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Chapter Analysis
Intermediate28 pages • EnglishQuick Summary
This chapter introduces the fundamental concepts of chemistry, including the classification and properties of matter, the laws of chemical combinations, and the atomic and molecular theories. It covers the significance of measurements and units, and introduces the mole concept and stoichiometry, explaining how to determine the empirical and molecular formulas for compounds. The chapter also highlights the role of chemistry in everyday life and its importance in developing various industries and solving environmental issues.
Key Topics
- •States of matter
- •Classification of matter
- •Laws of chemical combination
- •Dalton's atomic theory
- •Concept of mole
- •Stoichiometry
- •Empirical and molecular formulas
- •Significance of Avogadro's number
Learning Objectives
- ✓Explain the characteristics of three states of matter
- ✓Classify different substances into elements, compounds, and mixtures
- ✓Use scientific notations and determine significant figures
- ✓Differentiate between precision and accuracy
- ✓Explain various laws of chemical combination
- ✓Perform stoichiometric calculations
Questions in Chapter
Calculate the molar mass of the following: (i) H2O (ii) CO2 (iii) CH4
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Calculate the mass per cent of different elements present in sodium sulphate (Na2SO4).
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Determine the empirical formula of an oxide of iron, which has 69.9% iron and 30.1% dioxygen by mass.
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Calculate the amount of carbon dioxide that could be produced when (i) 1 mole of carbon is burnt in air. (ii) 1 mole of carbon is burnt in 16 g of dioxygen. (iii) 2 moles of carbon are burnt in 16 g of dioxygen.
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Calculate the mass of sodium acetate (CH3COONa) required to make 500 mL of 0.375 molar aqueous solution. Molar mass of sodium acetate is 82.0245 g mol–1.
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Additional Practice Questions
What is the significance of Avogadro's number in chemistry?
mediumAnswer: Avogadro's number, 6.022 × 10^23, defines the number of atoms, ions, or molecules in one mole of a substance, allowing chemists to count particles by weighing substances.
How do you differentiate between empirical and molecular formulas?
mediumAnswer: The empirical formula represents the simplest whole-number ratio of atoms in a compound, while the molecular formula shows the exact number of each type of atom present.
Explain the law of conservation of mass with an example.
easyAnswer: The law of conservation of mass states that in a chemical reaction, mass is neither created nor destroyed. For example, when water forms from hydrogen and oxygen, the mass of water is equal to the total mass of hydrogen and oxygen used.
What is the difference between molarity and molality?
mediumAnswer: Molarity is the number of moles of solute per liter of solution, while molality is the number of moles of solute per kilogram of solvent.
How can the purity of a chemical sample be verified?
mediumAnswer: The purity of a chemical sample can be verified by comparing its percentage composition with that of a pure sample.