Complete Chemistry Textbook Grade 9 - Pakistan 2022-2023 PDF

# Model Textbook of CHEMISTRY - Grade 9 ## Based on National Curriculum of Pakistan 2022-23 ### Preface In a historic footstep, the national curriculum of Pakistan 2022-2023 has introduced a new era for schooling in the country. This is the first-ever core curriculum in the 75-year history of Paki...

# Model Textbook of CHEMISTRY - Grade 9 ## Based on National Curriculum of Pakistan 2022-23 ### Preface In a historic footstep, the national curriculum of Pakistan 2022-2023 has introduced a new era for schooling in the country. This is the first-ever core curriculum in the 75-year history of Pakistan. It is in line with the protected right to school education by Article 25-A. Chemistry might be a difficult subject for someone, but it holds significance for those who embrace a systematic approach to understanding its concepts. This new Textbook has been developed as a model Textbook for Pakistan. The book consolidates critical thinking methodologies, guiding scientific reasoning, and thinking abilities. The book incorporates problem-solving strategies, which will guide students toward analytical thinking and skills. These skills would be invaluable for both academic as well as practical life. The book also inspires concept assessment exercises in every unit, which have been designed to evaluate acquired knowledge and promote critical thinking and analyzing data.. One of the book's distinctive features is the key points at the end of each unit, which serve as a quick reference to reinforce the salient features of each unit. ### Contents | Chapter No | Chapter Name | Page No. | |---|---|---| | 1 | Nature of Science in Chemistry | 05 | | 2 | Matter | 15 | | 3 | Atomic Structure | 27 | | 4 | Periodic Table and Periodicity of Properties | 45 | | 5 | Chemical Bonding | 73 | | 6 | Stoichiometery | 96 | | 7 | Electrochemistry | 114 | | 8 | Energetics | 129 | | 9 | Chemical Equilibrium | 137 | | 10 | Acids, Bases, and Salts | 143 | | 11 | Environmental Chemistry-Air | 153 | | 12 | Environmental Chemistry-Water | 166 | | 13 | Organic Chemistry | 177 | | 14 | Hydrocarbons | 195 | | 15 | Biochemistry | 200 | | 16 | Empirical Data Collection and Analysis | 213 | | 17 | Separation Techniques | 227 | | 18 | Qualitative Analysis | 237 | | 19 | Chromatography | 244 | | | Acknowledgment | 248 | | | Glossary | 254 | ## UNIT 01 - Nature of Science in Chemistry ### Student Learning Outcomes (SLOs) - Define chemistry as the study of matter, its properties, composition, and its interactions with other matter and energy. - Explain with examples that chemistry has many sub-fields and interdisciplinary fields. - Formulate examples of essential questions that are important for the branch of chemistry. - Differentiate between 'science' 'technology' and 'engineering' by referring to examples from the physical sciences. ### 1.1 Definition of Chemistry and its Interaction with other Matter and Energy Chemistry is defined as the science that investigates the materials of the universe and the changes that these materials undergo. Chemistry deals with the composition, structure, properties, behavior, and changes of matter and energy. Understanding the fundamental concepts of chemistry help to explain natural phenomena and apply them to the formation of new substances, drugs, and technologies. **Do you know?** - How green chemistry is helpful in understanding and reducing pollution? - Green Chemistry is the model of chemical products and processes that reduce the use of hazardous substances. ### 1.2 Branches of Chemistry Chemistry is a diverse field of study, surrounding numerous sub-fields and interdisciplinary areas. 1. **Organic Chemistry** - Organic chemistry is a branch of chemistry that deals with substances containing carbon (except carbonates, bicarbonates, oxides, and carbides). 2. **Inorganic Chemistry** - Inorganic chemistry is a branch of chemistry that deals with elements and their compounds except organic compounds. 3. **Physical Chemistry** - Physical chemistry is the branch of chemistry that deals with laws and theories to understand the structure and changes of matter. 4. **Analytical Chemistry** - Analytical chemistry is a branch of chemistry that deals with the methods and instruments for determining the composition and properties of matter. 5. **Biochemistry** - The branch of chemistry that deals with physical and chemical changes that occur in living organisms is called biochemistry. 6. **Environmental Chemistry** - Environmental chemistry is the branch of chemistry that deals with the study of chemical and toxic substances that pollute the environment and their adverse effects on human beings. 7. **Industrial Chemistry** - Industrial chemistry is the branch of chemistry that deals with the large-scale production of chemical substances. 