Science Buddies: "Ask an Expert"

Please my son needs help answering the question at the end of the experiment ,he didn't understand everything from the teacher because he was rushing and my son has trouble hearing good and I really don't understand this stuff
The questions starts with which ink component where the most polar for each brand ?least polar and how did you know
2. how did the separation order differ for each solvent system, marker brand and solid phase? Why?
3. how did the R factor values differ for each solvent system, marker brand and solid phase? why?
4. which combination of solid phase and solvent separated out each brand of marker the best?
Thank you please I need answers by Monday morning if not even before because it due Monday and I signed up with this amazing website before but I had trouble activating my account
Thanks in advance

Hello bahia89,

I'm sorry to hear that you are having trouble with these questions. I hope this reply is not too late.

First, the black ink should have separated into different colors during the chromatography experiment. I'll assume that is what your son observed when I help clarify how to answer these questions. I will actually answer them in a different order than they are listed, because I think it is easier to answer the first question after answering questions 2, 3, and 4.

Question 2: To answer this question, take a look at the chromatography papers. The dyes may have ended up in different orders in different experiments. The test with water, for example, may have the dyes in a different order than the test with alcohol. As a made-up example, let's say the black marker separated into cyan, magenta and yellow. In one test, they might have ended up in the order (starting at the top of the paper and moving down) magenta, cyan, yellow. But, in another test perhaps the order was yellow, magenta, and cyan. The distance that a dye moves up the chromatography paper depends on whether the dye molecule bonds more strongly with the paper or the solvent. If the molecule likes to bond with the paper, it won't move very far up the paper. But, if the molecule prefers the solvent, then it will move up much farther. As a result, the order of the dyes may be different when different solvents are used.

Question 3: Figure 1 in the background section of the Project Idea shows how to measure Rf. To answer this question, I would make a table with dye colors in the rows (one row for each color the black ink separated into) and the solvents (water, alcohol, nail polish remover) as columns. Write the appropriate Rf values in each cell of the table, and determine if the Rf values for a given dye are different in different solvents. You should make a different table for each marker you tested. The Rf factor is related to how far the dye moves up the paper versus how far the solvent moves up the paper. It is another way of helping you figure out whether the dye molecule prefers bonding with the molecules in the paper or the molecules in the solvent. A big Rf means that the dye molecule "likes" the solvent molecules and moves easily with them. A smaller Rf means the dye molecule "likes" the molecules in the paper more. The bigger the Rf value, the more the dye molecule prefers bonding with the solvent.

Question 4: To answer this question, look at the data tables from question 3 and determine which one has the largest spread in Rf values. If, for example, the Rf values of marker A on paper in water were 0.75, 0.5, and 0.25 and the Rf values for Marker B on paper in alcohol were 0.9, 0.5, and 0.2, then the combination Marker B on paper in alcohol did a better job separating the dyes than Marker A on paper in water.

Question 1: Water is a polar molecule, while alcohol is not. If the dye is a polar molecule, it will prefer bonding with the water and will move up the chromatography paper farther when water is the solvent. If the dye is a non-polar molecule, it will prefer bonding with the alcohol over the water and that dye will move farther up the paper when alcohol is the solvent. The most polar dye is the dye will move farthest up the paper when water is the solvent; the least polar dye will move farthest up the paper when alcohol is the solvent.

Let me know if I can clarify something or help you in another way. I will get an email if you post a reply and get back to you within a day of your post.