level 8 chemistry states of matter _notes and worksheets

La wisdom Teaching material Level 8 Chemistry Unit 6 Notes and worksheets

Topic 6.1 – Particle Theory

Notes :

Scientists use the idea that all matter is made up of particles to explain the properties of solids, liquids and gases. But this could not be said as absolute truth. This is a simplest way for explaining the properties of the states of matter.

Solids

1. Solid particles are arranged in regular rows and columns with the particles touching each other.2. Solid particles are held firmly in place by the forces of attraction. 3. The particles can only vibrate – They can NOT move or change places.

Liquids

1. Liquid particles are arranged so that the particles are touching each other but not in a pattern of rows.2. Liquid particles are held together by WEAKer forces of attraction. 3. The particles can move past each other.

Gases

1. Gaseous particles do not touch each other at all.2. Gaseous particles are have NO forces of attraction for each other. 3. The particles can move freely.

Plasma

1. Hot ionized gas consisting of approximately equal numbers of positively charged ions and negatively charged electrons.

2. Lightning discharges 30,000 amperes at up to 100 million volts, and emits light, radio waves, X-rays and even gamma rays.

3. Plasma temperatures in lightening can approach 53,540 degrees Fahrenheit (Compare that with your body temperature is 98.6 degree Fahrenheit)

Questions:

Q. 1. Explain why a solid expands when it is heated.Q.2. Explain how a liquid in a thermometer changes so that it can be used to measure a temperature.Q.3. Use particle theory to explain why solids and liquids cannot be compressed (smashed into smaller volume).Q.4. Use particle theory to explain why liquids and gases can flow.

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Changing state

1. When a solid is heated – the particles vibrate more, because some of the energy is transferred to the particles.

2. If the particles gain enough energy to escape the strong forces of attraction and start to move past each other, they become liquid. This is called melting.

3. If they gain even more energy and can overpower the weak forces of attraction between liquid particles, they become gas. This is called evaporation/boiling.

But this process is reversible in some cases on cooling down.

4. If the gas particles are cooled down. They lose some energy and stop vibrating and come closer and closer. If they come so close that the particles can move past each other, they turn into liquid. This is called condensing/condensation.

5. If the liquid particles cool down even more and attain a definite structure such as in rows and columns, they turn solid. This is called freezing.

6. There is also a case in which in between step can be skipped. A solid can loosen its particles so quickly that it turns gas before it can turn liquid. This is called Sublimation.

Activities:

Glue little balls or grains of pulses to make a solid and then put them very close together in a box this is liquid and far apart in another box, this is gas. Now make the cards with the names - freezing, melting, evaporation, condensation, sublimation deposition and their definition on back side and ask them to fit them like in the diagram above.

For evaporation/condensation -Boil some water in a beaker and cover with steel plate see the gases becoming liquid under the plate.

For sublimation -Heat ammonium chloride in a test tube.

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Worksheet 6.1 Particle theory.

Q.1. In the boxes draw how solid liquid and gas particles are arranged. Remember all particles should be same size.

Solid Liquid Gas

Q.2. Explain what happens (using particle theory) what happens when ice is heated and melts to form water.

Q.3. When the iron ball in the diagram is heated, it no longer fits in its holder. Explain why?

Q.4 Use the terms below to match the statements below.

Boil, compressed, deposition, condensation, evaporation, freeze, gas, heat, liquid, melting, move, solid, vibrate and Sublimation

a. A state of matter where particles do not touch each other ………..b. When Gas is cooled to form a liquid …..c. Particles in a solid do this …..d. When liquid changes into gas ….e. The particles in a liquids and gases can do this but in solids cannot ….f. The state of matter that can be compressed….g. When gas is super cooled quickly that it becomes solid ….h. When solid is super heated quickly that it becomes a gas ….

Q.5. Explain using particle theory

a. How a liquid changes into a gas.b. How a liquid changes into a solid.c. What happens when steam in a bathroom hits a cold mirror.

Q.6. Explain what is plasma and give examples of plasma.

Q.7 Fill the “?” in your notebooks.

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Solids

Liquid Gas


Topic 6.2 Brownian Motion

Robert brown was a Scottish biologist. In 1827, he watched pollen grains ( The tiny grains invisible to naked eye, produced by flowers)

So what do you think – does this random movement only happen in liquids or does it also happen in gases and solids?

Q.8 Write down your prediction!

