1
Dilutions Introductory Activity
For this activity, you will need the supplies indicated.
Dilution set 1: Food coloring
Supplies per pair
4 empty 15 mL conical tubes
1 15 mL tube of food coloring
1 50 mL tube of water
Procedure:
1. Into one empty 15 mL tube, pour 5 mL of food coloring. Add water
to the same tube to a FINAL volume of 10 mL. This is “dilution 1”.
Set aside.
2. Into a second empty 15 mL tube, pour 5 mL of food coloring. Add
water to the same tube to a FINAL volume of 15 mL (Pour
carefully!). This is “dilution 2”. Set aside.
3. Into a third empty 15 mL tube, pour 2 mL of food coloring. Add
water to the same tube to a FINAL volume of 10 mL. This is
“dilution 3”. Set aside.
4. Into the fourth empty 15 mL tube, pour 1 mL of food coloring. Add
water to the same tube to a FINAL volume of 10 mL. This is
“dilution 4”. Set aside.
Questions:
1. Line up your dilutions in numerical order. Do you see decreasing
color from tubes 1 down to 4?
2. Assuming the answer to question 1 is “yes”, why is the color intensity
decreasing?
3. What dilution did you make for each of the tubes? Fill in the table
below to figure this out (The dilution will be the shaded column)
Dilution
Volume FC*
Total volume
Vol FC/ total vol
1
2
3
4
*FC = food coloring
Dilutions set 2: Simulation with beads
2
Supplies per FOUR people
1 tube of colored beads
1 tube of white beads
2 empty 50 mL tubes
Procedure:
1. Determine the concentration of colored beads:
a. Volume of colored beads in tube:
______________
b. # of colored beads in tube:
______________
c. Concentration (# col. beads / # mL):
______________
2. Into one empty 50 mL tube, pour 15 mL of colored beads Add white
beads to a FINAL volume of 30 mL. Mix well. This is “dilution A”.
Set aside.
3. Into the second empty 50 mL tube, pour 5 mL of colored beads. Add
white beads to a FINAL volume of 25 mL. Mix well. This is
“dilution B”. Set aside.
Questions:
1. Compare Dilution A and Dilution B. What do you notice?
2. Calculate the dilutions made by filling in the following table. The
dilution made will be in the shaded column.
Dilution
A
B
Volume of colored Volume of total
beads
beads
Vol colored/Total
volume
3. Calculate the final concentrations (shaded column) made by filling in
the following table. How do these compare with the original
concentration?
# col. beads
Dilution
# colored beads
Total volume
/total vol.
A
B