Lesson 1 - Matter in Our Surroundings

-

 Matter in Our Surroundings

Matter

  • Matter is anything that has mass and occupies space.
  • Everything that we can touch, see, hear, taste and also smell is matter.
  • Matter is made up of tiny particles which cannot be seen through the eye.
The particles of which the matter is comprised, influence its state and properties (physical and chemical).

Characteristics of Particles of Matter 

1. Particles of matter are very small

Particles of matter are tiny atoms or molecules, too small to see without a microscope—a single gram holds trillions of them. 

For example, a few crystals of potassium permanganate color a whole bucket of water because the particles spread out easily. 

This shows matter is made of these minuscule, mobile building blocks.

2. Particles of matter have spaces between them

This characteristic provides the solubility of a substance in other substances.

For example, on dissolving sugar in water, there is no rise in water level because the particles of sugar get into the interparticle spaces between the water particles.

3. Particles of matter are always in motion

Particles of the matter show continuous random movements due to the kinetic energy they possess.

A rise in temperature increases the kinetic energy of the particles, making them move more vigorously.

4. Particles of matter attract each other

In every substance, there is an interparticle force of attraction acting between the particles. 

To break a substance, we need to overcome this force. The strength of the force differs from one substance to another.

States of Matter

• Matter can be classified on the basis of interparticle forces and the arrangement of particles:
  • Solid
  • Liquid 
  • Gas
  • Plasma
  • BEC (Bose-Einstein-Condensate) 

• These three forms of matter are interconvertible by increasing or decreasing pressure and temperature. 

For example, ice can be converted from solid to a liquid by increasing the temperature.

(A) Solid

  • Fixed shape and volume
  • Strong intermolecular force
  • Particles are tightly packed
  • Cannot be compressed
  • Do not flow
Examples: Ice, wood, stone

(B) Liquid

  • Fixed volume but no fixed shape
  • Takes shape of container
  • Particles less tightly packed
  • Can flow
  • Slightly compressible
Examples: Water, milk, oil

(C) Gas

  • No fixed shape or volume
  • Fill entire container
  • Very weak intermolecular force
  • Highly compressible
  • Particles move very fast
Examples: Air, oxygen, carbon dioxide

(D) Plasma

The state consists of super energetic and super excited particles. These particles are in the form of ionised gases. 
The fluorescent tube and neon sign bulbs consist of plasma.

(E) Bose - Einstein Condensate

Indian physicist Satyendra Nath Bose made a study regarding the fifth state of matter.
Based on his study, Albert Einstein predicted a fifth state of matter called the Bose-Einstein Condensate. 
The Bose-Einstein Condensate or BEC is formed by cooling a gas of extremely
low density to super low temperatures

Physical Nature of Matter

  • A physical property is that aspect of the matter that can be observed or measured without changing its nature or composition.
  • It is independent of the amount of matter present.
  • Physical properties include appearance, colour, odour, density, texture, melting point, boiling point, solubility, etc.

Diffusion

When the particles of matter intermix on their own with each other, the phenomenon is called diffusion. 
For example, spreading of ink in water.

  • During diffusion, the particles occupy the interparticle spaces.
  • The rate of diffusion increases with increase in the temperature, due to increase in kinetic energy of the particles.

Examples of diffusion in gases:

• The aroma of food being cooked in the kitchen reaches us even from a considerable distance due to diffusion.

• The fragrance of a burning incense stick spreads all around due to diffusion.

• The fragrance of a perfume spreads due to the diffusion of the perfume particles into air.

Examples of diffusion in liquids:

• Colour of potassium permanganate is acquired by water, on its own, due to the diffusion of potassium permanganate particles in water.

• The spreading of ink in water, on its own, is due to the diffusion of ink particles in the water.

Examples of diffusion in solids:

• If two metal blocks are bound together tightly and kept undisturbed for a few years, then the particles of one metal are found to have diffused into the other metal.

• If we write something on a blackboard and leave it undisturbed for atleast 10 to 15 days, we will find that it becomes quite difficult to clean the blackboard afterwards. This is due to the fact that some of the particles of chalk have diffused into the surface of the blackboard.

Brownian Motion 

Random, erratic, and zigzag motion of particles suspended in a fluid (liquid or gas) results from their bombardment by the fast moving atoms or molecules of the fluid (liquid or gas). This haphazard motion of the particles is known as brownian Motion.

Effect of change of temperature on state of matter

On increasing temperature, the kinetic energy of the particles of the matter increases and they begin to vibrate with a higher energy. Therefore, the interparticle force of attraction between the particles reduces and particles get detached from their position and begin to move freely.
  • As a result, the state of matter begins to change.
  • Solids undergo a phase change to form liquids.
  • Similarly, liquids also undergo a phase change to form gases.

