Saturday
November 22, 2014

Homework Help: Chemistry

Posted by Herold on Sunday, February 1, 2009 at 11:02am.

--------Materials---------
several black pens of different types
2.0 mL water
2.0 mL rubbing alcohol
2 coffee filters
small glass or paper cup

--------Procedure--------

You may print this procedure out from Adobe if you wish: chrom.pdf

Cut out a rectangular piece of filter paper 2 inches x 3 inches as shown in the picture to the right. Save the leftover parts of the filter paper.

Cut a piece the same size from the second piece of filter paper.

Gather an assortment of black pens. Try to find several different types: water soluble, permanent (Sharpie), felt tipped, roller.

On each of the papers, draw a pencil line 2 cm from one of the short sides of the paper. See the diagram below. Mark an X on the line for each of the pens.

Dot each pen on a separate X several times. See the picture to the left. Give each of your pens a number and then, on the filter paper, number your X's with a pencil. I used five pens in my example; you will want at least three pens. Don't let your marks be too close together, they will run together. Cut a piece of your extra filter paper to put other marks on that did not fit on this paper.

Pour the water into a small glass or paper cup. Place the filter paper into the cup so the end with the dots is closest to the water. Make sure the dots are not in the water!!

Observe the dots as the water is soaked up by the filter paper. Don't let the water reach the top of the paper. Set the paper out to dry.

Prepare the second piece of filter paper the same as the first. Pour the water out of the cup and dry it well. Repeat step 6 using rubbing alcohol in place of the water. **Again, be sure that the dots of ink are not touching the alcohol!!**

Observe the dots as the alcohol is soaked up by the filter paper. Don't let the alcohol reach the top of the paper. Set the paper out to dry.

-------Observations--------

Create a Word document. Copy and paste these into your word document and type in your observations.

Pen 1:

Type— (example: Crayola watercolor)

Results with: Alcohol—

Results with: Water—

Pen 2:

Type—

Results with: Alcohol—

Results with: Water—

Pen 3:

Type—

Results with: Alcohol—

Results with: Water—

Pen 4:

Type—

Results with: Alcohol—

Results with: Water—

Pen 5:

Type—

Results with: Alcohol—

Results with: Water—

-----Analysis-----

1.The ink in a pen is

a)an element

b)a compound

c)a mixture

2.The water used in the experiment is

a)an element

b)a compound

c)a mixture

3.The alcohol used in the experiment is

a)an element

b)a compound

c)a mixture

4.Pick the ink that spread the best in the water. Find the ink that spread the best in the alcohol. Were these inks from the same pen?

5.List the colors you see in each of the spots you picked in number one.

6.Find pen number one on each of the sheets. Compare the colors on each of the sheets when this ink spread out.

7.Why were you directed to make your line and your X's with a pencil?

8.The water is called a solvent because it dissolves substances. The alcohol is also a solvent. Which seemed to dissolve (spread out) the ink more completely?

9.Alcohol and water are chemical compounds (molecules) made up of atoms. From your answer to number 5, does alcohol or water have more attraction to the inks you chose?

10.You are analyzing a lake that has a large amount of pollution. You notice a substance floating on top. You want to know if this is a mixture of substances, or a compound. How would you go about finding out this information?

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