8. **Medicinal Chemistry** - The branch of chemistry deals with the study of the interaction between drugs and biological targets, as well as the development of new medicinal agents. 9. **Polymer Chemistry** - The branch of chemistry that focuses on the study of polymers, their types, properties, uses, importance, and types of polymerizations is called polymer chemistry. Examples of synthetic polymers include nylon bearings, plastic bags, polyethylene cups, polyester, Teflon coated cook ware, and epoxy glue etc. 10. **Geochemistry** - Geochemistry is the branch of chemistry that deals with the study of chemical composition, distribution, and transformation of elements and compounds in the Earth's crust, such as rocks, minerals, soils, water, and the atmosphere. 11. **Nuclear Chemistry** - The branch of chemistry that deals with the changes that occur in atomic nuclei is called nuclear chemistry. 12. **Astrochemistry** - Astrochemistry is a branch of chemistry that deals with the study of chemical processes and reactions that occur in astronomical environments, such as stars, planets, comets, and interstellar space. ### 1.3 Examples of Essential Questions that are Important for the Branches of Chemistry Some essential questions for various branches of chemistry that can help enhance understanding are as follows: **Physical Chemistry** - What is the structure of an atom, and how does it influence chemical behavior? - How do different types of chemical bonds (ionic, covalent, metallic) form and function? **Organic Chemistry** - Why carbon is considered the backbone of organic compounds? - What are the major functional groups in organic molecules, and how do they affect chemical properties? **Inorganic Chemistry** - What distinguishes inorganic compounds from organic compounds? - How does Periodic table helps to organise elements? **Analytical Chemistry** - How are analytical methods used to identify and quantify chemical substances? **Biochemistry** - How do biomolecules such as carbohydrates, proteins, nucleic acids, and lipids contribute to the structure and function of living organisms? **Environmental Chemistry** - How do human activities contribute to air pollution, and what are the consequences for the environment? - What role do greenhouse gases play in climate change, and how can we mitigate their effects? **Medicinal Chemistry** - How are drugs designed and developed for specific therapeutic purposes? **Polymer Chemistry** - What are polymers, and how do their structures affect their properties? **Geochemistry** - How do geological processes influence the distribution of elements in the Earth's crust? **Nuclear Chemistry** - How do nuclear reactions differ from chemical reactions, and what are their applications? - What is the role of radioisotopes in medicine and industry? **Astronomy** - What types of reactions occur in astronomical environments? These questions can serve as a foundation for exploring the key concepts within each branch of chemistry. ### 1.4 Daily Life Applications of Chemistry **Organic Chemistry** To treat diseases, organic chemists synthesize new medicines that interact with specific targets like proteins or enzymes. **Inorganic Chemistry** Lithium-ion (Li-ion) batteries are used as rechargeable batteries for electronics, toys, wireless headphones, handheld power tools, small and large appliances, electrical storage devices, and electric vehicles. **Analytical Chemistry** Forensic chemistry is the application of analytical chemistry. It involves the examination of physical traces, such as body fluids, bones, fibers and drugs. It can be used to identify an unknown compound. For example drugs are often found in various colored powders and are analyzed to determine their content. **Physical Chemistry** Physical chemistry is a part of our everyday life. The batteries in our vehicles are built on the principle of electrochemistry. **Environmental Chemistry** Environmental chemistry is used to protect water that has been poisoned by soil, and dust by using different methods e.g., sedimentation, filtration, and disinfection. ### 1.5 Science', 'Technology' and 'Engineering' **Science** Science is the systematic process of constructing and organizing knowledge about the universe. Thus, science seeks to understand the natural world. For example, chemists seek to understand the behaviour and properties of materials, chemical reactions, and the fundamental principles that control the behaviour of matter. **Technology** Technology is the process of applying scientific knowledge to practical applications, resulting in the creation of tools, machines, and systems that enhance our lives. Science and technology play a major role in the field of chemistry by providing tools, machines, techniques and methods which can help in discovery and, development of new materials. These also help in improving