Spectrophotometry Electromagnetic Radiation = Light What is Light?

Slides:

Advertisements

Similar presentations

Introduction to Spectrophotometry & Beer’s Law

Advertisements

Physics and the Quantum Mechanical Model

Colorimetry & Spectrophotometry.

November 18, Electromagnetic Radiation Objectives At the end of class, you will be able to: List the forms of electromagnetic radiation Find wavelength.

Electromagnetic Spectrum

4-1 Radiant Energy. Waves  Light travels in Waves similar to ocean waves  Light waves are electromagnetic and consist of an electric and magnetic fields.

Chapter Eleven Ultraviolet-Visible Spectrophotometry

Spectrophotometry Chapter 17, Harris

ELECTROMAGNETIC RADIATION

Introduction to Spectrophotometry

Introduction to Spectrophotometry

SPECTROPHOTOMETRY cont.. Application qualitative A Absorbance spectrum.

SOLUTION PREP. AND BEER’S LAW Experiment #1. What is this experiment about? This experiment has 2 parts to it. They are as follows: 1.How to make solutions.

Lecture 2b. Electromagnetic Spectrum Visible range: = nm Ultraviolet: = nm Low energyHigh energy.

Non-Instrumental Methods

Introduction to Instrumental Analysis - Spectrophotometry

Index Unit 03 Electron Configuration Module 01: Light as a Wave Based on the PowerPoints By Mr. Kevin Boudreaux, Angelo State Univerisity U03Mod01 Light.

Light as a Wave OBJECTIVES:

ANALYTICAL CHEMISTRY CHEM 3811 CHAPTER 18 DR. AUGUSTINE OFORI AGYEMAN Assistant professor of chemistry Department of natural sciences Clayton state university.

Electromagnetic Radiation The speed of electromagnetic radiation (speed of light) is constant at x 10 m/s – We’ll express it as 3x10 m/s – The symbol.

12.6 Light and Atomic Spectra

Dilution 2003 Required D. Information Given A student is instructed to determine the concentration of a solution of CoCl 2 based on absorption of light.

Let’s Talk About Beer Beer’s Law and Concentrations.

Introduction to Spectrochemical Methods

SPECTROPHOTOMETRY. Determines concentration of a substance in solution by Measures light absorbed by solution at a specific wavelength by using spectrophotometer.

Chapter 5 in your textbook pp Wave Nature of Light  In the early 1900s scientists observed that certain elements emitted visible light when.

Light and Energy Chemistry I. Classical description of light Light is an electromagnetic wave. Light consists of elementary particles called photons.

Colorimetry & Spectrophotometry

Atomic Emission Spectra

Chapter 13 Section 3 -Quantum mechanical model grew out of the study of light -light consists of electromagnetic radiation -includes radio and UV waves,

Electromagnetic radiation travels through space in the form of a wave, with the distance between two crests of a wave termed a wavelength. At one end.

Electromagnetic Spectrum. Copyright McGraw-Hill The Nature of Light The electromagnetic spectrum includes many different types of radiation. Visible.

Introduction to Spectrophotometry

The Bohr Model for Nitrogen 1. Bohr Model of H Atoms 2.

EQUILIBRIUM CONSTANT DETERMINATION

Light l The study of light led to the development of the quantum mechanical model. l Light is a kind of electromagnetic radiation. l Electromagnetic radiation.

Warm Up  Write the correct answers for the following:  1) 2.00 x m = __________m  2) 1.23 x m = __________nm.

  Examining how much light is absorbed by a compound’s sample at various wavelengths  Spectrum peaks—  Indicates the wavelengths associated with electrons’

SPECTROPHOTOMETRY. Spectrophotometry Determines concentration of a substance in solution –Measures light absorbed by solution at a specific wavelength.

Modern Atomic Model and EMR

Lecture 21 UV/Vis Pick up Lecture Problem 7 This Week in Lab: Work on 1st Synthetic Next Week in Lab: Ch 9 Final Report Due Synthetic #2 PreLab Due.

Introduction to Spectrophotometry & Beer’s Law

Physics and the Quantum Mechanical Model.  Light consists of waves  A wave cycle begins at zero, increases to its highest value (crest), returns to.

