exp7 - CHM171L / A11 Physical Chemistry Laboratory 2 1st...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
CHM171L / A11 Physical Chemistry Laboratory 2 1 st Quarter S.Y. 2010-2011 Photochemistry Calderon, Edna 1 , Palomaria, Ralph Matthew 2 ,Pineda,Jermaine Marianne 2 , Regulacio, Anna Rafaela 2 1 Professor, CHM171L/A11, School of Chemical Engineering, Chemistry and Biotechnology, Mapua Institute of Technology; 2 Student, CHM171L /A11 , School of Chemical Engineering, Chemistry and Biotechnology, Mapua Institute of Technology ABSTRACT This experiment is on the topic of photochemistry. Photochemistry is the study of the interactions between light and atoms or molecules . It describes chemical reactions that proceed with the absorption of light. To visualize the effect of light on chemical reactions is the goal of the experimentation. Photochemical reactions require a light source that emits wavelengths corresponding to an electronic transition in the reactant. It can be noticed here that the area exposed to the sunlight turned blue while the covered portions became white. INTRODUCTION Photochemistry, a sub-discipline of chemistry, is the study of the interactions between light and atoms or molecules. Photochemistry describes chemical reactions that proceeds with the absorption of light. Everyday examples include the degradation of plastics and the formation of vitamin D in sunlight. Light is just another term for electromagnetic radiation, a source of energy. The first law of photochemistry, known as the Grotthuss–Draper law (for chemists Theodor Grotthuss and John W. Draper), states that light must be absorbed by a chemical substance in order for a photochemical reaction to take place. The second law of photochemistry, the Stark-Einstein law, states that for each photon of light absorbed by a chemical system, only one molecule is activated for a photochemical reaction. This law, also known as the photoequivalence law, was derived by Albert Einstein at the time when the quantum (photon) theory of light was being developed. Many chemical reactions occur only when a molecule is provided the necessary "activation energy". A simple example can be the combustion of gasoline (a hydrocarbon) into carbon dioxide and water. In this reaction, the activation energy is provided in the form of heat or a spark. In case of photochemical reactions light provides the activation energy. Simplistically, light is one mechanism for providing the activation energy required for many reactions. If laser light is employed, it is possible to selectively excite a molecule so as to produced a desired electronic and vibrational state. Equally, the emission from a particular Experiment 07 Photochemistry Group 8 │ September 16, 2010 1 of 5
Background image of page 1

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

View Full DocumentRight Arrow Icon
CHM171L / A11 Physical Chemistry Laboratory 2 1 st Quarter S.Y. 2010-2011 state may be selectively monitored, providing a measure of the population of that state. If
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 07/31/2011 for the course CHE-CHM-BT CHM171L taught by Professor Calderon during the Spring '11 term at Mapúa Institute of Technology.

Page1 / 5

exp7 - CHM171L / A11 Physical Chemistry Laboratory 2 1st...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online