quality of products. Technology has revolutionized the field of chemistry, making research and applications more efficient. It has enabled chemists to more effectively analyze and identify substances. Their work is beneficial for chemists working in pharmaceutical and other chemical industries. **Engineering** Engineering is the use of science and mathematics to design and construct systems, structures, and tools for various processes. Chemical engineers develop and design manufacturing processes for the production of chemicals, fuels, food, medicines, polymers, detergents, paper etc. They often work to maximize productivity and product quality. ### 1.6 Applications of Science and Technology and Engineering Let's take a look at how science, technology and engineering work together to solve problems in real-world situations. For example: **Example 1.1: Investigating rusting of Iron.** Imagine trying to figure out why a bike or car will rust over time. Scientists could investigate the chemical reactions that occur between iron, water and oxygen that cause rust to form. Experiments could be conducted to understand the factors that influence this process and help develop strategies to prevent rust. **Example 1.2: Harnessing Solar Energy** Scientists may study the principles of photovoltaic cells to understand how sunlight can be converted into electricity. Technologists can develop solar panels based on the scientific principles discovered. Engineers play their role in designing and implementing large-scale renewable energy systems. For instance, an electrical engineer might design the wiring and connections of a solar power plant, a civil engineer could be involved in designing the infrastructure. In this example, science helps us understand the underlying principles of converting sunlight into electricity. Technology transforms this knowledge into practical applications, such as solar panels and energy storage systems. Engineering takes these technologies and implements them on a larger scale. Together, science, technology, and engineering contribute to the development and utilization of sustainable energy sources. **Example 1.3: Designing a Water Filtration System** let's look at how engineers design water filtration systems. Chemical engineers can help develop processes to remove contaminants from water while mechanical engineers design physical components. Together, they create a solution to clean drinking water for a community. From understanding chemical reactions to using technological devices to solving practical problems through engeneering. **Example 1.4: Organic Chemistry in Action** How do you make french fries. The oil used to fry potatoes contains carbohydrates, which are organic molecules. Scientists study carbohydrates to learn more about how they work, so food technologists extract oil from seeds. Chemical engineers design oil production equipment and processes so that oil is produced efficiently and safely for cooking. **Example 1.5: Plastic Bags** Think about the science behind plastic bags. Scientists study the small building blocks known as monomers. When monomers combine, they form long chains known as polymers. One of those long chains is polyethylene, which is one of the many polymers found in plastic bags! Engineers and technicians use these discoveries to create bags that are durable, flexible, and easy to make. These examples demonstrate how science, technology, and engineering work together in various aspects of our daily lives. Whether it's understanding chemical reactions, using technological devices, or solving practical problems through engineering solutions, these concepts are interconnected and contribute to advancements that impact the world around us. ### Key Points - Chemistry is the study of matter around us. - The branch of chemistry deals with carbon compounds (except bicarbonates, carbonate oxides, and carbides). - The branch of chemistry that deals with the elements and their compounds except organic compounds is called inorganic chemistry. - Industrial chemistry is concerned with the large-scale production of chemical substances. - The branch of chemistry that deals with the laws and theories to understand the structure and changes of matter is called physical chemistry. - Science is defined as the study of nature. - Technology is the application of science. ### Review Questions 1. Encircle the correct answer. (1) Which branch of chemistry is the study of elements and their compounds except for organic compounds? (a) Physical Chemistry (b) Organic Chemistry (c) Inorganic Chemistry (d) Geochemistry Chemistry (ii) Which branch of chemistry helps to protect water that has been poisoned by soil? (a) Environmental Chemistry (b) Organic Chemistry (c) Inorganic Chemistry (d) Geochemistry Chemistry (iii) Which area of Chemistry improves to gauge the behavior of