221-chapter-27

# 221-chapter-27 - Gravimetric Analysis Introduction 1...

This preview shows pages 1–8. Sign up to view the full content.

Gravimetric Analysis Introduction 1.) Gravimetric Analysis: (i) A technique in which the amount of an analyte in a sample is determined by converting the analyte to some product Mass of product can be easily measured (ii) Analyte : the compound or species to be analyzed in a sample (iii) Overall, gravimetry sounds simple. Advantages - when done correctly is highly accurate (most accurate of all time); requires minimal equipment Disadvantage - requires skilled operator, slow. Convert analyte into a solid, filter, weigh, calculate via a mole map

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Introduction 1.) Gravimetric Analysis: (iii) Example: Determination of lead (Pb +2 ) in water Reagent Analyte Solid Product Gravimetric Analysis
Gravimetric Analysis Introduction 1.) Gravimetric Analysis: (v) Example: What is the %KCl in a solid if 5.1367 g of solid gives rise to 0.8246 g AgCl?

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Gravimetric Analysis Types of Gravimetric Analysis 1.) Combustion Analysis 2.) Precipitation Combustion Analysis Common method used to determine the amount of carbon and hydrogen One modified method (Dumas Method ) can also determine the amount of nitrogen in a sample Technique is accurate and usable with a wide range of compounds. Often one of the first methods used to characterize a new compound
Combustion Analysis 1.) Principals: (i) Sample is heated in presence of Oxygen (O 2 ) Converts carbon in sample to CO 2 Converts hydrogen in sample to H 2 O C (sample) + O 2 CO 2 2H (sample) + ½O 2 H 2 O Pt, CuO, PbO 2 , or MnO 2 is used as a catalyst in this process (ii) As CO 2 and H 2 O form, leave the sample and flow through a series of chambers Chambers contain chemicals that bind one or both of these products Example: - P O can be used to absorb H O - Ascarite can be used to absorb CO Gravimetric Analysis Pt Pt Ascarite

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Gravimetric Analysis Combustion Analysis 2.) Apparatus: (i) After the sample is completely burned: Remove P 4 O 10 and Ascarite cartridges and weigh If C and H are present in sample, both cartridges will increase in mass (ii) Amount of C and H in the original sample is determined from: Knowing the amount of sample burned Change in weight in each cartridge
Combustion Analysis 2.) Example Calculation: A mixture weighing 7.290 mg contained only cyclohexane, C 6 H 12 (FM 84.159), and oxirane, C 2 H

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 05/09/2010 for the course CHEM 221 taught by Professor Dr.robertpowers during the Fall '07 term at San Diego.

### Page1 / 22

221-chapter-27 - Gravimetric Analysis Introduction 1...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online