Do Now: 1.If you could solve one problem using science, what would it be? 2.What branch of science do you think you would need to use to solve the problem?

11 Instrumental Analysis Tutorial By the end of this session the student should be able to: 1.Use mathematical formulae to calculate absorbance,

Chemistry Physics and the Quantum Mechanical Model.

A darker color means a higher concentration of the colored component

Investigating the relationship between Molar Concentration and Absorbance of Light Beer’s Law Link to spec 20 video.

Introduction to Spectrophotometry

Electrons in Atoms Chapter 4.

Colorimetry GT Chemistry 5/13/15.

Introduction to Spectrophotometry

Quantum Theory and the Electronic Structure of Atoms

Introduction to Spectrophotometry

Light and the Atomic Spectra

Chapter 9 Electronic Structure and Periodic Trends

Spectroscopy Chem honors.

What is this experiment about?

Colorimetry and Beer’s Law

Spectrophotometry For high school Chemistry, AP Chemistry,

Lecture 2b Beer’s Lambert Law.

Waves and Electromagnetic Radiation

Can observe color using absorption spectroscopy (which looks at the intensity of light absorbed versus intensity of light transmitted)

SPECTROPHOTOMETRY Applied Chemistry.

STEP 1 – DETERMINE THE WAVELENGTH OF LIGHT TO USE

Beer's- Lambert Law and Standard Curves of concentrations

2.3 Light Objectives 3 and 5:b

Sample AP Model Drawing Question

5.1 – ELECTRONS IN ATOMS.

Spectrophotometry A method to determine concentration of a species exploiting the absorption of EMR.

Presentation transcript:

Spectrophotometry Electromagnetic Radiation = Light What is Light? Visible light is a particular kind of electromagnetic radiation X-rays, UV, Infrared, Microwaves, and Radio waves are all light forms Light is a form of Energy All light travels in waves at “the speed of light” = c = 3 x 108 m/s 2

Characteristics of Light Wavelength = distance between two peaks in a wave l (lambda) is the symbol Meters = m is the unit Frequency = number of complete waves passing a given point per second n (nu) is the symbol Hertz = Hz = s-1 is the unit Amplitude = A = measure of the intensity of the wave, “brightness” The speed of light is constant: c =  x  l and n are inversely proportional If one increases, the other decreases Their product is always the speed of light = c =  x  = 3 x 108 m/s

II. Spectroscopy = using light to investigate a compound How the experiment works What color do we see? a) What we see as the color of a compound is the complementary color to what the compound absorbs b) Example: Absorbs red, we see green

Beer’s Law Absorbance tells us how much light is absorbed by the molecule B. A = elc (y = mx + b) describes the absorption of light in a solution l = the length of the cell containing the solution, usual 1 cm c = concentration in mol/L = M e = Molar extinction coefficient = constant for a given molecule at a given wavelength of light = how well the molecule absorbs light Percent T 0 10 25 50 75 100 2.0 1.0 0.6 0.3 0.1 0 Absorbance 1.0 0.5 0.0 e ≈ 18,000 for our red dye Absorbance Slope = el [L/mol∙cm][cm] 0 0.00001 0.00002 0.00003 0.00004 0.00005 Concentration (mol/L)

Today’s Experiment Make a Beer’s Law Calibration Curve using a Stock Solution Calculating the concentration of your stock solution: (Ex: 0.0788g/L) Calculations for the calibration curve samples: M1V1 = M2V2 An Excel Template is available at faculty.swosu.edu/tim.hubin in the “Shared Folder” link called “Spectrophotometry Lab Excel sheet” Sample # 1 2 3 4 5 6 mL Dye Stock Soln 0.50 1.00 1.50 2.00 2.50 3.00 mL Water 9.50 9.00 8.50 8.00 7.50 7.00 Molarity

Find the concentration of an unknown sample of the red dye We will give you an unknown amount of the stock solution Dilute it to 25 ml in a volumetric flask Calculate the absorbance (from %T) on the Spec. 20 Use your spreadsheet to calculate the concentration from the absorbance Example Calculation: %T = 15% for your diluted unknown Make 100ml of a solution of a known concentration (2.5 x 10-5 M)

Chromic Acid Splash in Eyes Frayed Electrical Cord Fire