Introduction: The goal of this lab was for students to learn how to use a spectrophotometer to find the absorbance of four known copper (II) sulfate solutions, four copper (II) sulfate solutions that were created by dilution, and one unknown copper (II) sulfate solution. The purpose of this experiment was to help students learn how to use the Spec-20, learn about the relationship between absorbance and concentration known as the Beer- Lambert law and see the relationship between moles, volume and molarity. The serial dilution technique was also used to dilute solutions to a lower concentration. The main goal of this lab was to teach the practical skill of creating solutions at a specific molarity and help them see the relationship between concentration
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After letting the Spec-20 warm up for fifteen minutes, the wavelength was set to 600nm because it is the maximum absorbance for Cu2+ solutions. Ten test tubes were labeled with a small vertical line so they could be aligned with the spectrophotometer. The Spec-20 was set to 0% transmittance using the left knob without a test tube sample in the holder. Then a test tube filled three-fourths of the way full with distilled water was placed into the Spec-20’s test tube well and the pointer was set to 100% transmittance using the right hand knob.
The next step in the lab is to find the absorbance of the standard solutions of copper (II) sulfate. To find the absorbance, the percent transmittance of the 0.500 M, 0.200 M, 0.100 M and the 0.050 M CuSO4 was recorded by placing each sample into the calibrated Spec-20 spectrophotometer. Transmittance was found by dividing percent transmittance by one hundred. The absorbance value was calculated using the equation A=-log(T) and was graphed to create a calibration …show more content…
It was determined, using the serial dilution technique, that 2.5 grams of solid CuSO4 · 5H2O was required to create 20 mL of 0.500 M CuSO4 solution. The 2.5 grams of solid CuSO4 · 5H2O was added to a 100 mL beaker along with 15 mL of distilled water. The mixture was transferred back and forth between the graduated cylinder and the beakers until a homogenous solution was created. Some of the 0.500 M solution was put into a test tube to be used in the Spec-20. It was calculated that 8 mL of the 0.500 M solution was required to be diluted to create 20 mL of 0.200 M solution. Some of the 0.200 M solution was also set aside to be used in the Spec-20. It was then determined that 10 mL of the 0.200 M solution was required to be diluted to create 20 mL of 0.100 M solution. Finally, 10mL of the 0.100 M solution was diluted to create 20 mL of 0.050 M solution. These four solutions of CuSO4 were each put into the Spec-20 well and the percent transmittance was found. The absorption was found using the equation A=2-log(%T). A CuSO4 solution of an unknown concentration was added to a set tube and the percent transmittance was measured in the
After letting the Spec-20 warm up for fifteen minutes, the wavelength was set to 600nm because it is the maximum absorbance for Cu2+ solutions. Ten test tubes were labeled with a small vertical line so they could be aligned with the spectrophotometer. The Spec-20 was set to 0% transmittance using the left knob without a test tube sample in the holder. Then a test tube filled three-fourths of the way full with distilled water was placed into the Spec-20’s test tube well and the pointer was set to 100% transmittance using the right hand knob.
The next step in the lab is to find the absorbance of the standard solutions of copper (II) sulfate. To find the absorbance, the percent transmittance of the 0.500 M, 0.200 M, 0.100 M and the 0.050 M CuSO4 was recorded by placing each sample into the calibrated Spec-20 spectrophotometer. Transmittance was found by dividing percent transmittance by one hundred. The absorbance value was calculated using the equation A=-log(T) and was graphed to create a calibration …show more content…
It was determined, using the serial dilution technique, that 2.5 grams of solid CuSO4 · 5H2O was required to create 20 mL of 0.500 M CuSO4 solution. The 2.5 grams of solid CuSO4 · 5H2O was added to a 100 mL beaker along with 15 mL of distilled water. The mixture was transferred back and forth between the graduated cylinder and the beakers until a homogenous solution was created. Some of the 0.500 M solution was put into a test tube to be used in the Spec-20. It was calculated that 8 mL of the 0.500 M solution was required to be diluted to create 20 mL of 0.200 M solution. Some of the 0.200 M solution was also set aside to be used in the Spec-20. It was then determined that 10 mL of the 0.200 M solution was required to be diluted to create 20 mL of 0.100 M solution. Finally, 10mL of the 0.100 M solution was diluted to create 20 mL of 0.050 M solution. These four solutions of CuSO4 were each put into the Spec-20 well and the percent transmittance was found. The absorption was found using the equation A=2-log(%T). A CuSO4 solution of an unknown concentration was added to a set tube and the percent transmittance was measured in the