pollutants and develop techniques for pollution control? (a) Analytical Chemistry (b) Organic Chemistry (c) Environmental Chemistry (d) Geochemistry (iv) The branch of chemistry that helps to treat diseases, organic and to synthesize new medicines. (a) Physical Chemistry (b) Organic Chemistry (c) Inorganic Chemistry (d) Environmental (v) The branch of science helps to understand chemical products and processes that reduce the use of hazardous substances: (a) Analytical Chemistry (b) Physical chemistry (c) Green Chemistry (d) astrochemistry (vi) To identify the concentration of a particular solution through titration is and application of (a) Astrochemistry (b) Analytical Chemistry (c) Geochemistry (d) Organic chemistry (vii) The batteries in our vehicles are built on the principle of electrochemistry. It is the application of: (a) Astrochemistry (b) Analytical Chemistry (c) Organic chemistry (d) Physical chemistry (viii) The branch of chemistry that is concerned with the large-scale production of chemical substances is: (a) Industrial chemistry (b) Physical chemistry (c) Inorganic chemistry (d) Environmental Chemistry (ix) The branch of chemistry that focuses on the study of polymers, their types, properties, uses is called: (a) Industrial Chemistry (b) Polymer chemistry (c) Organic Chemistry (d) astrochemistry (x) The study of the interaction between drugs and biological targets, as well as the development of new medicinal agents. (a) Organic chemistry (b) Medicinal chemistry (c) Inorganic chemistry (d) Environmental Chemistry 2. Give short answer. (i) How does chemistry help a doctor to know about the chemical nature of medicine? (ii) In what ways does technological innovation help to understand the development of new materials? (iii) Differentiate between geochemistry and astrochemistry. (iv) With the help of an example correlated the use of science, technology, and engineering. (v) With the help of the Venn diagram compare and contrast organic and inorganic chemistry. (vi) What are the uses of nuclear chemistry? 3. Define chemistry and its interactions with other matter and energy. 4. Describe the applications of inorganic chemistry and its importance in our daily lives? 5. With the help of few examples highlight the relation between science, technology and engineering. 6. Evaluate the role of chemistry in environmental science. 7. How does geochemistry help us to solve the problems such as pollution and climate change? 8. How is organic chemistry applied in medicines, biochemistry and industrial science? ### Project - Draw figure of a tree showing different branches of chemistry. - Composting is a great way to recycle materials that might be thrown into landfill. It takes years to decompose them. Make an indoor composter and determine how readily different materials decompose. ## UNIT 02 - Matter ### Student Learning Outcomes (SLOs) - Define matter as a substance having mass and occupying space. - State the distinguishing macroscopic properties of commonly observed states of solids, liquids, and gases in particular density, compressibility and fluidity. - Identify that state is a distinct form of matter (examples could include familiarity with plasma, intermediate states and exotic states e.g. BEC or liquid crystals). - Explain the allotropic forms of solids (some examples may include diamond, graphite, and fullerenes). - Explain the differences between elements, compounds, and mixtures. - Identify solutions, colloids and suspensions as mixtures and give an example of each. - Explain the effect of temperature on solubility and formation of unsaturated and saturated solutions ### Introduction The study of chemistry revolves around the study of matter which is all around us; not only is the entire world made up of matter but so are we, so are the objects that we use. From this we can derive the definition of matter: Anything that has mass and occupies space is called matter. This makes air, water, rocks, and even people are examples of matter. Different types of matter can be described by their mass. Matter is itself composed of the atom. The atom is the building block of all matter and it is the various combinations of these atoms that make up all the matter that we see around us. You may ask yourself how the book you are reading and the water you are drinking are both matter. They neither look nor feel nothing alike. So how can they both fall into the definition of matter? From there we reach the conclusion that there are states of matter which differ from each other in the way that the atoms that make them up are arranged: ### 2.1 State of Matter There are four states of matter 1. Gas 2. Liquid 3. Solid 4. Plasma Each state is a distinct form of matter. 1. States of matter are the different forms in which matter can exist. These are solids, liquids, gases, and plasmas. These states are determined by the arrangement and movement of particles and the strength of intermolecular and atomic forces. 