Lab 9-A Photochemical Reaction Lab Report

Lab 9 –A Photochemical Reaction– Lab Report CHM 2045L -Dr. Yavuz Petrowski Name: Click or tap here to enter text. Znumber: Click or tap to enter a date. Requirement: Handwritten lab reports will not be accepted, please type your work for each section. PRELAB Background Purpose of the experiment: The purpose of the experiment is to identify photochemical reactions and compare energy values for different colors of lights. During this experiment we will also analyze the intensity of light on the formation of chemical reactions. Chemical Equation: Explain the chemical equation AgNO3 (aq) + NaCl (aq)  AgCl (s) + NaNO3 (aq) AgCl (s)  Ag (s) + Cl Silver chloride will be produced from a reaction of AgNO 3 and NaCl. AgCl (s) is white crystalline and will decompose by light. Ag (s) is a darkening surface Formulas: Please include all formulas used in this experiment hxc λ -34 Planck’s constant: h= 6.626 x10 J.s Calculation of energy: E= The speed of light: 3 x 108 m/sec Flow Chart: Complete short experimental procedure for this experiment by using information provided in the power point/instructions as well as lab experimental 360 video in a flow diagram format (box and arrow). A flow chart should show the procedure of how experiment is performed correctly step by step process. Flow charts can not be handwritten, copy and paste images will not be graded. Materials:      Desk Lamps with 40 and 60 W bulbs Filter paper Red and Violet films 0.5 M AgNO3 solution 0.5 M NaCl Measure 1-2 mL of the 0.50 M NaCl solution into your small, graduated cylinder, transfer to a clean, labeled test tube. Measure 1-2 mL of the 0.50 M AgNO3 solution into your small, graduated cylinder, transfer to a clean, labeled test tube. Place the Place the lamp with appropriate the 40W and 60W colored films bulb overapproximately the drops 15cm above the on each side. filter paper. With a separate clean pipette, deliverAfter 2 drops of the AgNO3 15 and 30 minutes, solution on top of comment onthe theNaCl amount of spot. Repeat on theunder othereach half of the discoloration of thefilms filter based paper.on the color scale shown With a clean pipette, deliver 2 drops of the NaCl solution into the filter paper marked Record the 40W and 60W on the half-marked observation in red and twothe drops for the halflab report. marked blue. Discard all materials in the correct containers. Waste Collection: Type out the chemicals used in this experiment, their hazards if applicable, and any other safety concerns associated with this experiment. Suggestions:  In left column, list each chemical.  In the right column, briefly safety hazard Chemicals/ Hazards Safety hazard Bulbs Hot Silver Solution Leaves black spots/ Stains NaCl May cause nausea, convulsion or dehydration DATA PROCESS YOU MUST SHOW ALL YOUR CALCULATIONS TO RECEIVE CREDIT FOR THEM! Hand written calculations and reports will not be graded. Proper use of significant figures and units is part of the grading. PART I: OBSERVATIONS: Record observations from 360 experimental video about the amount of discoloration under each of the films based on the color scale shown below. Record your observations in this lab report. Time, min 40 W RED 60 W BLUE RED BLUE 15 min 0 1 0 2 30 min 0 1 2 5 PART II: CALCULATIONS Calculate the energies for the red and violet films by using: E= -34 Planck’s constant, h= 6.626 x10 J.s c is the speed of light, 3 x 108 m/sec Wavelength for violet film: 450 nm Wavelength for red film: 650 nm Conversion 1 nm= 1 x10-9m hxc λ Calculation: Show all your calculations with correct sig. fig. and units. If the calculation is involving conversions, you must show each individual conversion. All work has to be typed! Hand written calculations will not be accepted. Red Film Energy: 3.05 x 10-19- J Violet Film Energy: 4.97 x 10-19 J Work for red film 650 nm x 1m/ 1 x 10-9 nm = 6.50 x 10-7 m (6.626 x 10-34 J*s) (3.00 x 108 m/s) / (6.50 x 10-7 m) = 3.05 x 10-7 J Work for violet film 400 nm x 1m/ 1 x 10-9 nm = 4.0 x 10-7 m E= (6.626 x 10-34 J*s) (3.00 x 108 m/s) / (4.00 x 10-7 m) = 4.97 x 10-19 J DISCUSSION QUESTIONS 1. Silver iodide is a photosensitive compound that decomposes when exposed to light. The equation for this decomposition is given below: 2AgI  2Ag + I2 Please write balanced oxidation and reduction half-reactions: oxidation half-reaction: 2I-1 - 2e-  2I reduction half-reaction: 2Ag+1 +2e  2Ag 2. What is the wavelength of a photon that has an energy of 7.863 x104 J. Please show your work with correct sig. fig. and units (Work needs to be typed). (6.626 x 10-34 x 3.0 x 108 m/s ) m / 7.863 x104 J = (6.626 x 10-30 x 3.0) x (3) / 7.863 = (19.88/7.863) = Answer: 2.528 x 10-30 m 3. According to the observations you have captured from 360 video: a. Which color wavelength allows more discoloration? Blue shows a bigger increase in energy from red and that allows for more discoloration. Energy reduces as wavelength increases, meaning that smaller wavelengths result in higher energy. There is an inverse relationship that affects the blue and red wavelengths. b. Which one, intensity or wavelength, had more of an effect on inducing a reaction of silver salts. Intensity has more of an effect on inducing a reaction of silver salts because as light intensity increases reactant molecules become more excited and the speed rises. This can have a reaction with more force than the wavelength. 4. Record the percent transmission values from the graphs (see below) provided: Red Transmittance Value: 68 Violet Transmittance Value: 45 Clear Transmittance Value: 99