testing for Cr+3 occurs after adding ______ until acidity.
diluted acetic acid
When testing for Al+3, a white gelatinous ______ is produced after adding NH4Cl and boiling.
When testing for Al+3, a white gelatinous ______ is produced after adding NH4Cl and boiling.
Signup and view all the answers
The ppt of Fe(OH)3 formed during the reactions appears as ______ in color.
The ppt of Fe(OH)3 formed during the reactions appears as ______ in color.
Signup and view all the answers
A cation is a positive charge ______.
A cation is a positive charge ______.
Signup and view all the answers
Group II A cations include ______, Hg, Cd, and Bi.
Group II A cations include ______, Hg, Cd, and Bi.
Signup and view all the answers
The precipitating reagent for Group II A cations is ______ + H2S.
The precipitating reagent for Group II A cations is ______ + H2S.
Signup and view all the answers
Canary yellow ppt indicates the presence of ______ in Group II A cations.
Canary yellow ppt indicates the presence of ______ in Group II A cations.
Signup and view all the answers
The brown ppt observed belongs to ______ in Group II A cations.
The brown ppt observed belongs to ______ in Group II A cations.
Signup and view all the answers
Black ppt indicates the presence of ______ or Cu+2.
Black ppt indicates the presence of ______ or Cu+2.
Signup and view all the answers
To identify the cations, one may use dil. ______ and dil. H2SO4.
To identify the cations, one may use dil. ______ and dil. H2SO4.
Signup and view all the answers
Cations from Group III include Al+3, Fe+3, and ______.
Cations from Group III include Al+3, Fe+3, and ______.
Signup and view all the answers
1ml c.HCl + 2dps H2O2 will yield the ______
1ml c.HCl + 2dps H2O2 will yield the ______
Signup and view all the answers
If a white ppt is formed, it indicates the presence of ______
If a white ppt is formed, it indicates the presence of ______
Signup and view all the answers
The reagent used to precipitate group III cations is ______ OH.
The reagent used to precipitate group III cations is ______ OH.
Signup and view all the answers
From the solution containing Cu+2, a ______ solution is observed.
From the solution containing Cu+2, a ______ solution is observed.
Signup and view all the answers
To identify Cd+2, the solution must be combined with ______ acid and 1 dp K-ferrocyanide.
To identify Cd+2, the solution must be combined with ______ acid and 1 dp K-ferrocyanide.
Signup and view all the answers
When testing for Cr+3, a ______ precipitate is formed.
When testing for Cr+3, a ______ precipitate is formed.
Signup and view all the answers
If the solution does not dissolve after heating, ______ HCl should be added dropwise.
If the solution does not dissolve after heating, ______ HCl should be added dropwise.
Signup and view all the answers
The mixture of group III cations includes Fe+3, Cr+3, and ______.
The mixture of group III cations includes Fe+3, Cr+3, and ______.
Signup and view all the answers
Study Notes
Cations (Group IIA and Group III)
- Cations are positively charged ions. Represented as X⁺.
- Cations are classified into six groups based on the precipitating reagent used.
Group IIA Cations (Cu²⁺, Hg²⁺, Cd²⁺, Bi³⁺)
- The precipitating reagent is 0.25N HCl + H₂S.
- If a powder is not easily dissolved/ mixed with water, add concentrated HCl dropwise until it dissolves.
- Add an excess of H₂S to the mixture to create an insoluble precipitate.
- The resulting precipitate is analyzed for the presence of specific cations. This includes:
- Canary yellow ppt → Cd²⁺
- Brown ppt → Bi³⁺
- Black ppt → Hg²⁺, Cu²⁺
- A further test, using HNO₃, H₂SO₄ and hydrogen peroxide (H₂O₂) with concentrated HCl will distinguish the specific cation.
Group III Cations (Fe³⁺, Cr³⁺, Al³⁺)
- The precipitating reagent is NH₄OH (NH₃) + 10% NH₄Cl.
- Add concentrated HCl dropwise to the powder if it does not initially dissolve with water.
- Add NH₄Cl + NH₃ until the mixture becomes alkaline
- The resulting precipitate is further analyzed using different reagents:
- White gelatinous ppt → Al(OH)₃
- Reddish brown ppt → Fe(OH)₃
- Gray ppt → Cr(OH)₃
- If further analysis reveals a dissolved solution, further testing will differentiate between Al³⁺, Cr³⁺ and Fe³⁺ ions.
Centrifugation
- Centrifugation is a process used to separate particles of different densities in a mixture.
- Centrifuges spin at high speeds, causing heavier particles to settle to the bottom of the tube, creating a pellet.
- Lighter particles remain suspended above the pellet, which can be separated as a supernatant.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge of cations, specifically focusing on Group IIA and Group III cations and their precipitating reagents. The quiz covers the identification of various cations based on their resulting precipitates and solutions. Determine your understanding of the classification and analysis of these important ions in chemistry.