2. Energy can change matter into different states. For example, solids become liquids or gases when heated. At very high temperatures or when subjected to a strong electric field, the gas transforms into plasma. Under normal conduction, most substances remain in one distinct state: solid, liquid, or gas. Temperatures and energy levels on the Earth are not sufficient to ionize atoms and create plasma. 3. When heated, some crystalline solids turn into cloudy liquids that completely dissolve. This cloudy state is called liquid crystal. Liquid crystal states have many properties of liquids and some properties of solids. This form exists within a certain temperature range. When heated further, the state of the liquid crystal changes to a transparent liquid. 4. Furthermore, there are other states such as Bose-Einstien Condensates(BEC) which is defined as the state of matter in which separate atoms cooled to temperatures very close to absolute zero. BEC is observable under extreme conditions of cold temperature. Superfliud and superconductors are the two main materials which contain BEC. ### 2.2 Elements, Compounds and Mixtures Matter can be described with both physical properties and chemical properties. Matter can be classified as: 1. **Pure substance** - Element - Compound 2. **Mixture** - Homogeneous - Heterogeneous mixtures are - Colloid - Suspension Earlier, we talked about the atom and how atoms make up all of matter. Same types of atoms are called elements. An element consists of atoms that have the same atomic number also known as the proton number. This is the simplest form of matter which cannot be broken down through chemical means. While a physical change alters the physical properties of a substance, a chemical change forms a new substance completely. **Element:** the simplest form of matter made up of the same type of atoms So we have learnt that matter is made up of atoms and the atoms that have the same proton number are called elements. The combination of these different elements makes up the diversity of objects we see around us. When two or more elements chemically combine, meaning undergo a chemical reaction to form a new substance, this is called a compound. As this is a completely new substance, it is completely different from the elements that were used to make it. **Compound:** A substance formed when two or more different atoms chemically combine. Mixtures are the physical combinations of substances. A mixture that does not contain the same types of particles. If you were to examine the chemical composition of the particles in a mixture, the particles would be chemically different from each other. Tea is an example of a mixture. Tea is made up of milk, water, tea leaves and sugar all of which have different chemical compositions. **Mixture:** It is a substance formed when two or more substances physically combine. ### 2.3 Allotropes The property of an element to exist in different physical forms is called allotropy. These different forms in the same physical state are called allotropes. They are different structural forms of the same element. For example, Diamond, graphite and buckyballs are three important allotropes of carbon. **Graphite:** Graphite is composed of flat two dimensional layers of hexagonally arranged carbon atoms. In a layer, each C-atom is covalently bonded to three other Carbon atoms. Weak intermolecular bonds exist between each layer which allows the layers to slide over one another without breaking the bonds. This arrangement makes graphite soft and slippery, making it ideal to be used as a lubricant. Graphite is a good conductor of electricity. **Diamond:** Diamond is the hardest and the purest crystalline allotrope of carbon. In its structure, each C-atom is covalently bonded to four other carbon atoms forming a rigid network of tetrahedral shape. This tetrahedral, three-dimensional arrangement makes it the hardest substance with a very high melting point. Since all the Carbon atoms are bonded with other carbon atoms, no free electrons are present resulting in the structure being non-conductive. Diamond is non-conductor of electricity. **Buckyballs (C-60):** Buckyballs, also known as fullerenes, have a football like fused hollow ring structure made up of twenty hexagons and twelve pentagons. Each of its 60 carbon atoms are bonded to 3 carbon atoms. ### 2.4 Solution A solution is a homogeneous mixture of two or more substances in which one substance is dissolved in the other. Homogeneous means that no particles or parts of different substances can be seen. When one substance dissolves, the solution looks exactly the same. A substance that is dissolved is called a solute and a substance in which it is dissolved is called a solvent. In solution, the