EXPERIMENT 2 Qualitative Analysis of Cations Flashcards
Analytical Chemistry Lab Exam
It deals with the identification of elements or groupings of elements in a sample.
Qualitative Chemical Analysis
Qualitative Chemical Analysis
It usually the sample is _________ and a _________ must be made in order that all the constituents may be identified.
Complex Mixture
Systematic Analysis
It is commonly dissolved in water for the determination of anionic consituents may be identified.
Sample
Sample is commonly dissolved in water for the determination of _____________ may be identified.
anionic constituents
Negatively charged elements or groupings of elements.
Anionic Constituents
Positively charged elements or groupings of elements
Cationic Constituents
Qualitative Chemical Analysis
Based on the principle of treating the solution with a _____ of regaents so that each reagent separates a ____________.
Succession
Group of Constituents
Qualitative Chemical Analysis
Has application in different fields especially the production of ____, _____, ____, _____ and ______.
Food, Water, Pesticides, Petrochemicals and Pharmaceuticals
A common experimental method used to identify ions in a mixture involves detection and identification of elements present in an unknown sample.
Qualitative Analysis
Qualitative Analysis: A common experimental method used to identify ions in a mixture involves _______ and _______ of elements present in an unknown sample.
Detection
Identification
It is usually done based on the different chemical and physical properties of the ions.
Qualitative Analysis
Qualitative Analysis: It is usually done based on the different __________ and _________ properties of the ions.
Chemical
Physical
Positive charged ions
Cations
When a given solution contains more than ____ cation, it is important to develop an __________.
One
Identification Scheme
Developer of the most commonly used identification Scheme.
Carl Remigius Fresenius
Test Solutions;
AgNo3, Silver nitrate
Cu(NO3)2, Copper(II) nitrate
Fe(NO3)3, Iron(III) nitrate
Zn(NO3)2, Zinc nitrate
Classic Qualitative Analysis Scheme
- Cations that form insoluble Chlorides
- Has HCl as the group reagent or precipitating agent to separate ________ cations from other groups.
Group 1 Cations
Group 1 Cations; Precipitate can be collected by _______ or ____.
Filtration
Centrifuge
Group 1 Cations:
Ag+, Silver cation
Pb^2+, Lead (II) ion
Hg2^2+, Mercurous ion
Insoluble Chlorides
AgCl, Silver chloride
PbCl2, Lead(II) chloride
Hg2Cl2, Mercury(I) chloride
Classic Qualitative Analysis Scheme
- Cations that form insoluble sulfides
- It has H2S as the group reagent or precipitating agent to separate ________ cations from other groups.
Group 2 Cations
Group 2 Cations: Precipitate can be collected by ______ or _______.
Filtration
Centrifuge
Group 2 Cations
As3+, Arsenic Cation
Bi3+, Bismuth Cation
Cd2+, Cadmium ion
Cu2+, Cupric Ion
Hg2+, Mercuric cation
Sb3+, Antimony cation
Sn2+, Tin(II) ion
Acid- Insoluble Sulfides
As2S3, Arsenic trisulfide
Bi2S3, Bismuth(III) sulfide
CdS, Cadmium sulfide
Cus, Copper sulfide
HgS, Mercury sulfide
Sb2s3, Antimony trisulfide
SnS, Tin(II) sulfide
Classic Qualitative Analysis Scheme
- Cations that form base-insoluble sulfides and hydroxides
- NaOH (Sodium Hydroxide) and NH3 (Ammonia) is added until basic when (NH4)2S Ammonium sulfide to separate ________cations from other groups.
Group 3 Cations
Base insoluble sulfides and Hydroxides
- CoS, Carbonyl sulfide
- FeS, Iron(II) sulfide
- MnS, Manganese(II) sulfide
- NiS, Nickel sulfide
- ZnS, Zinc sulfide
- Al(OH)3, Aluminium hydroxide
- Cr(OH)3, Chromium(III) hydroxide
Group 3 cations
- Co2+, Cobaltous Cation
- Fe2+, iron(II) ion
- Fe3+, Ferric cation
- Mn2+, Manganese cation
- Ni2+, Nickel cation
- Zn2+, Zinc (II) ion
- Al3+, Aluminum ion
- Cr3+, Chromium(III) ion
Classic Qualitative Analysis Scheme
- Cations that form insoluble carbonates and phosphates.
