To Obtain Black Oxide Of Copper And Study Its Properties. | Grade Xi

Objective

• To obtain black oxide of copper and study its properties.

APPARATUS REQUIRED

• Bunsen burner
• Tripod stand
• Wire gauze
• Porcelain crucible
• Tongs
• Mortar and pestle
• Filter paper
• Funnel
• Test tube
• Test tube holder
• Graduated cylinder
• Dropping pipette
• pH paper
• Safety goggles
• Gloves

Chemical REQUIRED

• Copper wire
• Oxygen gas
• Distilled water
• Litmus paper
• Sulfuric acid (H2SO4)
• Sodium hydroxide (NaOH)

THEORY

• Copper oxide is a compound of copper and oxygen. It is a black powder that is insoluble in water. It is formed when copper is heated in the presence of oxygen. The chemical equation for this reaction is:

2Cu + O2 -> 2CuO

• Copper oxide is a basic oxide. This means that it reacts with acids to form salts and water. The chemical equation for this reaction is:

CuO + 2HCl -> CuCl2 + H2O

• Copper oxide is also a reducing agent. This means that it donates electrons to other compounds. The chemical equation for this reaction is:

CuO + H2 -> Cu + H2O

PROCESS

1. Preparation of Copper Oxide:

2. Cut a piece of copper wire about 10 cm long.

3. Hold the copper wire with a pair of tongs and heat it in the Bunsen burner flame until it turns black.
4. Allow the copper wire to cool.

5. Grind the black copper oxide to a powder using a mortar and pestle.

6. Study of Copper Oxide Properties:

7. Color: Observe the color of copper oxide.

8. Solubility: Add a small amount of copper oxide powder to a test tube containing distilled water. Shake the test tube and observe the solubility of copper oxide.
9. pH: Test the pH of a copper oxide solution using pH paper.
10. Reaction with acid: Add a few drops of sulfuric acid to a test tube containing copper oxide powder. Observe the reaction.
11. Reaction with base: Add a few drops of sodium hydroxide to a test tube containing copper oxide powder. Observe the reaction.
12. Reducing properties: Add a small amount of copper oxide powder to a test tube containing hydrogen gas. Heat the test tube gently and observe the reaction.

OBSERVATIONS

• Color: Copper oxide is a black powder.
• Solubility: Copper oxide is insoluble in water.
• pH: Copper oxide solution is basic.
• Reaction with acid: Copper oxide reacts with acid to form a salt and water. The reaction is exothermic, and the solution turns blue.
• Reaction with base: Copper oxide reacts with base to form a salt and water. The reaction is exothermic, and the solution turns black.
• Reducing properties: Copper oxide reacts with hydrogen gas to form copper and water. The reaction is exothermic, and the copper oxide powder turns red.

OBSERVATION TABLE

Property	Observation
Color	Black powder
Solubility	Insoluble in water
pH	Basic
Reaction with acid	Forms a salt and water, solution turns blue
Reaction with base	Forms a salt and water, solution turns black
Reducing properties	Reacts with hydrogen gas to form copper and water, powder turns red

Calculation

The molar mass of copper oxide is 79.55 g/mol.

The mass of copper oxide used in the experiment is 0.5 g.

The number of moles of copper oxide used in the experiment is:

n = m/M = 0.5 g / 79.55 g/mol = 0.0063 mol

RESULTS

• Copper oxide is a black powder that is insoluble in water.
• Copper oxide solution is basic.
• Copper oxide reacts with acid to form a salt and water.
• Copper oxide reacts with base to form a salt and water.
• Copper oxide has reducing properties.

PRECAUTIONS

• Wear safety goggles and gloves when performing this experiment.
• Do not heat the copper wire in the Bunsen burner flame for too long, as it may melt.
• Allow the copper wire to cool completely before grinding it to a powder.
• Do not add too much copper oxide powder to the test tubes, as it may cause the reactions to be too violent.