Unknown Mixtures Lab Report
Purpose: Unknown mixtures will be separated by means of chromatography in which the mixture will be passed in a solution through a medium leaving behind components of the mixture at different rates, therefore, different spots on the absorbing substance. This will help determine the identity of unknown mixtures. The spot colors on the strip of filter paper and the Rf values of the unknown samples will be compared to those of known samples. To find the position of the spots on the strip of paper, we will use the Retention factor equation:
Rf = D/L= (distance component moves)/(distance solvent moves)
Procedure: From the laboratory textbook Chemical Principles by Slowinski, Wolsey, and Rossi (p. 7-10, chapter 2), our experiment began. First,
an unknown mixture and a piece of filter paper (19cm long and 11cm wide) were obtained. The paper was marked every 2cm and labeled with the formulas for the known and unknown mixtures. The following solutions were put in separate test tubes about 2-3 drops of 0.1M solution each:
AgNO3 Co(NO3)2 Cu(NO3)2 Fe(NO3)3 Bi(NO3)3
Next, we put 2 drops of each of the five solutions into a single test tube. It was mixed well. An applicator was dipped into one of the cation solutions and put in the correct area on the premade, labeled filter paper. The applicator was cleaned and the step was repeated until all known and unknown solutions were on the filter paper. The filter paper was dried and applications of the various solutions were reapplied to the filter paper in their intended regions. Again, the paper was dried.
About 15mL of eluting solution was poured into a 600-mL beaker and covered with a watch glass. The filter paper was taped into a cylinder shape and placed in the 600-mL beaker and covered. The effect of the staining reagent was tested on the different cations. After 75min, the filter paper was removed from the beaker and dried. Cations were noted. The staining reagent was then sprayed on the filter paper. Distance L and distance D were measured. The Rf values were calculated for each known and unknown cation and then compared.
Waste Disposal Note: The eluting solution was poured into the proper waste container.
Rf = D/L= (distance component moves)/(distance solvent moves)
Procedure: From the laboratory textbook Chemical Principles by Slowinski, Wolsey, and Rossi (p. 7-10, chapter 2), our experiment began. First,
an unknown mixture and a piece of filter paper (19cm long and 11cm wide) were obtained. The paper was marked every 2cm and labeled with the formulas for the known and unknown mixtures. The following solutions were put in separate test tubes about 2-3 drops of 0.1M solution each:
AgNO3 Co(NO3)2 Cu(NO3)2 Fe(NO3)3 Bi(NO3)3
Next, we put 2 drops of each of the five solutions into a single test tube. It was mixed well. An applicator was dipped into one of the cation solutions and put in the correct area on the premade, labeled filter paper. The applicator was cleaned and the step was repeated until all known and unknown solutions were on the filter paper. The filter paper was dried and applications of the various solutions were reapplied to the filter paper in their intended regions. Again, the paper was dried.
About 15mL of eluting solution was poured into a 600-mL beaker and covered with a watch glass. The filter paper was taped into a cylinder shape and placed in the 600-mL beaker and covered. The effect of the staining reagent was tested on the different cations. After 75min, the filter paper was removed from the beaker and dried. Cations were noted. The staining reagent was then sprayed on the filter paper. Distance L and distance D were measured. The Rf values were calculated for each known and unknown cation and then compared.
Waste Disposal Note: The eluting solution was poured into the proper waste container.