QUALITATIVE TESTS FOR ELEMENTS IN COMPOUNDS
•
Test #1
- Mix thoroughly 4g of CuO and 2g of glucose in a dry ignition tube. Clamp the tube to
an iron stand and fit a cork with bent glass into it.
- Place 3mL of clear limewater into a test tube and immerse the open end of the bent
tube into it. Heat the mixture in the ignition tube and bubble the gas into the
limewater for a few minutes.
• What is formed in the limewater?
• What is the chemical composition of the precipitate?
• The presence of what element in glucose does it prove?
• Examine the upper end of the ignition tube. What can be observed?
• What other elements are present in glucose?
• Test #2
A. Prepare four dry test tubes as follows:
- Tube 1 with 1ml of acetone
- Tube 2 with 1ml benzene
- Tube 3 with 1ml of ethanol
- Tube 4 with 1 ml of kerosene
B. Put a piece of ferrox paper into each tube and observe the color change in the solution
after shaking.
- Result: ___________________________
• Test #3
- Place a pinch of urea in a small amount of soda lime in a dry test tube and heat over a
small flame. Waft the smoke towards your nose and note the odor of the fumes.
Expose moist red and blue litmus paper to the fumes and note the color change on the
papers.
• How do you describe the odor of the fumes?
• What is the reaction of the fumes with the litmus?
• What gas evolved in the reaction?
• What element is proved present in urea?
• Test #4-1
- Heat a copper wire on a Bunsen flame until only an orange color is imparted on the
flame. Cool the wire and dip in chloroform. Reheat the wire and observe the color
imparted on the flame.
• What is the color imparted on the flame?
• Test #4-2
- Acidify 1ml of chloroform by adding 1-2 drops of 5% NH3 and boil gently for a few
minutes. Cool and add drops of 1% AgNO3 solution. Note the precipitate formed.
• What is the color of the precipitate?
• What is its composition?
• What element is proven to be present in the two tests of #4?
• Test #5
- Add 5 drops of 10% NaOH to egg albumin solution (5%) in a test tube; add two drops
of 5% lead acetate solution. Boil over water bath and observe the precipitate formed.
• What is the color of the precipitate?
• What is its composition?
• What element is present in the egg albumin proven in the test?
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