particles are microscopic, less than 1 nm in diameter. A solution is a very stable mixture and the solute does not separate from the solvent itself. In salt solution, salt is the solute and water is solvent. More than one solute may be present in a solution. For example, in soft drinks, water is a solvent while other substances like sugar, salts and CO₂ are solutes. Consider the example of air where Nitrogen gas is solvent and Oxygen, carbon dioxide and trace gases are solute. On the basis of physical states of solvent and solute can be categorized as solid, liquid and gaseous solutions. Generally, solutions are found in three physical states depending upon the physical state of the solvent, e.g. air is a gaseous, sea water is a liquid solution and alloy is a solid solution in real life. **Gaseous Solutions** In Gaseous Solutions solvent is a gas and solute can be a gas or liquid or solid. For example a mixture of nitrogen and hydrogen used in Haber's process (ammonia formation) and other is mixture of ammonia and carbon dioxide used for urea preparation. Fog, clouds and mist are examples of solutions where liquid water (solute) is dissolved in air (solvent). Smoke is a solution of carbon particle in gaseous air in our daily life. **Liquid Solutions** Carbonated drinks are solutions where solvent is liquid water and solute is gaseous carbon dioxide. Rectified spirit produced by fermentation of sugar cane, Vinegar (acetic acid in water), are examples of solutions where liquid dissolved in liquid. Brine and sugar syrup are solutions of solid salt and sugar in water. **Solid Solutions** Hydrogen gas on the nickel metal surface is used in ghee industry where hydrogen gas is solute and nickel catalyst is solvent. Solution of any metal (solid) in liquid mercury is called amalgam. Alloy industry is very common these days. Alloys are formed by mixing different metal (Brass, Bronze, steel). ### 2.4.1 Aqueous Solutions Aqueous solution is formed by dissolving a substance in water. The dissolved substances in an aqueous solution may be solids, gases, or other liquids. In order to be a true solution, a mixture must be stable. For example, sugar in water and table salt in water. Water is called a universal solvent because it dissolves majority of compounds present in earth's crust. Aqueous solutions are mostly used in the laboratories. ### 2.4.2 Saturated Solution A solution containing maximum amount of solute at a given temperature is called saturated solution. When a small amount of solute at given temperature is added in a solvent, solute dissolves very easily in the solvent. If the addition of solute is kept on, a stage is reached when solvent cannot dissolve any more solute. At this stage, further added solute remains undissolved and it settles down at the bottom of the container. On the particle level, a saturated solution is the one, in which undissolved solute is in equilibrium with dissolved solute. At this stage, dynamic equilibrium is established. Although dissolution and crystallization continue at a given temperature, but the net amount of dissolved solute remains constant. ### 2.4.3 Unsaturated Solution A solution which contains lesser amount of solute than that which is required to saturate it at a given temperature, is called unsaturated solution. Such solutions have the capacity to dissolve more solute to become a saturated solution. ### 2.4.5 Supersaturated Solution When saturated solutions are heated, they develop further capacity to dissolve more solute. Such solutions contain greater amount of solute than is required to form a saturated solution and they become more concentrated. The solution that is more concentrated than a saturated solution is known as supersaturated solution. Supersaturated solutions are not stable. Therefore, an easy way to get a supersaturated solution is to prepare a saturated solution at high temperature. It is then cooled to o a temperature where excess solute crystallizes out and leaves behind a saturated solution. ### Activity 2.1 Take 100g water in a beaker. Add a tea spoon of sugar in it. Stirr it. The sugar will dissolve. Repeat the process and the and added sugar will again dissolve in it. A solution which can dissolve more of the solute at a given temperature is called an unsaturated solution. Go on adding sugar in the above solution till it starts settling down at the bottom of the beaker at a particular temperature. The solution which cannot dissolve more solute at a particular temperature is called a saturated solution. Now heat the solution, stir it, add more sugar and it will dissolve. Go on adding more sugar and stir it. A stage will reach when no more sugar will dissolve and will start settling down at the bottom of the beaker. This solution is called supersaturated solution. A solution that contains more of the solute than is contained in the saturated