Background
The scientific concepts involved in this lab include Spectroscopy, Beer’s law, Calibration curve, concentration, and electronic transitions. The main objective of this experiment is to see how the percent composition of brass can be determined to verify the properties influenced by copper and zinc. Brass is a generic term for alloys of copper and zinc. The main technique used in this experiment is Spectroscopy. The three equations used in this lab are:
Y = mx + b, where y = absorbance, x = concentration, and b = 0 using a calibration curve to establish the range of concentration values over which Beer’s law is valid
A=Ɛbc, where A = absorbance, Ɛ = molar absorptivity, b = path length, and c = concentration
Absorbance is defined as a measure of the capacity of a substance to absorb light of a specified wavelength. Concentration is defined as the amount of solute per unit volume of solution. Beer’s law is defined as a method that relates the absorption of light to the properties of the material through which one substance like light is traveling. Calibration Curve is defined as a general method for determining the concentration of a substance in an unknown sample by comparing the unknown to a set of standard samples of known concentration.
Purpose
The purpose of this lab is to design a procedure to analyze the amount of copper in brass using visible spectroscopy.
Pre-lab 1 – 3
Safety
Concentrated Nitric acid is severely corrosive
Reactions of Nitric acid with metals generate nitrogen dioxide, a toxic, reddish-brown gas.
Work with Nitric acid in the fume hood
Copper(II) Sulfate, Copper(II) Nitrate, and Zinc Nitrate solutions are toxic and irritating to body tissue
Zinc Sulfate is a mild body tissue irritant
Wear chemical splash goggles, chemical resistant gloves, and a chemical-resistant apron
Wash hands thoroughly with soap and water before leaving the laboratory
Data chart for introductory activity