Analytical Chemistry PHCMp 101

Slides:



Advertisements
Similar presentations
How to predict a Product
Advertisements

Idea of the experiment: (1) Qualitative investigation of [Al +++ ] in a systemic cycle. (2) Preparation of different [Al +++ ] compounds. (3) Inter-conversion.
Chemical Equations Preparation for College Chemistry Columbia University Department of Chemistry.
Precipitation Equilibria. Solubility Product Ionic compounds that we have learned are insoluble in water actually do dissolve a tiny amount. We can quantify.
TESTING FOR CATIONS QUALITATIVE ANALYSIS.
Idea of the experiment: (1) Qualitative investigation of [Zn 2+ ] in a systemic cycle. (2) Preparation of different [Zn 2+ ] compounds. (3) Inter-conversion.
Aqueous Ionic Solutions and Equilibrium Chapter 19.
Flame test Flame Colour Inference Golden yellow Na Lilac (violet) K
Chemistry 123 – Dr. Woodward Qualitative Analysis of Metallic Elements Ag +, Pb 2+, Bi 3+ Cu 2+, Al 3+, Cr 3+ Ni 2+, Co 2+, Zn 2+ Sb 3+ /Sb 5+ Sn 2+ /Sn.
Lecture 92/09/06. A chemistry student mixes 20.0 mL of 4.5 x M AgNO 3 with 10.0 mL of 7.5 x M of NaBrO 3. Will a precipitate of AgBrO 3 form?
Separation and Identification of the Group II Hydroxides in an Unknown
The K sp of chromium (III) iodate in water is 5.0 x Estimate the molar solubility of the compound. Cr(IO 3 ) 3 (s)  Cr 3+ (aq) + 3 IO 3 - (aq)
Solubility Equilibrium In saturated solutions dynamic equilibrium exists between undissolved solids and ionic species in solutions Solids continue to dissolve.
 The ability to dissolve or break down into its component ions in a liquid  Example:  NaCl is soluble  Completely dissolves in water  AgCl is insoluble.
PRECIPITATION REACTIONS Chapter 17 Part 2 2 Insoluble Chlorides All salts formed in this experiment are said to be INSOLUBLE and form precipitates when.
Qualitative Analysis Chemistry 12 AP.
Chapter 18 Solubility and Complex-Ion Equilibria
1 Selective Precipitation  a solution containing several different cations can often be separated by addition of a reagent that will form an insoluble.
Solubility Allows us to flavor foods -- salt & sugar. Solubility of tooth enamel in acids. Allows use of toxic barium sulfate for intestinal x-rays.
Ms Stephens Carry out procedures to identify ions present in solution Qualitative – definitions of solubility Solubility rules Identifying ions Balancing.
FORMULAS hydroxideOH -. FORMULAS sulfateSO 4 2- FORMULAS sulfiteSO 3 2-
Single & Double Replacement, Synthesis and Decomposition
Idea of the experiment: (1) Qualitative investigation of [Pb ++ ] in a systemic cycle. (2) Preparation of different [Pb ++ ] compounds. (3) Inter-conversion.
1 Titration Curve of a Weak Base with a Strong Acid.
Reactions Reference. Solubility Rules 1.All nitrates, acetates, and chlorates are soluble. 2.All chlorides, bromides, and iodides are soluble except for.
Chemistry 1011 Slot 51 Chemistry 1011 TOPIC Solubility Equilibrium TEXT REFERENCE Masterton and Hurley Chapter 16.1.
Net Ionic Equations And A Little Review.
13.2a Developing a Redox table.  the relative reactivity of metals can be used to determine which redox reactions are spontaneous In all redox reactions,
Flame Colour Inference Golden yellow Na Lilac (violet) K Brick – red Ca Crimson Sr Apple green Ba Bluish green Cu Green Borates Livid blue Pb, Sb, Bi The.
Class average for Exam I 70. Fe(OH) 3 Fe 3+ (aq) + 3 OH - (aq) [Fe 3+ ][OH - ] 3 = 1.1 x [y][3y] 3 = 1.1 x If there is another source of.
Qualitative Analysis Determines only the presence (or absence) of a substance Sometimes referred to as “Wet Chemistry” Involves the identification of ions.
Qualitative Analysis Identifying Ions in Solution Qualitative Analysis Identifying Ions in Solution.
CH 8 Chemical Equations and Reactions Section 3 Classifying Chemical Reactions.
E 12 Water and Soil Solve problems relating to removal of heavy –metal ions and phosphates by chemical precipitation
الأستاذة\سارة البلوي. Part (1): Inorganic Qualitative Analysis When an acid, e.g. HCl is made to react with a base, e.g. NaOH, salt, NaCl, and water are.
The Activity Series & Solubility The Activity Series Ranks metals from most to least reactive. –the top are most reactive –the bottom are least reactive.
How to write an answer for AS 2.1. *Important You must write down all Observations You must back these observations up with all ionic equations.
SOLUBILITY – The maximum amount of solute that will dissolve in a specific amount of solvent EQUILIBRIA WITH SALTS SATURATED – A solution where the solid.
Will it all dissolve, and if not, how much?. Looking at dissolving of a salt as an equilibrium. If there is not much solid it will all dissolve. As more.
Solubility Equilibria Will it all dissolve, and if not, how much will?
Chapter FifteenPrentice-Hall ©2002Slide 1 of our slides.
Factors That Affect Solubility 1. For solids, as temperature increases, solubility common-ion effect Use Le Chatelier’s principle. For example, with...
Atoms of different elements combine to form compounds by the formation of new chemical bonds Describe how the transfer of electrons produces cations and.
Solubility Lesson 3 Separating Ions.
Tests for Oxidising / Reducing Agents
Chapter 4 ( ) Reactions in aqueous solution
Predicting Reactions.
Single Replacement, Double Replacement and Combustion Reactions
Fe3+, Al3+, Cr3+, Ni2+, Co2+, Mn2+, Zn2+
Analytical Chemistry PHCMp 101
4TH GROUP OF CATIONS Ba+2, Ca+2, Sr+2.
Single Replacement Reactions
Predicting Reactions.
Activity Series Foothill Chemistry.
1st GROUP OF CATIONS (Ag+,
Reactions in Aqueous Solutions
Qualitative Analysis Identifying Ions in Solution
Speed Dating Speed Dating H Na Speed Dating Speed Dating K Be.
Qualitative Analysis Identifying Ions in Solution
Types of Reactions There are FIVE main types of chemical reactions
GROUP IV CATIONS GROUP IV. and V. CATIONS (Ba+2, Ca+2, Sr+2)
Solubility Equilibria
Friday Bellwork Predict the products of the following reactions and balance the equation. Ca + N2  Cl2 + Fe (iron III)  MgO + CO2.
Dissolve, Dissociate, Ionize, Precipitate
Al(OH)3, Cr(OH)3, Fe(OH)3, NiS, CoS, MnS, ZnS
Solubility & Simultaneous Equilibria Part II: Effect of pH, Complex Ion Formation & Selective Precipitation Jespersen Chap. 18 Sec 3, 4 & 5 Dr. C. Yau.
TESTING FOR CATIONS QUALITATIVE ANALYSIS.
Predicting Reactions.
Group 1 Group 2 Group 3 Group 5 Group 4 Ag+, Pb2+, Hg22+
Presentation transcript:

Analytical Chemistry PHCMp 101 Lab 4 Identification of Group IV Cations Group IV Cations

І ΙΙ ΙΙΙ ΙV V VІ Group reagent Ions Formulae of precipitates Grp Group reagent Ions Formulae of precipitates Distinguishing features І Cold dil HCl Ag+, Pb++,Hg2++ AgCl, PbCl2, Hg2Cl2 Chlorides insoluble in cold dil HCl ΙΙ H2S in presence of HCl (0.2-0.3 M) Subgroup IIA Cu++,Cd++,Hg++,Bi++, Pb++ Subgroup IIB Sn++, Sn4+, Sb3+, As3+, As5+ CuS, CdS, PbS, HgS, Bi2S3, SnS, SnS2, Sb2S3, Sb2S5, Precipitated as Sulfides in acidic medium (0.2-0.3 M HCl) ΙΙΙ NH4OH in Presence of NH4Cl Al3+, Cr3+, Fe3+ Al(OH)3, Cr(OH)3, Fe(OH)3 Precipitated as Hydroxides by NH4OH in presence of excess NH4Cl ΙV H2S in Presence of NH4OH Ni++, Co++, Mn++, Zn++ NiS, CoS, MnS, ZnS Precipitated as Sulfides by H2S from ammoniacal solution in presence of NH4Cl V (NH)2CO3 in presence of NH4OH &NH4Cl Ba++, Ca++, Sr++ BaCO3, SrCO3, CaCO3 Precipitated as Carbonates in alkaline medium by NH4OH in presence of NH4Cl VІ No particular reagent Na+, K+, NH+4 , Mg++ Different precipitated forms Ions not precipitated in previous groups

Group IV cations are: Zn2+ / Mn2+ / Co2+ / Ni2+ Zinc/Manganese/Cobalt/Nickel They are precipitated as sulphides: Zn2+ + H2S ZnS (s) White ppt. Mn2+ + H2S MnS (s) Buff ppt. Co2+ + H2S CoS (s) Black ppt. Ni2+ + H2S NiS (s) Black ppt. Group IV Cations

In the presence of NH4Cl & NH4OH Group Reagent is: H2S In the presence of NH4Cl & NH4OH forming insoluble sulphide salts Group IV Cations

The concentration of the [S-2] should be kept high! WHY? The solubility products of group IV sulphides are higher than those of group II sulphides i.e. group IV sulphides require higher conc. of S-2 for their precipitation. Group IV Cations

HOW? H2S 2H+ + S2- NH4OH OH- + NH4+ NH4OH is added to enhance the ionization of H2S as follows: H2S 2H+ + S2- NH4OH OH- + NH4+ NH4Cl is added to decrease the [OH-] by common ion effect to prevent the precipitation of the Mg(OH)2­ (group VI). NH4OH OH- + NH4+ NH4Cl Cl- + NH4+ Group IV Cations

NH4Cl + xss conc NH4OH + K3Fe(CN)6 If Not, take a new portion sample + xss NH4Cl + xss NH4OH + xss H2S If black ppt. appears CoS or NiS New portion of the sample If White ppt. appears ZnS New portion of the sample White ppt: Zn2+ If Buff ppt. appears MnS New portion of the sample NH4Cl + xss conc NH4OH + K3Fe(CN)6 xss NaOH + 3 drops of H2O2 + Boil CH3COOH + K4Fe(CN)6 If Not, take a new portion Reddish brown ppt : Co2+ Brown ppt: Mn2+ NH4Cl + Conc NH4OH + Drops of DMG Pink ppt : Ni2+ Group IV Cations