Melting point

The melting point of a solid is defined as the temperature at which solid melts to become liquid at the atmospheric pressure.
  • At melting point, these two phases, i.e., solid and liquid are in equilibrium, i.e., at this point both solid state and liquid state exist simultaneously.
  • Melting point is the characteristic property of a substance. For example, melting point of ice is 0°C (273 K).

Boiling point

The temperature at which a liquid starts boiling, at atmospheric pressure, is called its
boiling point.
  • Boiling is a bulk phenomenon.
  • At the boiling point, the vapour pressure of the liquid is equal to the atmospheric pressure.
  • For example, boiling point of water is 100°C. (Or 100°C = 273 + 100 = 373K)

Freezing point (Liquid → Solid)

The temperature at which the state of a substance changes from a liquid to a solid is called the freezing point of that substance.

Effect of Change of Pressure

  • Gases can be liquefied by applying pressure and reducing the temperature.
  • When a high pressure is applied to a gas, it gets compressed and if the temperature is lowered, the gas is liquefied.

Change of State of Matter (Phase transition)

Interconversion of States of Matter

The phenomenon of change from one state of matter to another, and then back to the
original state is called the interconversion of states of matter.


Change of state is affected by changes in condition such as:
i. Changes in temperature 
ii. Increasing or decreasing pressure 
iii. Changes in both, temperature and pressure 

Melting (Solid → Liquid)

The process, in which a solid turns into a liquid at a specific temperature is called melting.
Ice melts at 0° C.

Condensation (Gas → Liquid)

The process, in which a gas, on cooling, turns into a liquid at a specific temperature is called condensation or liquefaction.
  • Formation of clouds is due to the condensation of water vapour from the Earth’s surface.
  • The heat removed from the surface through evaporation is released into the atmosphere by the formation of clouds. This process cools the Earth’s climate.

Vapourisation (Liquid → Gas)

The process of conversion of a substance from the liquid state to the gaseous state at a fixed temperature (boiling point), is called vapourisation.

Water vapours at 100°C.

Sublimation (Solid → Gas)

The transition of a substance directly from its solid phase to gaseous phase without changing into the liquid phase (or vice versa) is called sublimation.
Examples:- Camphor, Naphthalene, Ammonium Chloride, Solid carbon dioxide and Iodine.

Evaporation (Liquid → Gas)

The process of conversion of a substance from the liquid state to the gaseous state at any temperature below its boiling point is called evaporation or vapourisation.
Evaporation is a surface phenomenon.

Factors Affecting Evaporation

• Temperature: The rate of evaporation increases with an increase in temperature.
• Surface area: The rate of evaporation increases with an increase in surface area.
• Humidity: The rate of evaporation decreases with an increase in humidity.
• Wind speed: The rate of evaporation increases with an increase in wind speed.

Cooling due to evaporation

During evaporation, the particles of a liquid absorb energy from the surroundings to overcome
the inter-particle forces of attraction and undergo the phase change. The absorption of heat from
the surrounding makes the surrounding cool.
For example, sweating cools down our body.

Difference between Evaporation and Boiling

Evaporation

  • It is a surface phenomenon.
  • It is a slow process.
  • It takes place at all temperatures but below the boiling point.

Boiling

  • It is a bulk phenomenon.
  • It is a rapid process.
  • It takes place at a definite and constant temperature.

Latent heat

The hidden heat which breaks the force of attraction between the molecules is
known as the latent heat. Since, the heat energy is hidden in the bulk of the matter, it is called latent heat.

Latent heat of fusion

The heat energy required to convert 1 kilogram of a solid into liquid at
atmospheric pressure, at its melting point, is known as the latent heat of fusion.
• When we supply heat energy to water, the particles start moving faster.
• At a certain temperature, a point is reached when the particles have enough energy
to break free from the forces of attraction of each other.
• At this temperature, the liquid starts changing into a gas.

Latent heat of vaporisation

It is the amount of heat energy that is required to change 1 kg of a liquid into gas at atmospheric pressure at its boiling point.

Latent heat of condensation 

It is the amount of heat energy that is required to change 1 kg of a gas into liquid at atmospheric pressure at its boiling point.

Latent heat of solidification 

It is the amount of heat energy that is required to change 1 kg of a liquid into solid at atmospheric pressure at its freezing point.





