Science Concepts and Activities
C hapter 2
IS MATTER AROUND US PURE
How do we judge whether milk, ghee, butter, salt, spices, mineral water or juice that we buy from the market are pure? physical process of evaporation. However, sodium chloride is itself a substance and cannot be separated by physical process into its chemical constituents. Similarly, sugar is a substance because it contains only one kind of pure matter and its composition is the same throughout. Soft drink and soil are not single substances. Whatever the source of a substance may be, it will always have the same characteristic properties. Therefore, we can say that a mixture contains more than one substance.
Fig. 2.1: Some consumable items
Have you ever noticed the word ‘pure’ written on the packs of these consumables? For a common person pure means having no adulteration. But, for a scientist all these things are actually mixtures of different substances and hence not pure. For example, milk is actually a mixture of water, fat, proteins etc. When a scientist says that something is pure, it means that all the constituent particles of that substance are the same in their chemical nature. A pure substance consists of a single type of particles. As we look around, we can see that most of the matter around us exist as mixtures of two or more pure components, for example, sea water, minerals, soil etc. are all mixtures.
2.1.1 TYPES OF MIXTURES
Depending upon the nature of the components that form a mixture, we can have different types of mixtures.
Activity ______________ 2.1
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Let us divide the class into groups A, B, C and D. Group A takes a beaker containing 50 mL of water and one spatula full of copper sulphate powder. Group B takes 50 mL of water and two spatula full of copper sulphate powder in a beaker. Groups C and D can take different amounts of copper sulphate and potassium permanganate or common salt (sodium chloride) and mix the given components to form a mixture. Report the observations on the
IS MATTER AROUND US PURE
How do we judge whether milk, ghee, butter, salt, spices, mineral water or juice that we buy from the market are pure? physical process of evaporation. However, sodium chloride is itself a substance and cannot be separated by physical process into its chemical constituents. Similarly, sugar is a substance because it contains only one kind of pure matter and its composition is the same throughout. Soft drink and soil are not single substances. Whatever the source of a substance may be, it will always have the same characteristic properties. Therefore, we can say that a mixture contains more than one substance.
Fig. 2.1: Some consumable items
Have you ever noticed the word ‘pure’ written on the packs of these consumables? For a common person pure means having no adulteration. But, for a scientist all these things are actually mixtures of different substances and hence not pure. For example, milk is actually a mixture of water, fat, proteins etc. When a scientist says that something is pure, it means that all the constituent particles of that substance are the same in their chemical nature. A pure substance consists of a single type of particles. As we look around, we can see that most of the matter around us exist as mixtures of two or more pure components, for example, sea water, minerals, soil etc. are all mixtures.
2.1.1 TYPES OF MIXTURES
Depending upon the nature of the components that form a mixture, we can have different types of mixtures.
Activity ______________ 2.1
• •
Let us divide the class into groups A, B, C and D. Group A takes a beaker containing 50 mL of water and one spatula full of copper sulphate powder. Group B takes 50 mL of water and two spatula full of copper sulphate powder in a beaker. Groups C and D can take different amounts of copper sulphate and potassium permanganate or common salt (sodium chloride) and mix the given components to form a mixture. Report the observations on the