QUALITATIVE AND QUANTITATIVE ELEMENTAL ANAYSIS

Slides:



Advertisements
Similar presentations
Types of Reactions 7.2.
Advertisements

Chapter 4: Chemical Reactions
SALT MODULE 2.
Chapter 4 Reactions in Aqueous Solutions
Chapter 4: Aqueous Reactions Solution: Solvent: substance present in the larger amount Solute: substance(s) dissolved in solvent, generally present in.
Reactions in Aqueous Solutions
PREPARATION & COLLECTION OF NON-METAL COMPOUNDS UNLESS YOU TRY TO DO SOMETHING BEYOND WHAT YOU HAVE ALREADY MASTERED, YOU WILL NEVER GROW. RALPH WALSO.
1 Solution Stoichiometry The concentration of a solution is the amount of solute present in a given quantity of solvent or solution. M = molarity = moles.
Solutions are homogeneous mixtures consisting of two or more components. The major component of a solution is known as the solvent and the minor component.
Concentration of Solutions
Making Salts Soluble salt Insoluble salt Acid + excess insoluble solid
Titrations Titrations A. Titrations – is an experimental procedure in which a standard solution is used to determine the concentration of an unknown.
Quantitative Relationships (Stoichiometry). Lets take a moment… sit back… relax… and review some previously learned concepts… Lets take a moment… sit.
Making Changes Topic overview. The topic can be conveniently split into six interrelated sections  Oxidation/Reduction  Salts  Preparation of gases.
If you are traveling at 65 mi/h how long will it take to travel 112 km? If your car gets 28 miles per gallon how many liters of gas will it take to travel.
Prepared by PhD Halina Falfushynska 1 Lecture 7. Electrolytes. Reactions in Aqueous Solutions.
Stoichiometry Calculations based on chemical reactions.
1.1.2 Moles and equations This Powerpoint contains the questions and answers for the activities 1-20.
1. Some basic chemical reactions are given below. IIICALCULATIONS ON REACTIONS (a) Reactive metal + H 2 O (l)  metal hydroxide + H 2 (g) (Metals above.
A cids Bases & Salts (Salts) an e-learning series by ycs.
Salts.
Qualitative Test for Elements in Organic Compounds
Gravimetric analysis Four example problems 1.Determining salt in foodDetermining salt in food 2.Determining sulfate and sulfur content in fertiliserDetermining.
Calculations in Chemistry- part 2. Molar volume What is the mass of: 600cm^3 of Ammonia gas NH 3 at RTP? 0.43g 1000mL of Methane CH 4 gas at RTP? 0.67g.
Making Salts Insoluble salts – precipitation Mix two solutions together one with the cation, one with the anion. Filter, wash and dry. Soluble Na +, K.
REACTION STOICHIOMETRY 1792 JEREMIAS RICHTER The amount of substances produced or consumed in chemical reactions can be quantified 4F-1 (of 14)
Learning objective: To calculate expected and percentage yield 09/06/2016 On whiteboards…
Chapter 9 Chemical Quantities. 2 cup brownie mix + ½ c H 2 O + ¼c oil + 2 eggs  24 brownies What other items require a recipe? What do the numbers in.
Chemical Analysis Chemical analysis is divided into two main classes: І - Qualitative Analysis: This type of analysis involves the investigation and identification.
Reactions in Aqueous Solutions Chapter 4. Objectives 2.0 Define key terms and concepts. 2.6 Calculate the concentration of a solution. 2.7 Determine if.
Oxygen and oxides. Air is a mixture of gases which contains 4/5 nitrogen 1/5 oxygen.
Chemical Changes and Structure
C3 Calculation Practice
TITRATIONS LESSON OBJECTIVE At the end of the lesson you should be able to perform acid-base titrations, and carry out structured calculations.
Acids and Alkalis.
(A) GETTING THE MOST FROM REACTANTS
Acids, bases & salts Revision.
Great and Glorious Test Day
Stoichiometry I Chapter 11.
==========================
Chemical Calculations
Law of Multiple Proportions: If two elements combine to form more than one compound, the amounts of one element that combine with a fixed amount of the.
Tests for Oxidising / Reducing Agents
Acids & Bases.
Acids and Alkalis Grade 10.
12.6 – How can we use ions in solutions?
Determination of Total Nitrogen By Kjeldahl’s Method
Chemical Quantities and Aqueous Reactions
Chemical Equations Writing and balancing.
Bell Work 1 / Balancing Equations
Chapter 10 Chemical Reactions.
Types of solution stoichiometry problems
Chemical Reactions.
Chemical Reactions/Stoichiometry
Classification of Chemical Reactions
Chemical Equilibrium and pH
Aqueous Solutions Pt. 2.
Unit 4: Chemical Equations and Stoichiometry
Gravimetric Analysis Determining information about a species by performing a reaction and measuring how much product was formed. Involves the creation.
Unit 4: Chemical Equations and Stoichiometry
Transition elements Copper
Qualitative analysis of organic compounds.
Titration of Mixtures of Acids Using a Strong Base For two acids to titrate separately, the ka of the stronger one should be at least 104 times greater.
Transition elements Chromium
Transition elements Nickel
On the back, write down everything this tells you
Determination of Nitrogen By Kjeldahl’s Method
TESTING FOR CATIONS QUALITATIVE ANALYSIS.
ANALYSIS OF COMPUNDS B.Sc. Sneha S. Mule Assistant Professor
MAKING SALTS 21/06/2019.
Presentation transcript:

QUALITATIVE AND QUANTITATIVE ELEMENTAL ANAYSIS           QUALITATIVE AND QUANTITATIVE ELEMENTAL ANAYSIS by SHITTU T.O. is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. QUALITATIVE AND QUANTITATIVE ELEMENTAL ANAYSIS

Learning goals At the end of the lecture, you should be able to: a). Describe qualitative tests for specific elements in organic sample b). Carry out basic calculations in quantitative elemental analysis.

Qualitative elemental analysis This method deals with identification of various elements present in an organic sample. Most organic samples contain C, H ,O and other elements such as N, P, S, halogens and metals.

Detection of C and H C & H can be detected in an organic sample by heating the sample with cupric oxide (CUO) in a combustion tube. Sample+ CUO CO2(g) + H2O(g) CO2 turns lime water milky. H2O turns anhydrous CUSO4 from white to blue or anhydrous CoCl2 fom blue to pink.

Detection of N, S and halogens N, S and halogens can be detected in an organic sample by using Lassaigne’s sodium fusion test. This method converts elements in the organic sample into soluble sodium compound by fusion with sodium metal. [C,H,N,X,P, S] Na (excess) NaCN + Na2S + NaX If limited sodium is used, sodiumthiosulphate is formed instead of sodiumcyanide [C,H,N,X,P, S] Na (limited) NaSCN + NaX Na   NaCN + Na2S

Sodium fusion test cont’d Further work-ups and analyses will then lead to identification of S, Br, I, Cl or N.

Quantitative elemental analysis This deals with estimation of the proportion by mass or % of the element in a given mass of organic sample.

Quantitative determination of C and H A known mass of the organic compound is burned in excess O2, where C and H are converted to CO2 and H2O respectively. Apparatus for determining C & H Source: http://www.tutorvista.com/content/chemistry

The CO2 is absorbed in soda lime (KOH) and weighed. H2O is absorbed in CaCl2 and also weighed. The % C and H can then be determined.

Question 1 1.62g of an unknown organic compound containing only carbon, hydrogen and oxygen, gave 2.64g of CO2 and 0.9g of H2O on complete combustion. i. Determine the empirical formula of the compound. ii. What is the molecular formula of the compound given if its relative molecular mass is 180

Quantitative determination of nitrogen i. Kjeldahl method ii. Dumas method Kjeldahl method This method is used for quantitative determination of nitrogen in samples such as protein, amines and other nitrogen containing compounds. The sample is digested by heating it with sulphuric acid in the presence of a catalyst such as Cu or Se. The resulting mixture is made alkaline by addition of NaOH. The volume of NH3(g) liberated is then determined by volumetric analysis by titrating NH3 formed with a standard H2SO4 or HCl, using a suitable indicator.