solution is called supersaturated solution. How to know whether a solution is saturated or supersaturated? A supersaturated solution is not stable in the presence of crystals of solute. If you add a crystal of sodium thiosulphate to its saturated solution, it will simply drop to the bottom, without dissolving. But if you add a crystal of sodium thiosulphate to a supersaturated solution of sodium thiosulphate (see figure 2.4), crystallization will start. When crystallization has finished, you will have a saturated solution in the presence of sodium thiosulphate crystals. ### 2.4.6 Concentrated and Dilute Solution The solutions are classified as dilute or concentrated on the basis of relative amount of solute present in them. Dilute solutions are those which contain relatively small amount of dissolved solute in the solution. Concentrated solutions are those which contain relatively large amount of dissolved solute in the solution. For example, brine is a concentrated solution of common salt in water. These terms describe the concentration of the solution. Addition of more solvent will dilute the solution and its concentration decreases. ### 2.4.7 Solubility Solubility is the maximum amount of solute which dissolves in a specified amount of solvent at a specific temperature. The solubility of a substance depends on the solvent used, as well as temperature and pressure. See Table 2.2. ### 2.4.8 Effect of Temperature on Solubility The solubility of solutes depends on temperature. Depending on the nature of solute there is either: (a) Increase in solubility with temperature e.g., KCI, NH,CI (b) Decrease in solubility with temperature e.g., Na₂SO, Ca(OH)₂ ### Table 2.2: Solubility of some salts g/100g of solvent at Different Temperatures | (Solute) | Solubility (Amount of solute in 100g of solvent at 20°C | Solubility (Amount of solute in 100g of solvent at 100°C | |---|---|---| | NaCl | 36.5g/100g H₂O | 39.2g/100g H₂O | | KCL | 34.7g/100g H2O | 56g/100g H₂O | | NH₄CL | 37.5g/100g H₂O | 77g/100g H2O | | Ca(OH)₂ | 0.173g/100g H₂O | 0.066g/100g H₂O | **Example:** An example of a solute Whose decreases in solubility with increasing temperature is calcium hydroxide, which can be used to treat chemical burns and as an antacid. ### 2.5 Colloids & Suspensions **Colloid** These are heterogeneous mixtures in which the solute particles are larger than those present in the true solutions but not large enough to be seen by naked eye. A colloid is a mixture that has particles ranging between 1 and 1000 nanometers in diameter, yet are still able to remain evenly distributed throughout the solution. These are also known as colloidal dispersions because the substances remain dispersed and do not settle to the bottom of the container. The particles in such system dissolve and do not settle down for a long time. But particles of colloids are big enough to scatter the beam of light. It is called Tyndall effect. We can see the path of scattered light beam inside the colloidal solution. Tyndall effect is the main characteristic which distinguishes colloids from solutions. Hence, these solutions are called false solutions or colloidal solutions. Examples are starch, albumin, soap solutions, blood, milk, ink, jelly and toothpaste, etc. **Suspension** A suspension is defined as a heterogeneous mixture in which the solid particles are spread throughout the liquid without dissolving in it. It is mixture of undissolved particles in a given medium. Particles are big enough (greater than 1000nm) to be seen with naked eyes. Examples are chalk in water (milky suspension), paints and milk of magnesia (suspension of magnesium oxide in water). For better understanding of true solutions, false solution and suspension, a comparison of their characteristics is given in table 2.3 | S.No | Solution | Colloids | Suspension | |---|---|---|---| | 1 | A homogeneous mixture of two or more components | A heterogeneous mixture of two or more components | A heterogeneous mixture of two or more components | | 2 | Particle size vary from 0.1-1nm. Not visible by naked eye | Particle size vary from 1-10³ nm. Visible by naked eye by naked eye | Particle size greater than 10³ nm. Visible by naked eye by naked eye | | 3 | Particles can pass through normal as well as ultra-filter paper | Particles can pass through normal filter paper but not through ultra-filter paper | Particles cannot pass through normal as well as ultra-filter paper | | 4 | Cannot Scatter the light (due to small size) | Can Scatter the light (Tyndal effect) | Can Scatter the light (Tyndal effect) | | 5 | Does not separate | Does not separate | Separate or settles down when stationary | | Examples | Sea water | Milk | Muddy water | ### Key Points - Anything that has mass and occupies space is called matter. - Plasma is an electrically charged gas, which is affected by electrical and