# Fundamentals for Chemistry-Quantitative Measurements

1681 Words Jun 30th, 2013 7 Pages
1 Lab Assignment #5 Write-Up

2

General Info:
Name:
Date:

Purpose: Of Exp #5: In this experiment we will learn about the spectroscope and how it works. To learn the concept of quantitative measurements, to construct a spectroscope and, to use it for taking quantitative measurements.

Experimental Questions:
Please complete this section of your write-up as you work on the experimental portion of this lab.

1. Hold the grating several inches from your face, at an angle. Look at the grating that you will be using. Describe what you see at the grating surface. I see different color of the rainbow and when I change the angle that am holding the diffraction grating

Hold the grating up to your eye and look through it.
How many spaces from the center of violet line to center of green line? 2 spaces. How many spaces from the center of violet line to center of yellow line? 3 spaces.

4. Finding the nm/space for your spectroscope:

= difference in wavelength /# of spaces between two lines

Using the violet and green lines: =(538nm-436nm)/( 2 ) = 50 nm/space (value#1)

Using the violet and yellow lines: =(580nm-436nm)/( 3 ) = 48 nm/space (value#2)

Average nm/space: = (Value #1 +Value #2)/2 = (50+48)/2 = 49 nm/space

Agreement of the two values: % difference = 100 x |value 1 – value 2|/(average value) = 100 x | 50 - 48 |/( 49 ) =4.1%

is this value < 10%__Yes_.( go through calibration process until you can say “yes.”)

Your spectroscope is now calibrated. Do not move the light rod – tape in place with clear tape if you have not yet done so. In event that light rod moves, place reference mark in center of violet line, and re-secure light rod.

Questions and Conclusions:
Now that you better understand the functioning of a spectroscope, answer the following questions.

1. What is white light? White light is mixture of all color in spectra.

What experimental evidence do you personally have to support this idea? ( By looking to the white light (light source) of my