Ways to Bring About Changes – Definition, Changes caused by Heating, and Cooling

Ways to Bring About Changes: We can notice a change by the effects it creates. The object or substance that is subject to change may have a change in shape and size, colour, properties, states and position. Also, the length of a pencil decreases with use. The properties of the substance change when it is cooked. When an iron bar is heated, it turns red hot. Then we can see the colour change. When we boil water, it changes from liquid to gas. When we kick a soccer ball, it changes position. As a child grows, his weight and height change. Have you ever thought about the causes of the changes? If not, read the article below to learn more about the different ways they are responsible for the change.

What is a Change?

Change occurs when an object changes in shape, position, size, colour, state, appearance, and composition due to some factor, which may be external or internal. This change may be permanent or temporary.

Changes occurring around us can be classified as:

1. Slow and fast changes
2. Natural and man-made changes
3. Useful and harmful changes
4. Reversible and irreversible changes
5. Periodic and non-periodic changes
6. Controlled and uncontrolled changes

Different Ways to Bring About Changes

We explore many examples of change such as slow and fast change, reversible and irreversible change, desired and undesirable change, physical and chemical change, etc. Let us know how these changes occur. Some of the ways we can make changes are by heating, cooling, applying pressure, and mixing. Let’s look at them in more detail.

A. Changes Caused by Heating and Cooling

Heat is a form of energy. When we heat an object, it is affected in one way or another. Heat affects several things in the following ways:

1. Certain things get hot when heated and cold on cooling: When we heat water, the temperature of the water rises and becomes hotter. Objects get hot when they are heated. If you keep the water in the refrigerator for some time, the temperature of the water will drop and it will cool down. Objects cool on cooling. The heating and cooling process continues even in nature. The days are warm due to the heat of the sun. The night is cool because there is no heat. Land and sea breezes are also caused by the heating and cooling of the land and sea water / sea water.

2. Certain things expand on heating and contract on cooling: Certain things expand when heated and contract when cooled. The increase in size of an object on heating is called expansion. The decrease in size of an object on cooling, is called contraction. There are many materials that expand when heated and contract when cool. For example, metals like iron and aluminum expand when heated and come into contact when cooled. Let’s use the following examples to understand how it works.

I. Fixing an Iron Rim to the Wooden Wheel of the Cart

Thin iron rims surround a wooden wheel of a bullock cart or horse cart. They are fixed as follows:

1. An iron rim is chosen which is slightly smaller than a wooden rim. Then the iron rim is evenly heated so that it expands and becomes larger.
2. As the iron rim has become larger, it can be easily slid over the wooden wheel.
3. To cool the rim of a hot iron, pour cold water over it. The iron rim shrinks when cooled and fits tightly to the wooden circle.

II. Fixing an Iron Blade to a Wooden Handle

A spade has an iron blade attached to its one end to dig the soil. The iron blade has a rim to which a wooden handle is attached. This is fixed by the changes that occur in the cast iron when heated and cooled. It is secured as follows:

1. The ring of the iron blade is slightly smaller than the thickness of the wooden handle that should be attached to it.
2. The iron ring of the blade becomes hot over the fire. It expands and becomes larger when heated.
3. Wooden handle now fits easily into the hot ring.
4. Then pour cold water over the hot ring to cool it down.
5. As the ring cools down, it contracts to fit tightly against the wooden handle.

III. Goldsmith Creating Gold Jewellery

A goldsmith designs and manufactures gold jewellery by melting solid gold. Goldsmith heats gold pieces until they melt. This gold can be used to make jewellery in any shape desired. The gold jewellery can be melted back to gold for redesigning.

3. Some things change their state: We know that heating and cooling can change the state of matter. For example, when heated, the solid form of water that is ice turns to water which is a liquid form of water and the liquid form of water turns to a gaseous form of water that is vapour.  Similarly, when cooled, the vapour turns into water and the water (in the liquid state) turns into ice (in the solid-state).

4. Certain things begin to burn on heating: When a combustible substance such as paper, candle, kerosene, etc., is heated, it starts burning. For example, when we burn paper, it changes into ash.

B. Changes Caused by Pressure

Pressure can cause many kinds of changes. Some important ones are as follows:

1. Change in shape and size: Inflate the balloon, watch the shape and size of the balloon change. Now let the air escape from the balloon. The balloon deflates and changes its shape and size again. Similarly, if you press fluffy solids such as a pillow, a loaf, a ball of wool, or a sponge, their shape will change. When the pressure drops, they return to their original shape.

2. Breaking objects: When pressure is applied to delicate substances such as glass, biscuits, and coal, they break into pieces.

C. Changes Due to Mixing of Two Substances

We can bring about many changes by mixing substances.

For example,

1) Mixing Salt in Water

1. When salt and water mix, the salt dissolves in the water and forms a salt solution.
2. If the salt solution is heated, the water in the salt solution will evaporate as vapour, leaving behind the salt. The water vapor can be chilled or condensed to return the water.
3. Therefore, we can restore water and salt to their original form, which can be mixed again to obtain the same salt solution. Therefore, mixing salt and water is a reversible change. Because salt and water don’t interact, this type of change is also known as a physical change. Most of the physical changes are reversible.

2) Mixing Curd in Warm Milk

1. If you add a small amount of curd to the warm milk, stir it and leave it in a warm place, the milk will turn into curd.
2. It is not possible to restore the original form of the milk, therefore mixing the curd with the warm milk is an irreversible change. Because curd causes a chemical reaction in the milk, transforming it into curd and losing the original properties of the milk, this type of change is also known as a chemical change. Most of the chemical changes are irreversible.

Summary

Change occurs when an object changes in shape, position, size, colour, state, appearance, and composition due to some factors, which may be external or internal. Changes may be slow and fast, periodic and non-periodic, reversible and irreversible, desirable and undesirable. These changes occur in one or another way. Some of the ways we can make changes are by heating, cooling, applying pressure, and mixing.

FAQs on Ways to Bring About Changes

Q.1. What are the different ways to bring about changes?
Ans: The different ways to bring about changes are as follows:
1. Changes caused due to heating and cooling
2. Changes caused due to pressure or force
3. Changes caused due to mixing two substances.

Q.2. What are the three ways to bring a change?
Ans: The three ways to bring change are as follows:
I. Change caused due to temperature
II. Change caused due to pressure or force
III. Change caused due to mixing two substances.

Q.3. What is change?
Ans: Change occurs when an object changes in shape, position, size, colour, state, appearance, and composition due to some factor, which may be external or internal. This change may be permanent or temporary.

Q.4. What is a chemical change? Explain it with the help of an example.
Ans: A change in which one or more new substances with different properties is formed is called a chemical change.
Burning of paper or wood is an example of chemical change: After the paper or wood is burnt, it changes to ash and we cannot get back the original substance paper or wood again.

Q.5. What are classifications of ways to bring about changes?
Ans: The classification of ways to bring change are as follows:
I. Change caused due to temperature
II. Change caused due to pressure or force
III. Change caused due to mixing two substances

Q.6. What is reversible change?
Ans: Reversible change is a temporary change that can be undone or reversed to obtain the original form.

Learn Everything About Chemical Change Here

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