Stoichiometry

• Chemistry is the branch of science that studies the preparation, properties, structure, and reactions of material substances
• Chemistry developed mainly in the form of Alchemy and Iatrochemistry during 1300-1600 CE
• Modern chemistry took shape in 18th century Europe after alchemical traditions introduced by the Arabs
• After studying this unit, students will be able to:

  • Appreciate India's contribution to the development of chemistry
  • Understand the role of chemistry in different spheres of life
  • Explain the characteristics of the three states of matter
  • Classify substances into elements, compounds, and mixtures
  • Use scientific notations and determine significant figures
  • Differentiate between precision and accuracy
  • Define SI base units and convert physical quantities between systems
  • Explain various laws of chemical combination
  • Appreciate the significance of atomic mass, average atomic mass, molecular mass, and formula mass
  • Describe the terms mole and molar mass
  • Calculate the mass per cent of component elements in a compound
  • Determine empirical and molecular formulas for a compound from experimental data
  • Perform stoichiometric calculations
• Chemistry is the science of molecules and their transformations
• Ancient Indian chemistry, known as Rasayan Shastra, included metallurgy, medicine, cosmetics, glass, and dyes
• Archaeological findings in Mohenjodaro and Harappa show early chemical processes like pottery production and use of gypsum cement
• Indian chemistry included knowledge of chemical processes and techniques, such as copper metallurgy dating back to chalcolithic cultures
• Ancient Indian texts describe the preparation of gunpowder mixture and the making of soaps using mustard oil and alkalies
• Indian scientists like Nagarjuna and Chakrapani made significant contributions to chemistry, including the formulation of mercury compounds and the invention of soap
• Ancient Indian literature aligns with modern scientific findings, describing the preparation of various substances like acids and oxides
• Acharya Kanda, born in 600 BCE, was the first proponent of the 'atomic theory' in India, conceptualizing it around 2500 years before John Dalton
• Charaka Samhita is the oldest Ayurvedic epic of India, describing the treatment of diseases
• The concept of reduction of particle size of metals is discussed in Charaka Samhita, with extreme reduction termed as nanotechnology
• Bhasmas of metals are used in the treatment of ailments, with modern research showing that bhasmas have nanoparticles of metals
• After the decline of alchemy, Iatrochemistry reached a steady state but declined due to the introduction of the Western medicinal system in the 20th century
• During a period of stagnation, the pharmaceutical industry based on Ayurveda continued to exist but gradually declined
• It took about 100-150 years for Indians to learn and adopt new techniques, during which foreign products poured in, leading to a decline in indigenous traditional techniques
• Modern science appeared in the Indian scene in the later part of the nineteenth century, with European scientists coming to India and the growth of modern chemistry
• Chemistry deals with the composition, structure, properties, and interaction of matter, being of much use to human beings in daily life
• Chemistry is often intertwined with other branches of science and plays a central role in diverse areas such as weather patterns, brain function, and computer operation
• Chemistry contributes significantly to the national economy and plays a crucial role in meeting human needs for food, healthcare products, and materials to improve quality of life
• Chemistry has helped in the development and growth of nations, allowing the design and synthesis of new materials with specific properties like superconducting ceramics and conducting polymers
• Chemistry has contributed to dealing with environmental degradation, providing safer alternatives to environmentally hazardous substances like CFCs
• Chemistry has intellectual challenges for future generations, including understanding biochemical processes, using enzymes for large-scale production, and synthesizing new materials
• Chemistry is essential for a developing country like India, requiring talented and creative chemists to address challenges and contribute to growth
• Matter is anything that has mass and occupies space, with everything around us composed of matter
• Matter can exist in three physical states: solid, liquid, and gas, with different characteristics for each state
• States of matter can be interconverted by changing temperature and pressure, with solids changing to liquids and then gases upon heating
• Matter can be classified as mixtures or pure substances, with mixtures further divided into homogeneous and heterogeneous mixtures
• Pure substances have fixed compositions, with elements consisting of only one type of atom and compounds having different types of atoms
• Elements like sodium, copper, silver, hydrogen, and oxygen consist of atoms of one type
• Atoms of different elements are different in nature
• Some elements, like sodium or copper, contain atoms as their constituent particles, while in others, the constituent particles are molecules formed by two or more atoms
• Hydrogen, nitrogen, and oxygen gases consist of molecules where two atoms combine to give their respective molecules
• The constituents of a compound cannot be separated into simpler substances by physical methods, only by chemical methods
• The properties of a compound are different from those of its constituent elements
• When two or more atoms of different elements combine in a definite ratio, a molecule of a compound is obtained
• The SI system allows the use of prefixes to indicate multiples or submultiples of a unit
• Elements are present in a compound in a fixed and definite ratio, which is characteristic of that compound