Hon Unit 6 Lab Making Soap _oil_ by lanyuehua


									Making Soap and evaluating Soap vs. Detergent


Cooking oil                                NaOH Solution (25% NaOH in water)
Ethanol                                    Saturated NaCl solution
“Hard” water                               Litmus paper
Mazola® cooking oil                        Dish detergent

Safety – goggles and aprons. Be careful with hot oil and with 25% sodium hydroxide. Wash off skin
promptly. Adding liquids to oil when hot may cause foaming and splashing.

Part 1 – Making soap

Measure out all ingredients first. When you have the NaOH, the ethanol, and the NaCl solution ready,
put 15 ml of cooking oil into a 250 ml. beaker. Add 15 ml of NaOH solution and 15 ml of ethanol. Heat on
the hot plate and stir until there are no layers and the soap is a uniform light tan. Towards the end of
the reaction, the soap may foam up – be careful. Have your beaker tongs ready if you need to take the
beaker off. Pour the soap into 300 ml of NaCl solution and stir well – soap should separate out. Strain
through paper towel folded like filter paper in a funnel, rinse with a small amount of cold water and save
the solid soap.

Part 2 – soap vs. detergent

We will compare soap and detergent for acidity or basicity, ability to disperse oil, and ability to clean in
hard water.

Dissolve 1 g of your soap in 50 ml. distilled water. In a separate container, dissolve 1 g of dish detergent
in 50 mL of water. Half-fill three test tubes with each solution (~10 mL). Test one sample of each
solution with litmus paper for acidity or basicity.

Add 5 drops of cooking oil to one pair of tubes and shake – note differences in how well the oil is
dispersed. What do you think this means about the cleaning capability of each?

Using the second pair of tubes, add ~5 mL of “hard” water (containing Ca Cl2) and shake. What
differences do you see? Calcium ions make water “hard”. What cleaning agent would be most effective in
“hard” water?

To the third set of 2 test tubes, add 5 ml of tap water instead of lime water; shake. What do you
conclude about the hardness of our lab water supply?

Write up a lab report summarizing your observations and conclusions. Construct a data table to record
the results of your tests on various soaps and detergents. What would be the best way to lay out such a

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