Chemistry Unit 1 Experiment Solutions HS 2nd year

 

🧪 Experiment 1: Preparation of a Binary Liquid Solution and Determination of Mass Percentage

Objective: To prepare a binary solution of ethanol and water and calculate mass percentage of ethanol.

Materials:

• Ethanol (absolute), distilled water

• Measuring cylinder, digital balance, beaker, stirrer

Procedure:

1. Measure 10 g of ethanol using a digital balance.

2. Add 90 g of water to the ethanol in a beaker.

3. Stir well to form a homogeneous solution.

Observation:

• Total mass = 100 g

• Mass % of ethanol = (10/100) × 100 = 10%

Conclusion: A 10% (w/w) ethanol-water solution was successfully prepared.

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🧪 Experiment 2: Demonstrating Henry’s Law with Carbonated Water

Objective: To demonstrate that gas solubility increases with pressure (Henry’s Law).

Materials:

• Soda water bottle (sealed), 2 beakers, stopwatch

Procedure:

1. Open the soda bottle and immediately pour into a beaker. Record fizzing and bubbles.

2. Compare with soda kept open for 24 hours in another beaker.

Observation:

• Immediate effervescence upon opening.

• Flat soda in open beaker shows reduced dissolved CO₂.

Conclusion: Gas solubility decreases when pressure above the liquid decreases, demonstrating Henry’s Law.

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🧪 Experiment 3: Elevation of Boiling Point

Objective: To compare boiling points of pure water and salt solution.

Materials:

• Distilled water, NaCl, thermometer, beakers, tripod stand, Bunsen burner

Procedure:

1. Boil 100 mL of water and note the boiling point.

2. Dissolve 5 g NaCl in 100 mL of water. Heat and record the new boiling point.

Observation:

• Pure water boils at ~100°C

• Salt solution boils at slightly higher temperature (~101°C)

Conclusion: Addition of non-volatile solute elevates boiling point (colligative property).

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🧪 Experiment 4: Determining Freezing Point Depression

Objective: To observe the effect of a solute (salt) on freezing point of water.

Materials:

• Ice bath, thermometer, salt, water, beakers, stirrer

Procedure:

1. Measure freezing point of distilled water (~0°C).

2. Add salt to water, stir, place in ice bath.

3. Measure freezing point again.

Observation:

• Salt solution freezes at a temperature below 0°C.

Conclusion: Presence of solute lowers the freezing point of solvent.

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🧪 Experiment 5: Demonstrating Osmosis Using a Potato Osmoscope

Objective: To observe osmosis through a biological membrane.

Materials:

• Raw potato, sugar solution, distilled water, knife, beaker

Procedure:

1. Cut potato to create a cavity and place sugar solution inside.

2. Place the potato in a beaker containing distilled water.

3. Observe after 30 minutes.

Observation:

• Water enters potato cavity, raising the liquid level.

Conclusion: Water moves from lower solute concentration (distilled water) to higher (sugar solution) – osmosis.