Beer's Law Lab Report

Title: CHEM 161: Beer’s Law and Analysis of a Sports Drink

Purpose: To use a spectrophotometer to analyze a sample of red sports drink and to determine its molar concentration of Allura Red

Method: Law of Conservation of Matter and Beer’s Law

Procedure: Seattle Central Community College, Chem 161-General Chemistry Lab Manual, Winter 2013

Data:

Part I: Solution Concentration and Absorbance

Concentration of Stock Solution: 3.636 X 10-5 M Allura Red

Convert the molarity of Solution #4 to units of mmol/L then use the dilution equation, M1V1 = M2V2, to calculate the molarities (in mmol/L) for Solutions 1-3.

Solution # | 1 | 2 | 3 | 4 |

Molarity (mmol/L) | 4.545 X 10-3 | 9.090 X 10-3 | 1.818 X 10-2 | 3.636 X 10-2 |

Part II: Finding the max for the Allura Red Solutions

What wavelength of maximum absorption was determined in Part II?

503 nm |

Part III: Measuring Absorbance Values for Standard Solutions and Sports Drink

Solution | Molar Concentration of Allura Red (mmol/L) | Absorbance |

DI Water (Blank) | 0 | 0 |

1 | 0.004545 | 0.218 |

2 | 0.009090 | 0.331 |

3 | 0.01818 | 0.537 |

4 | 0.03636 | 0.922 |

| Absorbance |

Sports Drink (original concentration) | 0.204 |

Sports drink diluted to            % of original concentration | N/A |

Sports drink diluted to            % of original concentration | N/A |

Sports drink diluted to            % of original concentration | N/A |

Calculations

M1V1 = M2V2

(3.636 X 10-2) X 25 = M2 X 50

M2 = 1.818 X 10-2 mmol/L of Solution #3 |

(1.818 X 10-2) X 25 = M2 X 50

M2 = 9.090 X 10-3 mmol/L of Solution #2 |

(9.090 X 10-3) X 25 = M2 X 50

M2 = 4.545 X 10-3 mmol/L of Solution #1 |

Post-Laboratory Calculations and Analysis

1. Linear equation: Provide the equation for the best-fit regression line for your Beer’s Law plot:

y = 26931x |

2. Use Beer’s Law and your line equation in Question #1 to calculate the concentration of the diluted sports drink sample with an...