Chemical Reactions And Equations Class 10 Notes Pdf Download

[Fritzi Schlicker]

(iii) Change in state of substance: The combustion reaction of candle wax is characterised by a change in state from solid to liquid and gas (because the wax is a solid, water formed by the combustion of wax is a liquid at room temperature whereas, carbon dioxide produced by the combustion of wax is a gas). There are some chemical reactions which can show more than one characteristics.

chemical reactions and equations class 10 notes pdf download

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Explain that in most chemical reactions, two or more substances, called reactants, interact to create different substances called products. Tell students that burning a candle is an example of a chemical reaction.

Note: Explain to students that chemical reactions are more complicated than the simplified model shown in the animation. The animation shows that bonds between atoms in the reactants are broken, and that atoms rearrange and form new bonds to make the products.

In reality, the reactants need to collide and interact with each other in order for their bonds to break and rearrange. Also, the animation shows all of the atoms in the reactants coming apart and rearranging to form the products. But in many chemical reactions, only some bonds are broken, and groups of atoms stay together as the reactants form the products.

A chemical reaction is a process in which reactants are converted into products. Chemical equations are used to illustrate chemical reactions. In a chemical reaction, the conversion of reactants into products results in some observable features known as characteristics of chemical reactions. The important characteristics are the Evolution of a gas, formation of a precipitate, Change in colour, Change in temperature and Change in the state. Anyone of these general characteristics can tell us whether a reaction had taken place or not.

Chemical reactions are important in a variety of businesses, cultures, and even our daily lives. They are always occurring in our environment, such as rusting of iron, pottery, and wine fermentation, to name a few. A chemical change must occur in a chemical reaction, which is commonly observed with physical changes such as precipitation, heat generation, colour change, and so on.

In a chemical reaction, the transformation of reactants into products is frequently accompanied by specific characteristics that may be seen. Chemical reactions have a number of significant properties like:

Students have difficulty distinguishing between physical and chemical change, despite formal teaching, and the distinction is somewhat arbitrary. However an understanding of the differences between purely physical processes such as melting, evaporation and boiling and the changes that take place in chemical reactions, particularly the idea that new substances are formed, is important to an understanding of chemistry and students very frequently confuse the two. The following conversations are typical:

Research shows that students frequently use the term chemical change to describe changes in physical state. Freezing and boiling are considered to be examples of chemical reactions. This depends on their conception of substance. If students regard ice as a different substance from liquid water they are likely to classify the melting of ice as a chemical change. One study found that 80% of students considered a difference in colour between the reactant and product evidence of chemical change. Students can consider potassium permanganate (Condy's crystals) dissolving in water to be a chemical change because of the intense difference in colour. Melting and expansion on heating were also considered to be evidence of chemical change by some students.

When teaching about physical and chemical changes it is important to allow students to see the classification as a continuum. They should be able to observe a number of changes and formulate their views on the kind of change and problems with the classification process. Students should come to see that chemical reactions produce new chemicals distinct from the starting materials but that chemical processes can be reversed. Examining examples of reversible chemical reactions and considering why it is difficult to reverse many chemical changes can be very useful.

Practise using and build the perceived usefulness of a scientific model or idea
It is important that examples of changes are not confined to only the materials and chemicals students are exposed to in the classroom. As a homework activity students could be asked to collect examples of changes they see around them and classify these on their scale of physical and chemical changes. Some examples they may collect are combustion of fuels, cooking and processes such as digestion, respiration and photosynthesis.

Clarify and consolidate ideas for/by communication to and with others
To consolidate their views students in groups could be asked to choose two changes, one which is on the physical end of the continuum and one on the chemical end and explain to the class what the differences are. Communicating their ideas to others can help students clarify and consolidate new and existing ideas about changes.

Challenge some existing ideas
Although it is difficult to demonstrate the reversibility of chemical changes, students are very familiar with the need to recharge their mobile phones, cameras and other rechargeable devices. This could be simply discussed, although investigating the chemical reactions that power these devices could be a useful research project. A caveat here is that much of the available information can be very technical.

Equation Challenge Game - An updated version of the Snowman Challenge Game, which includes new questions in addition to the equations from the original challenge for a total of 60 problems. I printed out the challenge cards and placed each one inside an Easter egg, which I hid in various locations around my classroom. I have the kids work in pairs to find problems and solve them. Rules and directions are printed on the top of the student worksheet.

My students have difficulty identify the different types of chemical reactions. I use this worksheet after we have already discussed balancing equations to explore the differences between synthesis, decomposition, single replacement, and double replacement reactions. Students watch a movie about chemical reactions and then use colored pencils to help them determine what happens during the reaction. Teacher notes have been provided along with the student worksheet and answer key.

Gibbs Free Energy is used to measure the amount of available energy that a chemical reaction provides. As reactions are usually temperature dependent, and sometimes work significantly better at some temperatures than others, the ΔGf values known are only valid at 25C (298.15 K).

In this investigation, students classify chemical reactions as exothermic or endothermic. Next, students explore the relationship between an observed change in temperature and the classification of a change as chemical or physical.

After students explore one example of an endothermic change and one example of an exothermic change, they are then asked to explore the connection between energy changes and chemical reactions. To do this, students may need some guidance to arrive at the idea that temperature changes may also accompany dissolving.

This investigation introduces the concepts of enthalpy (heat) of ΔH in the context of exothermic and endothermic reactions. To give students a deeper grounding in the basics and reinforce basic concepts covered previously, you may wish to review the mechanics of chemical changes, how to write balanced chemical equations, and the law of conservation of energy.

In this investigation, you will observe whether energy is absorbed or released in two different chemical reactions and categorize them as exothermic and endothermic. You will also explore the relationship between energy changes and chemical reactions.

Some of the scientists of the 18th and 19th centuries carried out fundamental experiments on chemical reactions. They proved from their experiments that during chemical reactions composition of the matter changes and that change remains permanent. On the contrary, during physical change, only the state of matter changes and this change is often temporary in nature. Identify physical and chemical changes from the phenomena given in the following table.

A physical change takes place due to change in the parameters such as temperature, pressure. Often a physical change in reversible. The composition of matter remains the same in a physical change. For example, ice is transformed into water on heating and water is transformed into ice on cooling. On the contrary, if the composition of matter changes during a process then it is called a chemical change. When we call a particular process or phenomenon as a chemical change, some chemical reactions are taking place in the concerned matter.

In this way, a balanced equation is obtained from an unbalanced equation by applying proper factors to the appropriate reactant/product to balance the number of each element in steps. We saw that in chemical reactions reactants get converted into new substances called products. During this, some chemical bonds in the reactants break and some new chemical bonds are formed to transform the reactants into the products. In this chapter, we will be studying the types of reactions in detail.

Class 10 Science Chapter 1 Notes of Chemical Reactions and Equations for the preparation of exams. 10 Science Chemistry Chapter 1 notes are in such a way that it covers the entire chapter clearing the concepts of Chemical Reactions, Equations involves and types of reactions with examples. These are prepared for the academic session 2023-24 CBSE Exams based on latest CBSE Syllabus 2023-24. Contents according to need may be added during the session, if required.

According to the Elements of Chemical Reaction Engineering manual, yield refers to the amount of a specific product formed per mole of reactant consumed.[3] In chemistry, mole is used to describe quantities of reactants and products in chemical reactions.

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