Class 7 Science - ICSE-CHEMISTRY
Water
The Class 7 ICSE Chemistry chapter on Water explores water as a universal solvent, its physical and chemical properties, and its vital role in supporting life. Students learn about solutions, solubility, and the difference between saturated and unsaturated solutions. The chapter also covers the presence of water of crystallization in hydrated salts, the causes and effects of water pollution, and methods of water purification like sedimentation, filtration, and chlorination. This chapter is essential for ICSE board exams as it forms the foundational building block for advanced chemical solutions, concentration calculations, and environmental chemistry in higher classes.
Start Learning FreeKey Concepts
Universal Solvent
Water is called a universal solvent because it can dissolve a wide variety of substances, both solids and gases, more than any other liquid.
Solution, Solute, and Solvent
A solution is a homogeneous mixture formed when a solute (the substance that dissolves) is completely dissolved in a solvent (the dissolving medium).
Saturated and Unsaturated Solutions
An unsaturated solution can dissolve more solute at a given temperature, whereas a saturated solution has reached its maximum capacity and cannot dissolve any more solute.
Water of Crystallization
It is the fixed amount of water molecules chemically bound in a definite proportion within a crystalline salt, such as copper sulfate pentahydrate.
Water Pollution
The contamination of water bodies by harmful human activities, industrial waste, and agricultural runoff, making it unsafe for consumption and aquatic life.
Important Formulas
Board Exam Info
In ICSE Chemistry Class 7, this chapter typically carries around 6 to 8 marks in the final examinations. Questions frequently include defining terms like universal solvent and saturation, differentiating between soft and hard water or soluble and insoluble substances, explaining methods of water purification, and identifying water of crystallization in specific chemical formulas.
Frequently Asked Questions
Why is water called a universal solvent?
Water is called a universal solvent because its polar molecules enable it to dissolve a vast number of ionic and covalent compounds compared to any other liquid.
What is the difference between a saturated and an unsaturated solution?
An unsaturated solution can dissolve more solute at room temperature, while a saturated solution holds the maximum amount of solute and cannot dissolve any more.
What does water of crystallization mean?
It refers to the fixed number of water molecules that are trapped inside the crystal structure of certain salts, giving them their specific shape and color.
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