Chemical Equations: In activity 1, when calcium oxide reacts with water a new substance is formed which is unlike either calcium oxide or water. This description of chemical reactions that took place in activity-1 is quite long. It can be written in shorter form as a word equation.
The word equation of the above reaction is,
Calcium oxide + Water - Calcium hydroxide ......................... (1)
(Reactants) (Products)
The substances which undergo chemical change in the reaction are called reactants and the new substances formed are called products.
A chemical reaction written in a the form of word equation shows the change of reactants to products by an arrow placed between then the reactants, are written on the left side of arrow and the final substances, or products are written on the right side of the arrow. The arrow head point towards the product shows the direction of the reaction.
If there is more than one reactant or product involved in the reaction, they are indicated with a plus (+) sign between them. Describing a chemical reaction using least possible words or symbols is called a chemical equation.
10th Class Chemistry New Syllabus - Chemical Reactions Activities
Activity-1: Take about 1 gm of quick lime (calcium oxide) in a beaker. Add 10 ml of water to this. Touch the beaker with your finger.
1) What do you notice?
Test the nature of solution with litmus paper.
2) What is the nature of the solution?
In the above activity you will notice that, the beaker is hot when you touch it with you finger. The reason is that the calcium oxide (quick lime) reacts with water and releases heat energy. White calcium oxide dissolves in water producing colourless solution. The solution obtained Is a basic solution. This you will find with litmus paper test.
Activity - 2:
Take about 100 ml of water in a beaker and dissolve a small quantity of Sodium sulphate (Na2SO4). Takeabout 100ml of water in another beaker and dissolve a small quantity of Barium chloride (BaCl2), observe the colours of the solutions obtained.
- What is the colour of these solutions?
- Can you name the solutions obtained?
Add the solution that obtained into beaker and observe changes.
- Did you observe any change on mixing these solutions?
Activity - 3:
Take a few zinc granules in a conical flask. Add about 5 ml of dilute hydrochloric acid to the conical flask. Observe the changes in the conical flask.
- What changes did you notice?
Now keep a burning match stick near the mouth of the conical flask.
- What happens to burning match stick?
- Touch the test tube with your fingers. What did you notice?
- Is there any change in temperature?
From the above activities you can conclude that:
1. A change that changes state and colour of substance.
2. A change that release heat energy.
3. A change which forms an insoluble substance as precipitate.
4. A change that liberate a gas.
In our daily life we observe variety of changes taking place around us. In this chapter we study various types of chemical reactions and their symbolic representation.
1) What do you notice?
Test the nature of solution with litmus paper.
2) What is the nature of the solution?
In the above activity you will notice that, the beaker is hot when you touch it with you finger. The reason is that the calcium oxide (quick lime) reacts with water and releases heat energy. White calcium oxide dissolves in water producing colourless solution. The solution obtained Is a basic solution. This you will find with litmus paper test.
Activity - 2:
Take about 100 ml of water in a beaker and dissolve a small quantity of Sodium sulphate (Na2SO4). Takeabout 100ml of water in another beaker and dissolve a small quantity of Barium chloride (BaCl2), observe the colours of the solutions obtained.
- What is the colour of these solutions?
- Can you name the solutions obtained?
Add the solution that obtained into beaker and observe changes.
- Did you observe any change on mixing these solutions?
Activity - 3:
Take a few zinc granules in a conical flask. Add about 5 ml of dilute hydrochloric acid to the conical flask. Observe the changes in the conical flask.
- What changes did you notice?
Now keep a burning match stick near the mouth of the conical flask.
- What happens to burning match stick?
- Touch the test tube with your fingers. What did you notice?
- Is there any change in temperature?
From the above activities you can conclude that:
1. A change that changes state and colour of substance.
2. A change that release heat energy.
3. A change which forms an insoluble substance as precipitate.
4. A change that liberate a gas.
In our daily life we observe variety of changes taking place around us. In this chapter we study various types of chemical reactions and their symbolic representation.
10th Chemistry New Syllabus - Chemical Reactions and Equations
Chapter 1 - Chemical Reactions and Equations
In lower class you have studied about various changes like temporary changes, permanent changes, natural changes and man made changes etc. and categorized them as physical changes and chemical changes. In this chapter we discuss about chemical changes, reactions in these changes and expressing the reactions in symbolic form.
Consider the following events and think about changes and reactions that are taking place during the occurrence of events.
- coal is burnt.
- food gets digested in our body.
- iron nail is exposed to humid atmosphere for a longtime.
- we respire.
- milk is converted into curd.
- water is added to quicklime.
- crackers are burnt.
What changes do you notice?
Are they physical changes or chemical changes?
Are they temporary changes or permanent changes?
In all the above events, the nature of original substance is changed. Whenever new substances are formed with properties completely unlike those of the original substances, we say a chemical change has taken place.
How do we know a chemical reaction has taken place?
Let us perform some activities to know this.
In lower class you have studied about various changes like temporary changes, permanent changes, natural changes and man made changes etc. and categorized them as physical changes and chemical changes. In this chapter we discuss about chemical changes, reactions in these changes and expressing the reactions in symbolic form.
Consider the following events and think about changes and reactions that are taking place during the occurrence of events.
- coal is burnt.
- food gets digested in our body.
- iron nail is exposed to humid atmosphere for a longtime.
- we respire.
- milk is converted into curd.
- water is added to quicklime.
- crackers are burnt.
What changes do you notice?
Are they physical changes or chemical changes?
Are they temporary changes or permanent changes?
In all the above events, the nature of original substance is changed. Whenever new substances are formed with properties completely unlike those of the original substances, we say a chemical change has taken place.
How do we know a chemical reaction has taken place?
Let us perform some activities to know this.
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