ScienceA Chemistry ISA

Investigating how the Volume of an Emulsifier Affect the Time Taken to Separate

Preparation Questions

What is an emulsion?

  1. Give three examples of emulsions that you come across in everyday life.
  2. What is an emulsifier?
  3. Why is hand cream made of an emulsion rather than oil on its own?
  4. What was the independent variable in this experiment?

Equipment:
Measuring cylinders
Water
Boiling tubes
Vegetable oil
Emulsifier solution
Marker pen
Stopwatch
Boiling tube rack
Ruler

Method:

  1. Place six boiling tubes in a boiling tube rack;
  2. Label the boiling tubes in order: control, 1 cm3, 2 cm3, 3 cm3, 4 cm3, 5 cm3;
  3. Measure out 10 cm3 of  water into each boiling tube
  4. Add 10 cm3 of vegetable oil into each of the boiling tubes.
  5. The first boiling tube is a control. To the second boiling tube add 1 cm3 of the emulsifier solution, and to the third boiling tube add 2 cm3 and so on until the sixth boiling tube has 5 cm3 of the emulsifier solution in it;
  6. With the marker pen draw a line 1 cm below the top of the oil.
  7. Insert the stopper into the first boiling tube and invert 10 times to mix the solutions;
  8. Once you have completed the inverting, start the stop clock and time how long it takes for a 1 cm high layer of oil to form on top of the solution;
  9. Repeat this inverting and timing process with the other five boiling tubes, recording your results as you go along in a table.
  10. Draw a graph of your results.

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Results.
A student carried out the same experiment as you; their graph and results table are shown below. What conclusion can you make from this experiment?


Mustard Powder(g)

Time to Separate (s)

0

50

2

140

4

240

6

330

8

330

10

340

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