Comments

Post a Comment

Popular posts from this blog

Lesson 3 - धातु और अधातु-Class 10 Science Notes

-
Image
 धातु और अधातु धातु धातु वे तत्व हैं जो ऊष्मा और विद्युत् का संचालन करते हैं और लचीले और तार खींचने योग्य होते हैं। उदाहरण:- आयरन (Fe), एल्युमिनियम (Al), सिल्वर (Ag), कॉपर (Cu), गोल्ड (Au), प्लेटिनम (Pt), सोडियम (Na), पोटैशियम (K), कैल्शियम (Ca), लेड ( Pb), मैग्नीशियम (Mg), लिथियम (Li) आदि। धातु वे तत्व हैं जो इलेक्ट्रॉनों का त्यागकर धनात्मक आयन बनाते हैं। इस प्रकार धातुओं को विद्युत धनात्मक तत्व के रूप में जाना जाता है। धातुओं के भौतिक गुण 1. धातुएँ कठोर और चमकदार होती हैं। अधिकांश धातुएँ कठोर होती हैं, क्षार धातुओं को छोड़कर, जैसे सोडियम, पोटेशियम, लिथियम आदि बहुत नरम धातुएँ होती हैं। इन्हें चाकू से काटा जा सकता है। 2. धातुएँ प्रबल और तन्य होती हैं। अधिकांश धातुएं मजबूत होती हैं और इनमें उच्च तन्यता शक्ति होती है। इस वजह से, तांबे (Cu) और आयरन (Fe) जैसी धातुओं का उपयोग करके बड़ी संरचनाएं बनाई जाती हैं। सोडियम (Na) और पोटेशियम (K) को छोड़कर जो नर्म धातु हैं। 3. धातुएँ ठोस होती हैं।  पारा (Hg) को छोड़कर धातु कमरे के तापमान पर ठोस होती है, जो कमरे के तापमान पर तरल होती है। 4. ध...
Read more

Lesson 10 - प्रकाश- परावर्तन तथा अपवर्तन - Class 10 Science Notes

-
Image
 प्रकाश- परावर्तन तथा अपवर्तन प्रकाश :- प्रकाश ऊर्जा का एक रूप है जो हमें अपने आस-पास की चीजों को देखने में सक्षम बनाता है। प्रकाश एक स्रोत से प्रारंभ होता है और उन वस्तुओं से परावर्तित होता है जिन्हें हमारी आंखों से देखा जाता है और हमारा मस्तिष्क इस संकेत को संसाधित करता है, जो अंततः हमें देखने में सक्षम बनाता है। कुछ सामान्य घटनाएं:- प्रकाश से जुड़ी कुछ सामान्य अद्भुत घटनाएं होती हैं जैसे दर्पणों द्वारा प्रतिबिम्ब बनना, तारों का टिमटिमाना, इंद्रधनुष के सुंदर रंग, माध्यम द्वारा प्रकाश का मुड़ना। प्रकाश की प्रकृति:- प्रकाश निम्न की भाति व्यवहार करता है- किरण (जैसे परावर्तन और अपवर्तन) तरंग (जैसे व्यतिकरण और विवर्तन) कण (जैसे फोटोइलेक्ट्रिक प्रभाव) प्रकाश के गुण:- प्रकाश एक विद्युत चुम्बकीय तरंग है, इसलिए इसे यात्रा करने के लिए किसी माध्यम की आवश्यकता नहीं होती है। प्रकाश सीधी रेखा में गमन करता है। प्रकाश की दोहरी प्रकृति होती है अर्थात तरंग भी और कण भी। प्रकाश छाया उत्पन्न करता है। निर्वात में प्रकाश की गति अधिकतम होती है। इसका मान 3 × 10 8  मीटर/सेकंड होता है। जब प्रकाश किसी ...
Read more

Lesson 2 - अम्ल, क्षार और लवण-Class 10 Science Notes

-
Image
 अम्ल, क्षार और लवण संसूचक संसूचक वे पदार्थ हैं जो रंग परिवर्तन द्वारा विलयन की अम्लीय या क्षारीय प्रकृति को दर्शाते हैं संसूचक के प्रकार संसूचक कई प्रकार के होते हैं- 1. प्राकृतिक संसूचक प्राकृतिक स्रोतों से प्राप्त संसूचक प्राकृतिक संसूचक कहलाते हैं। उदाहरण- लिटमस, हल्दी, लाल पत्ता गोभी, चीनी गुलाब आदि। लिटमस :- लिटमस लाइकेन से प्राप्त होता है। लिटमस का विलयन बैंगनी रंग का होता है। लिटमस पेपर दो रंगों में आता है- नीला और लाल। * अम्ल नीले लिटमस पत्र को लाल कर देता है। * क्षार लाल लिटमस पत्र को नीला कर देता है। हल्दी:- हल्दी एक प्राकृतिक संसूचक है। हल्दी पीले रंग की होती है। हल्दी का विलयन या हल्दी का पत्र क्षार के साथ लाल भूरे रंग का हो जाता है। हल्दी अम्ल के साथ रंग नहीं बदलती है। 2. घ्राण (सूंघनेवाला) संसूचक वे पदार्थ जो अम्ल या क्षार के साथ मिश्रित होने पर अपनी गंध बदलते हैं, घ्राण संसूचक कहलाते हैं। उदाहरण-प्याज, वैनिला आदि। प्याज:- प्याज का पेस्ट या रस क्षार में मिलाने से उसकी महक खत्म हो जाती है। यह अम्ल के साथ अपनी गंध नहीं बदलता है। वेनिला:- वेनिला की गंध क्षार के साथ गायब...
Read more