23 Questions
What color precipitate forms when As³⁺ is present in a solution?
reddish brown
Which cations are part of Group III?
All of the above
Adding excess Na₂O₂ should be avoided in the analysis of Group III cations.
True
To identify the presence of Zn²⁺, a white precipitate is formed using ____________.
CH3CSNH2
Match the confirmatory results with the correct cations:
Al³+ = red ppt; 3F NH₃ Cr³+ = blue color that fades rapidly; H₂O₂ Zn²+ = white ppt; CH3CSNH2
What are the two possible outcomes when a white precipitate forms after treatment with ammonia during the Analysis of Group I Cations?
lead oxychloride or silver chloride
Which cations form the sulfides that precipitate in Group II as sulfides?
Hg
Aqua regia dissolves HgS due to the complexing action of the nitrate ion.
False
If acidifying and diluting is properly carried out, the solution will produce a concentration of ___.
0.3F
What is the purpose of making the solution strongly basic?
remove the highly colored chromate or dichromate ions
Which of the following cations are present in the soluble Group V?
All of the above
Ammonium ion will always occur in Group V.
True
The separation of strontium ions from calcium ions is not ________.
complete
What is the scale of operations for volume in semimicro analysis?
1 drop to 1 mL
What apparatus is used for heating a solution in semimicro analysis?
Water bath
PbCl2 is more soluble than AgCl.
False
The process of filtration is replaced by the use of a ________ in the laboratory work of qualitative analysis.
centrifuge
Match the Group I cations with their precipitation color result and last reagent used:
Pb2+ = Yellow precipitate Ag+ = White precipitate Hg22+ = White/gray precipitate
What confirmatory result indicates the presence of CO3^2- ions?
vigorous effervescence with KClO3
How are SO3^2- ions confirmed?
white precipitate with H2O2
What color precipitate indicates the presence of AsO2^- ions?
yellow precipitate with HCl
How are AsO4^3- ions identified?
pink color in the CCl4 layer with CCl4
Which ion causes the etching of glass upon its presence?
F^- ions
This lab introduces students to qualitative analysis, identifying constituents of materials through systematic methods. It covers the scale of operations, including cation analysis and preparation of solutions.
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