explain how will you liquefy gases with the help of activity
Answers
1.1.2 HOW SMALL ARE THESE PARTICLES OF MATTER?
Activity ______________ 1.2
Take 2-3 crystals of potassium permanganate and dissolve them in 100 mL of water.
Take out approximately 10 mL of this solution and put it into 90 mL of clear water.
Take out 10 mL of this solution and put it into another 90 mL of clear water.
Keep diluting the solution like this 5 to 8 times.
Is the water still coloured ?
NCERT Class IX Science Chapter 1 Matter in Our Surroundings
This experiment shows that just a few crystals of potassium permanganate can colour a large volume of water (about 1000 L). So we conclude that there must be millions of tiny particles in just one crystal of potassium permanganate, which keep on dividing themselves into smaller and smaller particles. Ultimately a stage is reached when the particles cannot divide further into smaller particles.
The same activity can be done using 2 mL of Dettol instead of potassium permanganate. The smell can be detected even on repeated dilution.
The particles of matter are very small – they are small beyond our imagination!!!!
1.2 Characteristics of Particles of Matter
1.2.1 PARTICLES OF MATTER HAVE SPACE BETWEEN THEM
In activities 1.1 and 1.2 we saw that particles of sugar, salt, Dettol, or potassium permanganate got evenly distributed in water. Similarly, when we make tea, coffee or lemonade (nimbu paani ), particles of one type of matter get into the spaces between particles of the other. This shows that there is enough space between particles of matter.
1.2.2 PARTICLES OF MATTER ARE CONTINUOUSLY MOVING
Activity ______________ 1.3
Put an unlit incense stick in a corner of your class. How close do you have to go near it so as to get its smell?
Now light the incense stick. What happens? Do you get the smell sitting at a distance?
Record your observations.
Activity ______________ 1.4
Take two glasses/beakers filled with water.
Put a drop of blue or red ink slowly and carefully along the sides of the first beaker and honey in the same way in the second beaker.
Leave them undisturbed in your house or in a corner in the class.
Record your observations. What do you observe immediately after adding the ink drop?
What do you observe immediately after adding a drop of honey?
How many hours or days does it take for the colour of ink to spread evenly throughout the water?
Activity ______________ 1.5
Drop a crystal of copper sulphate or potassium permanganate into a glass of hot water and another containing cold water. Do not stir the solution. Allow the crystals to settle at the bottom.
What do you observe just above the solid crystal in the glass?
What happens as time passes?
What does this suggest about the particles of solid and liquid?
Does the rate of mixing change with temperature? Why and how?
From the above three activities (1.3, 1.4 and 1.5), we can conclude the following:
Particles of matter are continuously moving, that is, they possess what we call the kinetic energy. As the temperature rises, particles move faster. So, we can say that with increase in temperature the kinetic energy of the particles also increases.
In the above three activities we observe that particles of matter intermix on their own with each other. They do so by getting into the spaces between the particles. This intermixing of particles of two different types of matter on their own is called diffusion. We also observe that on heating, diffusion becomes faster. Why does this happen?