magnetic fields. - The property of an element to exist in different physical forms is called allotropy. - Element: the simplest form of matter made up the same type of atoms - Compound: A substance formed when two or more different atoms chemically combine. - A homogeneous mixture of two or more components is called solution. - Aqueous solution is formed by dissolving a substance in water. - A solution containing maximum amount of solute at a given temperature is called saturated solution. - A solution which contains lesser amount of solute than that which is required to saturate it at a given temperature, is called unsaturated solution - A colloid is a mixture that has particles ranging between 1 and 1000 nanometers in diameter - A suspension is defined as a heterogeneous mixture in which the solid particles are spread throughout the liquid without dissolving in it - References for additional information - Matter and its properties: Joseph Midthun, Paul Kobasa - Cambridge IGSET™ Chemistry 5th Edition - Cambridge International AS & A Level Chemistry (9701) ### Review Questions 1. Encircle the correct answer. (1) Anything that has mass and occupies space is called. (a) Liquid (b) Gas (c) solid (d) Matter (ii) Following are states of matter (a) Gas (b) Liquid (c) Solid (d) All of these (iii) Macroscopic properties are properties that can be visualized by (a) the naked eye (b) microscope (c) electron microscope (d) telescope (iv) Matter can be described by both its (a) physical properties and chemical properties. (b) physical properties (c) chemical properties. (v) A substance formed when two or more different combine chemically. (a) atom (b) compound (c) element (d) solution 2. Give short answer. (1) Can you write the formula of the carbon dioxide gas that we exhale? (ii) Define the element, Compound, Mixture (iii) Differentiate between compound and mixture (iv) Define the term Allotropes Explain the allotropes of Carbon (v) What is difference between Homogeneous and heterogeneous solution? (vi) What are the uses of nuclear chemistry? 3. Define chemistry and its interactions with other matter and energy. 4. Describe the applications of inorganic chemistry and its importance in our daily lives? 5. With the help of few examples highlight the relation between science, technology and engineering. 6. Evaluate the role of chemistry in environmental science. 7. How does geochemistry help us to solve the problems such as pollution and climate change? 8. How is organic chemistry applied in medicines, biochemistry and industrial science? ### Project - Draw figure of a tree showing different branches of chemistry. - Composting is a great way to recycle materials that might be thrown into landfill. It takes years to decompose them. Make an indoor composter and determine how readily different materials decompose. ## UNIT 03 - Atomic Structure ### Student Learning Outcomes (SLOs) - Explain the structure of the atom as the central nucleus containing neutrons and protons surrounded by electrons in shells. - State that, orbits(shells) are energy levels of electrons and a larger shell implies higher energy and greater average distance from nucleus. - State the electrons are quantum particles with probabilistic paths whose exact paths and location cannot be mapped (with reference to uncertainty principle) - Explain that nucleus is made up of protons and neutrons held together by strong nuclear force. - Explain that an atomic model is an aid to understand the structure of an atom. - State the relative charge and relative masses of a subatomic particles (an electron, proton, and neutron). - Interpret the relationship between a subatomic particle, their mass, and charge. - Illustrate the path that positively and negatively charged particles would take under the influence of a uniform electric field. - Define proton number/atomic number as the number of protons in the nucleus of an atom. - Explain that the proton number is unique to each element and use to arrange elements in periodic table. - State that radioactivity can change the proton number and alter an atom's identity. - Define nucleon number/atomic mass as sum of protons and neutrons in the nucleus of an atom. - Define isotopes as different atoms of the same element that have same number of protons but different neutrons. - State that Isotopes can affect molecular mass but not chemical properties of an atom. - Determine the number of protons and neutrons of different isotopes. - Define relative atomic mass as the average mass of Isotopes of an element compared of to1/12th the mass of carbon-12 - State that isotopes can exhibit radioactivity. - Discuss the importance of Isotopes using carbon dating and medical imaging as examples. - Describe the formation of positive(cation) and negative(anion) ions from atoms. - Interpret and use the symbols for atoms and ions