Table of Contents
Activity 1.5: Comparing Diffusion Rates of Potassium Permanganate or Copper Sulfate in Hot and Cold Water
Objective
To demonstrate how temperature affects the rate of diffusion in liquids by comparing how potassium permanganate or copper sulfate dissolves in hot and cold water.
Materials Needed
- Two transparent glasses or beakers.
- Water (one at room temperature and one heated to near boiling).
- Crystals of potassium permanganate or copper sulfate.
Steps to Perform the Activity
- Fill one glass with cold water (room temperature) and the other with hot water.
- Carefully drop one crystal of potassium permanganate or copper sulfate into each glass. Do not stir.
- Observe the spread of color in both glasses over time.
- Record your observations regarding the speed and pattern of diffusion in hot and cold water.
Observations
- In Hot Water: The color spreads quickly, forming a uniform mixture within a short time.
- In Cold Water: The color spreads slowly, and it takes much longer for the crystal to dissolve completely and for the color to spread uniformly.
Also Check – Chapter 1 -MATTER IN OUR SURROUNDINGS -Class 9 – Simplified notes
Concepts Behind the Activity
- Diffusion in Liquids:
Diffusion is the movement of particles from a region of higher concentration (near the crystal) to a region of lower concentration (surrounding water) until a uniform mixture is formed. - Effect of Temperature on Diffusion:
- In hot water, the water molecules have more kinetic energy due to the higher temperature. These molecules move faster, allowing them to collide with and spread the particles of potassium permanganate or copper sulfate quickly.
- In cold water, the water molecules have less kinetic energy, resulting in slower particle movement and slower diffusion.
- Particle Motion and Kinetic Energy:
Temperature directly affects the kinetic energy of the particles. Higher temperatures increase energy, leading to faster diffusion.
Learning Outcomes
- Temperature Affects Diffusion Rates:
Higher temperatures lead to faster diffusion because particles move more rapidly and spread out quicker. - Intermixing in Liquids:
The activity demonstrates that liquids allow the particles of a solute (e.g., potassium permanganate or copper sulfate) to intermix naturally, with temperature being a key factor. - Role of Kinetic Energy:
The increased energy in hot water speeds up the movement of particles, making diffusion faster.
Applications of Temperature-Dependent Diffusion
- Cooking: Dissolving sugar or salt faster in hot liquids.
- Medicine: Dissolving powdered medicine in warm water for quicker effects.
- Environmental Science: Understanding how pollutants spread in warmer or cooler water bodies.
Intext and additional Question Answers on Activity 1.5: Comparing Diffusion Rates of Potassium Permanganate or Copper Sulfate in Hot and Cold Water
Question 1: What do you observe just above the solid crystal in the glass?
A concentrated color forms just above the crystal as it starts dissolving in the water.
Question 2: What happens as time passes?
The color gradually spreads throughout the water, becoming more uniform due to diffusion.
Question 3: Does the rate of mixing change with temperature? Why and how?
Yes, the rate of mixing increases with higher temperatures. This is because heat provides energy to the water and crystal particles, increasing their movement and the speed of diffusion.
Additional Question: How does temperature affect the movement of particles in water?
Higher temperatures increase the kinetic energy of water molecules. This accelerates their movement, leading to faster collisions with the dissolving particles, which speeds up diffusion.
Conclusion
This activity shows that the rate of diffusion in liquids depends on temperature. Potassium permanganate or copper sulfate spreads faster in hot water because of the higher kinetic energy of the water molecules. This illustrates the relationship between temperature, particle motion, and the diffusion process.
