Stoichiometry

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Overview

Stoichiometry is a branch of chemistry that deals with the quantitative relationships between reactants and products in a balanced chemical equation. It involves using the mole concept to calculate the relative quantities of substances involved in a chemical reaction. Stoichiometry helps in understanding how reactants combine and in what proportions to form products, following the laws of conservation of mass and definite proportions. It allows for the calculation of mass-mass, mass-mole, and mass-volume relationships in chemical reactions, providing valuable information about the substances involved.

Questions and Answers

  1. What is stoichiometry and its significance in chemistry?

    Stoichiometry is the quantitative relationship between reactants and products in a balanced chemical equation. It helps in determining the amounts of substances involved in a chemical reaction.

  2. How does stoichiometry relate to the law of conservation of mass?

    Stoichiometry is based on the law of conservation of mass, which states that mass is neither created nor destroyed in a chemical reaction. Stoichiometry ensures that the total mass of reactants equals the total mass of products.

  3. What are the assumptions made in stoichiometry calculations?

    In stoichiometry calculations, it is assumed that all reactants are completely converted into products, and no side reactions occur.

  4. How can stoichiometry be applied to determine mass-mass relationships in chemical reactions?

    Stoichiometry allows us to calculate the mass of one substance based on the given mass of another substance involved in the chemical reaction.

  5. What is the law of definite proportions and how does it relate to stoichiometry?

    The law of definite proportions states that a chemical compound always contains the same elements in the same proportion by mass. Stoichiometry ensures that reactants combine in fixed ratios according to this law.

Multiple-Choice Questions

  1. What is stoichiometry?

    a) The study of atoms
    b) The study of chemical elements
    c) The study of quantitative relationships in chemical reactions
    d) The study of physical properties
    Answer: c) The study of quantitative relationships in chemical reactions

  2. Which law is obeyed during stoichiometric calculations?

    a) Law of gravity
    b) Law of conservation of energy
    c) Law of conservation of mass
    d) Law of motion
    Answer: c) Law of conservation of mass

  3. What does Avogadro's number help to explain in stoichiometry?

    a) Relationship between reactants and products
    b) Mass-mass relationships
    c) Mole-mole calculations
    d) Relationship between moles and volume
    Answer: a) Relationship between reactants and products

  4. How do we calculate the percentage yield of a chemical reaction?

    a) Actual yield divided by theoretical yield multiplied by 100
    b) Theoretical yield divided by actual yield multiplied by 100
    c) Actual yield minus theoretical yield
    d) Theoretical yield plus actual yield
    Answer: a) Actual yield divided by theoretical yield multiplied by 100

  5. What is a mass-mass relationship in stoichiometry?

    a) Calculating the mass of reactants
    b) Calculating the mass of products
    c) Calculating the mass of one substance from the mass of another in a chemical reaction
    d) Calculating the mass of elements in a compound
    Answer: c) Calculating the mass of one substance from the mass of another in a chemical reaction