As you may recall – Solid particles are bound by strong forces of attraction and are not free to move. They can only vibrate. So this kind of random movement is NOT possible in solids. But gases are really free to move. So you would see this random movement in dust particles in a ray of light.

Topic 6.3 – Diffusion

As we saw in the class that you can smell the agarbatti from a far end of the room after a few mins and if you put red food color in water, it will dissolve and make the whole beaker with water reddish. This process of mixing of smell particles uniformly in the air after some time and the mixing of color particles among the water particles is called diffusion.

Diffusion is what makes your tea sweet or bitter, Strong or light, light brown or dark brown. How is this possible? Think in terms of particle theory and Brownian motion.

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Brown noticed that when pollen grains were put onto a drop of water and seen under a microscope,they were jiggling. Why? He thought may be pollen grains are alive and deciding to swim around in water.

So he put dust particles on a drop of water and saw that those were also moving about. So he concluded that its not the dust or pollen but it’s the water particles that are moving randomly. This is called Brownian Motion.

These small water molecules are hitting the pollen grain and the grain seems to be jiggling and we can call it a random walk.


Worksheet 6.2 Diffusion

See how diffusion happens

Questions:

Q.9 If you leave Hibiscus (Red Color flower) tea bag in a hot water, why does the water become red after a few mins?

Q.10 Why do we use hot water for making tea?

Q.11 Is diffusion faster in gases. Explain why or why not.

Q.12 Aleika smelled smoke. He looked outside and saw where it was coming from. There was a pile of leaves that had caught fire. Explain how was Aleika able to smell smoke from inside her home? (Hint: Use particle theory and diffusion principle to explain this phenomenon)

Q.13 Maitreyee was swimming in a pool. There were little kids playing with paint colors on the side of the pool. One boy accidently spilled a bottle of yellow paint in the pool. After swimming for an hour, she noticed that the pool is becoming yellowish. Why and how this happened?

Topic 6.4 – Investigating diffusion

Let’s take the example of making tea.

Particles from the tea leaves diffuse into the hot water. You can make the tea stronger and darker faster by

1. Leaving the tea leaves a little ________(Longer/ shorter) time in the pot.2. Using _______(more/less) tea leaves.3. Stirring the tea leaves ______(faster/slower).

Group activity:Make groups of 3,4 people and think what are the factors that could affect diffusion. Write down the factors.

Some of the factors that affect diffusion are:

Size of particles, mass of the particles, the state of matter, temperature and pressure.

Write down how would you test the affect of each of these?What would be your Control Variables, Dependent and independent variables.

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Worksheet 6.3 Investigating Diffusion

Q.13 Highlight (circle or shade) your prediction: -

Factors that affect diffusion:-

If I do this ↓ Then→

Rate(Speed) of Diffusion will be ↓

Or ↓

Temperature Heat up the beakers High LowSize of particles Use large particles High LowMass of particles Use very heavy particles High LowState of matter Use

A: Solid particles in liquidB: Liquid particles in liquidC: Gas particles in liquid

Higher than BHigher than CHigher than A and B

LowerLowerLower

Q.14 Experiment to test the effect of these factors on the rate(speed) of diffusion we take three beakers for each of the experiments and use same amount of water.

To check the affect on diffusion because of -

What should I change?(Independent variable)Hint : We see the Effect of this thing so it does not depend on the experiment.

What do I keep the same? (controlled variable)

What will I observe?(Dependent variable)Hint: What happens to this variable depends on the experiment, so what is the affect of something ON THIS?

What will I do?METHOD:

What did I see?Result:

Conclusion Factor is affecting diffusion or not. If yes, then how? Directly or Inversely?

Ex 1 Eg.

Temperature Room temperature -25C or ___Cold water-10C or __Hot water 65 C or __

Water,Beaker,Food Dye

How fast diffusion happens

1.Add 40 ml of water in 3 identical beakers.2. Heat one to 65C, Cool one to 10C and leave one as it is.3. Add EQUAL amount of food color to each of them at the same time.

I saw that diffusion happened almost instantly in hot water and it was taking time in room temperature beaker and did not happen in cold water and

Temperature does affect rate of diffusion

Higher temperature means faster diffusion.

So this is a direct relationship.

Ex 2

Size of particles

Ex 3

Mass of particles

Ex 4

State of matter

A: Solid particles in liquidB: Liquid

Use solid ______Use liquid _______Use Gas

In 40ml waterIn 40 ml waterIn 40ml

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particles in liquidC: Gas particles in liquid

________ water

Topic 6.5 Gas Pressure

Reminder: Particles in a gas

Move freely Move randomly Can hit the particles of the container they are in.