Equation of reaction for titration: NH3(g) + H2SO4 (aq) (NH4)2SO4(aq)

Dumas method: This method converts the nitrogen in the organic sample to gaseous nitrogen(N2). A known mass of the compound is heated with excess Cu2O in the absence of air. The gases produced are passed over heated Cu to decompose any oxide of nitrogen into gaseous nitrogen. The nitrogen is collected in a nitrometer. The volume of nitrogen collected is then converted to that at S.T.P Mole= 𝑉𝑁2 𝑎𝑡 𝑆.𝑇.𝑃 𝑑𝑚3 22.4𝑑𝑚3

Question 1.4g sample of a newly isolated organic compound was subjected to kjeldahl analysis. The gas produced was neutralized by 26.3cm3 of 0.25M sulphuric acid. (a). name the gas produced in this analysis (b). Calculate the percentage of nitrogen in the organic sample. (N= 14.0, H= 1.0)

Question 3: 0.14g of an organic sample on suitable treatment gave 27.44cm3 of nitrogen measured at STP. What is the percentage of nitrogen in the sample

Quantitative determination of sulphur and halogens Sulphur and halogens can be quantitatively determined by gravimetric analysis using Carius method. Under suitable treatment, the S in the sample is converted to BaSO4 and halogens to AgX (X = Cl, Br, I e.t.c.)

A 0. 8g sample gave 1. 2 g of BaSO4 in a gravimetric analysis A 0.8g sample gave 1.2 g of BaSO4 in a gravimetric analysis. What is the % of S in the sample.

Practice question The molecular mass of an organic compound containing C, H and N was found to be 59. on combustion, 0.13g of the compound gave 0.29g of CO2 and 0.18g of H2O. 0.145g of the compound on suitable treatment gave 27cm3 of N2 measured at S.T.P. Deduce the structure possible structures of the compound.

QUALITATIVE AND QUANTITATIVE ELEMENTAL ANAYSIS

Learning goals At the end of the lecture, you should be able to: a). Describe qualitative tests for specific elements in organic sample b). Carry out basic calculations in quantitative elemental analysis.

Qualitative elemental analysis This method deals with identification of various elements present in an organic sample. Most organic samples contain C, H ,O and other elements such as N, P, S, halogens and metals.

Detection of C and H C & H can be detected in an organic sample by heating the sample with cupric oxide (CUO) in a combustion tube. Sample+ CUO CO2(g) + H2O(g) CO2 turns lime water milky. H2O turns anhydrous CUSO4 from white to blue or anhydrous CoCl2 fom blue to pink.

Detection of N, S and halogens N, S and halogens can be detected in an organic sample by using Lassaigne’s sodium fusion test. This method converts elements in the oragnic sample into soluble sodium compound by fusion with sodium metal. [C,H,N,X,P, S] Na (excess) NaCN + Na2S + NaX If limited sodium is used, sodiumthiosulphate is formed instead of sodiumcyanide [C,H,N,X,P, S] Na (limited) NaSCN + NaX Na   NaCN + Na2S

Procedure in Lassaigne’s sodium fusion test The sample is heated with excess sodium metal to redness. The heated sample is and plugged into water and then ground in a mortar. The content is allowed to cool and then filtered. Test for nitrogen: Lassaignes fitrate + FeSO4(aq) Na4Fe(CN)6(aq) + Na2SO4(aq) 3Na4Fe(CN)6(aq) + 4FeCl3 (aq) Fe4[Fe(CN)6]3(aq)+ 12NaCl prussian blue solution

