Experiment Stock Benzoic Acid

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Register to read the introduction…Procedure First, five standard solutions were made using 10-, 20-, 30-, 40-, and 50-mg/L of caffeine. The 10-mL solution was created by mixing 10-mL caffeine standard and 10.0-mL 0.10M HCl and diluting to 100.0-mL. This same procedure was used to make the rest of the solutions. Then 6.0-mL of soda, with the carbon dioxide removed, was placed in a 100-mL volumetric flask along with 10.0-mL 0.10m HCl and diluted. Then, the UV absorbance of the five standards was taken. Water was used in the reference cuvet. The wavelength of the peak absorbance for caffeine was also taken. The spectroscopy machine automatically corrected the absorbance values against the baseline of the water reference. The results were graphed to create an absorbance versus molar concentration calibration curve. Finally, the UV absorption of the soda sample was measured and compared to the caffeine standard calibration curve. This was used to calculate the concentration of caffeine. Results…show more content…
Molarity was found by Molarity of stock solution=(0.200g/L)/(182.18g/mol)=0.00011M Molarity of Standard 1=(〖(M〗_1 V_1))/V_2 (0.0011M*10mL)/100mL=0.00011M The second standard was 0.00022M with an absorbance of 0.517. The third standard was 0.00033M with an absorbance of 0.547. The fourth standard was 0.00044M with an absorbance of 0.561. The fifth standard was 0.00055M with an absorbance of 0.578. This data gave the following calibration curve: To obtain the concentration of caffeine in the soda sample, the absorbance measured was plugged in as y to

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