Question: After a few days when you return home from a vacation, you will find your room dirty. Why? Answer: The air particles hit the paint particles on the walls of your room and the paint particles leave the wall and mix with the air. So after a few days, these paint particles settle on the various furniture and floor of the room because of gravity.

Think:

a. Do you think that gas (particles) or liquid particles can cause a soda bottle to break? Explain why or why not?Video Link –(Type in youtube->) POWER PRESSURE WASHER ● vs ● PLASTIC POP BOTTLES

b. What if the bottle was made up of steel or iron? Can gas particles break that?

Question: How are tiny gas particles or liquid particles able to break a plastic bottle in the video? Answer: The gas/liquid particles increase in number and gain so much energy that they start moving faster and away from each other causing the gas or liquid to expand. This outward movement of these particles sometimes exert a strong force on small areas of the bottles (high pressure) so that it breaks! Isn’t it?

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Fun Fact: Pressure is amount of force acting on a definite area. So if you (mass- 40kg) are standing on ground and your feet are covering 12cmX12cm area. You would be putting a large amount of Pressure on the floor. You can do the calculation like this:-

Force = Weight (Mass x10)N = 40x10 N= 400N Area = 144cm2 = 0.0144m2 Pressure = 400N /0.0144 m2 = 27,777.77N/m2 =27,777.77 Pascal (So much !!!) Compare that will air pressure on the ground 1,01,325 Pa. (3.5 times more) And this air pressure is also acting on your head!!! This is like one elephant standing on your head.

Q.15 . In the First figure (a and b)-a. What is exerting pressure? ____________b. On what? ____________________c. Why is the pressure high in fig.b? ____________________________________________________________________________________d. Draw Force Diagrams in your notebooks.e. Can we say from the diagram that “Less Space = More pressure”? _Yes/No__

https://www.youtube.com/watch?v=ltydNdKq8xk


Q.18 For each sentence, complete the sentence by choosing the right phrase:

Gas pressure is caused when particles a. collide with each other or b. collide with the surfaces around them

Gas pressure increases when particles a. squashed into smaller places or b. allowed to spread out in smaller spaces

Gas Pressure increases when a gas is a. made colder or b. made hotter

Collapsing water experiment

Video Link - Can Crushed by Air Pressure and https://www.youtube.com/watch?v=c5_ho2sc0fc

Since there are more gas particles in first chamber, they are colliding more with each other and with the walls of the container, so the pressure is more in the first chamber. And we can measure this pressure using a barometer. It shows us the amount of

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You can also increase gas pressure/liquid pressure by:-

Increasing temperature. Increasing the number of particles.

Q.16a. If a gas is forced to a small space what happens to the pressure?b. Describe what will happen to a balloon that has been fully inflated and is put into a hot place? Explain your prediction.

Q.17 Write 10 or more examples in daily life where gas pressure or liquid pressure is used. For e.g. In making Roti.

https://www.youtube.com/watch?v=c5_ho2sc0fc

https://www.youtube.com/watch?v=YUrKPFWs-A8


pressure.

Where will it show high pressure? Left chamber or right? __________Why?

We can draw force diagrams to explain this.

Think : How is a balloon inflated? What happens to the particles inside the balloon and what happens to those outside it?

Force diagram in a balloon Force Diagram in a gas bubble.

-------

b. When Milan was at the airport, the gas inside the packet was at the same pressure as the air pressure around it.What does this mean? Write the correct answer in your notebook.

Gas particles inside the packet collided with the gas packet more often than the gas particles outside the packet.

Gas particles inside the packet collided with the gas packet less often than the gas particles outside the packet.

Gas particles inside the packet collided with the gas packet just as often as the gas particles outside the packet.

c. What changed when Milan was in the aeroplane in the sky. Write the correct answer in your notebook.

Gas particles outside the packet collided with it less often than they did at the airport. Gas particles outside the packet collided with it more often than they did at the airport.

d.Use answers from a, b, c to answer why the bag inflated in the sky?

We can even collapse the water bottle by sucking out all the air particles from inside and it will look like this :

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Q. 19. Milan is on an airport, he has a bad of chips. It is full of gas. When he is up in the sky, the air pressure inside the cabin gets less.. The bag of chips inflate(become big)

a. Make force diagrams.


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level 8 chemistry states of matter _notes and worksheets

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