- Has Na2CO3 or (NH4)2HPO4 as the group reagent or precipitating agent to separate ____________ from other Groups
Group 4 Cations
Group 4 Cations
Mg2+, Magnesium cation
Ca2+, Calcium ions
Sr2+, Strontium ion
Ba2+, Barium cation
Insoluble Carbonates (or phosphates)
MgCO3, Magnesium carbonate
CaCo3, Calcium carbonate
SrCO3, Strontium carbonate
BaCO3, Barium carbonate
**Classic Qualitative Analysis Scheme
- All the metal ions that form water-insoluble chlorides, *sulfides, carbonates or phosphates were removed and leaving the alkali metal cations.
Group 5 Cations
Reaction of Silver and HCl
Ag+ + Cl- <=> AgCl (s)
White Precipitate
Reaction of Cu (Copper) and NH3 (Ammonia)
Cu2+ (aq) + 4 NH3 (aq) → [Cu(NH3)4]2+ (aq)
tetraamminecopper(II) → Tetraammine copper (II) ion
Deep blue Decantate
Reaction of [Cu(NH3)4]2+ and K4[Fe(CN)6]
“Tetraammine copper (II) ion and Potassium Ferrocyanide”
2Cu2+ + [Fe(CN)6] 4- → Cu2 [Fe(CN)6]
“Ferrocyanide → Copper (II) Ferrocyanide”
Red-brown Precipitate
Reaction of Iron and KSCN
Fe3+ + SCN - → FeSCN2+
Ferric + THIOCYANATE ION → Ferrothiocyanate
Bloody Red Complex
Reaction of Zinc (Zn) and Potassium Ferrocyanide
(K4 [Fe(CN)6 ])
Zn2+ + K + + [Fe(CN)6 ] 4- → Zn3K2 [Fe(CN)6 ]2 (s)
White, light Green or bluegreen
precipitate
Are achieved by selective precipitation
Separation or Elimination Tests
- subsequent separations may involve differential solubility in water, acid, or base, or performing a redox reaction to convert an ion to a different oxidation state.
Separation or Elimination Tests
involves the addition of a carefully selected reagent to an aqueous mixture of ions, resulting in the precipitation of one or more of the ions, while leaving the rest in solution.
Selective precipitation
Once each ion is isolated, its identity can be confirmed by using a chemical reaction specific to that ion which is known as _________________.
confirmatory test
often involve a color change or formation of a precipitate characteristic of a particular ion
Confirmatory Tests
are most often performed on an ion separated from all others and not on the original sample
Confirmatory Tests
is a laboratory device that is used for the separation of fluids, gas or liquid, based on density.
Centrifuge
Centrifuge is a laboratory device that is used for the separation of fluids, gas or liquid, based on ______.
Density
is a laboratory device that is used for the separation of fluids, gas or liquid, based on density.
Centrifuge
__________is achieved by spinning a vessel containing material at high speed;
Separation
The _______________ pushes heavier materials to the outside of the vessel.
centrifugal force
This apparatus is found in most laboratories From academic to clinical to research and used to purify ____, _______, _____, _____, and _____.
cells, subcellular organelles, viruses, proteins, and nucleic acids.
Make sure that you balance the _____ before you start
Centrifuge
______ is done by placing a test tube or test tube containing __________ opposite to the test tube containing the precipitate in the ____________.
Balancing
water
centrifuge
The ______ should have approximately equal weights
two test tubes
Process of separating by carefully pouring out (without disturbing the solid) the top layer of clear liquid into another container and leaving the lower layer with the solid
Decantation
Decantation
Decantate or ________
Supernatant Liquid
Decantation
Precipitate or _________
Residue