Test for sulfur Na2S (Lassaignes fitrate )+ dil. Pb[CH3COO]2 + dilute CH3COOH PbS (black ppt) + 2CH3COONa

Test for halogens To test for halogens, Lassaignes fitrate is first acidified with few drops of dilute H2SO4 and boiled to remove S And CN in the form of HCN(g) and H2S(g). These S2- and CN- ions can also interfere with the precipitating agents such as AgNO3 NaX + AgNO3 dil.HNO3 NaNO3 + AgX White ppt soluble in excess aqueous NH3, it indicates the presence of Cl- present Pale yellow ppt sparingly soluble in excess aqueous NH3, it indicates the presence of Br- present yellow ppt insoluble in excess aqueous NH3, it indicates the presence of I- present

Quantitative elemental analysis This deals with estimation of the proportion by mass or % of the element in a given mass of organic sample. Quantitative determination of C and H A known mass of the organic compound is burnt in excess O2, where C and H are converted to CO2 and H2O respectively. The CO2 is absorbed in soda lime (KOH) and weighed. H2O is absorbed in CaCl2 and also weighed. The % C and H can then be determined.

Question 1 1.62g of an unknown organic compound containing only Carbon, hydrogen and oxygen, gave 2.64g of CO2 and 0.9g of H2O on complete combustion. i. Determine the empirical formula of the compound. ii. What is the molecular formula of the compound given if its relative molecular mass is 180

Quantitative determination of nitrogen i. Kjeldahl method ii. Dumas method Kjedahl method this method is used for quantitative determination of nitrgen in samples such as protein, amines and other nitrogen containing compounds. The sample is digested by heating it with sulphuric acid in the presence of a catalyst such as Cu or Se. the digestion converts the nitrogen in the sample to ammonia. The ammonia gas formed is not liberated in acid solution due to the presence of SO42-. The solution is made alkaline by reacting NaOH, which converts it to NH3. The volume of NH3(g) liberted is then determined by volumetric analysis by titrating NH3 formed with a standard H2SO4 or HCl, using a suitable indicator. Equation of titration for titration: NH3(g) + H2SO4 (aq) (NH4)2SO4(aq)

Dumas method: This method converts the nitrogen in the organic sample to gaseous nitrogen(N2). A known mass of the compound is heated with excess Cu2O in the absence of air. The gases produced are passed over heated Cu to decompose any oxide of nitrogen into gaseous nitrogen. All the gases produced are then passes through concentrated KOH to remove all the gases except N2. the nitrogen is collected in a nitrometer. The vloume of nitrogen collected is then converted to that a S.T.P Mole= 𝑉𝑁2 𝑎𝑡 𝑆.𝑇.𝑃 𝑑𝑚3 22.4𝑑𝑚3

Question 2 1.4g sample of a newly isolated organic compound was subjected to kjedahl analysis. The gas produced was neutralized by 26.3cm3 of 0.25M sulphuric acid. (a). name the gas produced in this analysis (b). Calculate the percentage of nitrogen in the organic sample. (N= 14.0, H= 1.0)

Question 3: 0.14g of an organic sample on suitable treatment gave 27.44cm3 of nitrogen measured at STP. What is the percentage of nitrogen by mass of nitrogen.

Quantitative determination of sulphur and halogens Sulphur and halogen can be quantitatively determined by gravimetric analysis using Carius method. The precipitate formed is washed, filtered, dried and weighed. Under suitable treatment, the S in an sample is converted to BaSO4 and halogens to AgX

QUALITATIVE AND QUANTITATIVE ELEMENTAL ANAYSIS by SHITTU T. O           QUALITATIVE AND QUANTITATIVE ELEMENTAL ANAYSIS by SHITTU T.O. is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Practice questions The molecular mass of an organic compound containing C, H and N was found to be 59. on combustion, 0.13g of the compound gave 0.29g of CO2 and 0.18g of H2O. 0.145g of the compound on suitable treatment gave 27cm3 of N2 measured at S.T.P. Deduce the structure possible structures of the compound.