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Average Rate of Reaction quiz #1

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  • How do you determine the average rate of decomposition of H3PO4 between 10.0 and 40.0 seconds?
    To determine the average rate of decomposition of H3PO4 between 10.0 and 40.0 seconds, calculate the change in concentration of H3PO4 over this time interval and divide by the change in time. Use the formula: average rate = (final concentration - initial concentration) / (final time - initial time). The result will be negative, indicating the reactant is being consumed.
  • Why is the rate of change in concentration negative for reactants during a chemical reaction?
    The rate is negative for reactants because their concentration decreases as they are consumed to form products.
  • What does the bracket notation [ ] represent in the context of reaction rates?
    The bracket notation [ ] represents the concentration of a substance, typically in molarity, at a given time.
  • How do stoichiometric coefficients affect the calculation of average reaction rates?
    Stoichiometric coefficients are used to divide the change in concentration for each reactant or product, ensuring the rates are properly scaled according to the balanced chemical equation.
  • What is the formula for calculating the change in concentration of a reactant or product?
    The change in concentration is calculated as final concentration minus initial concentration.
  • How is the average rate of product formation expressed mathematically?
    It is expressed as the change in product concentration divided by the product's stoichiometric coefficient and the change in time.
  • What does a positive sign indicate in the rate of product formation?
    A positive sign indicates that the concentration of products is increasing as the reaction proceeds.
  • Why must the rates of disappearance of reactants and appearance of products be adjusted for stoichiometry?
    They must be adjusted so that the rates reflect the actual proportions in which reactants are consumed and products are formed according to the balanced equation.
  • What is the significance of using a balanced chemical equation when calculating reaction rates?
    A balanced equation ensures that the rates for all reactants and products are correctly related through their stoichiometric coefficients.
  • What does the term 'average rate' refer to in the context of chemical reactions?
    Average rate refers to the change in concentration of a reactant or product over a specific time interval.