Molarity Lab Report

Introduction: Molarity (M) is used to determine concentration. Molarity is found by dividing the number of moles of a solute by the volume of the solution in liters. Multiple series of solutions with different concentrations can be used by diluting the concentration. The dilution technique is: Number Moles Concentrated Solution = Number Moles Dilute Solution. An instrument called a spectrophotometer detects the amount of light that passes through the sample and the percent transmittance can be recorded from the meter. In the lab, multiple homogeneous solutions are made. There was not a way to determine the differences in concentrations, but the Spec 20 made it possible to measure the difference. The Beer-Lambert Law is a graph used to record
The wavelength was set to absorbance of 600 nm, which is the max for Cu2+. Ten small test tubes were cleaned and a piece of label tape was placed around the top of each tube. A vertical straight line was drawn on the tape to help align with the mark on the instrument sample holder. The transmittance of the Spec 20 was set to 0% using the left-hand adjustment knob while the well was empty and closed. One test tube was filled 3/4 full of a blank solution (distilled water). A Kimwipe was used to wipe off any solution on the outside of the test tube. The test tube was then placed into the empty well with both the mark on the test tube and the mark on the well aligned. The lid of the well was closed. The right-hand adjustment knob was used for setting the transmittance to
Once recorded, it was possible to find the absorbance of the solution by using the equation: A=2-log(%T). The Beer-Lambert Law was used to provide a calibration plot on the relationship between absorbance and concentration. From Figure 1, the calibration curve shows the absorbance vs. concentration of the standard solutions of Cu2+. Figure 2 shows absorbance vs. concentration of concentrations made. The solutions in figure two were found my using the formula MC * VC = MD * VD. Concentration of molarity and volume were given from previous information in the lab. Dilution of molarity was also used from previous information form the lab. Dilution of volume was found using basic algebra. The VD plus water must equal 20 mL to create each made solution. Concentration is defined as molarity. It is found by dividing the number of moles of solute by the volume of solution in liters. Absorbance is defined as the amount of wavelengths taken in by the