# Helping Hand

Topics: Laboratory glassware, Concentration, Spectroscopy Pages: 3 (837 words) Published: May 22, 2013
Beer’s Law Lab
Hanna Beeter
March 15, 2013
Honors Chemistry

Introduction:
In Beer’s law lab the purpose was to find the unknown concentration. The lab included the use of a volumetric flask, pipette, and spectrophotometer. The spectrophotometer played the biggest part in finding the concentration of the unknown. A spectrophotometer is an apparatus for measuring the intensity of light in a part of the spectrum, and is transmitted or emitted on a particular substance. After the number retrieved from the spectrophotometer Beer’s law was used to get the absorbance. The formula was 2-log (% T). This is used in life every day; for example drug companies need this information to see how it affects people.

Molarity is moles of solute/liters of solution. In the lab that formula was used when distributing the solution and already having the molarity. Finding moles for this situation was simply all that needed to happen was multiply the molarity to the liters. The relationship between the concentration and light is when one increases so does the other. This is used in everyday life like doing laundry detergent (knowing the exact amount to put in the washer).

Purpose: The purpose of the lab was to determine the concentration of the unknown solution based on absorbance. To calculate the unknown solution’s molarity, one should have graphed various known measurements of molarity versus absorbance of the copper(II) sulfate solution.

Material:
* Cuvettes
* Pipettes
* Spectrophotometer 20
* Distilled water
* CuSO4
Procedure:
1. Label 4-25 mL volumetric flasks with 0.1M, 0.2M, 0.3M, and 0.5M. 2. Pipette 5 mL of 0.5M solution into 0.1M flask and dilute to the mark, mix. 3. Pipette 10 mL of 0.5M solution into 0.2M flask and dilute to the mark, mix. 4. Pipette 15 mL of 0.5M solution into 0.3M flask and dilute to the mark, mix. 5. Pipette 20 mL of 0.5M solution into 0.4M flask and dilute to the mark,...