Rate of Reaction

Page 1:

  • The speed of a reaction is measured by the rate of reaction.

  • The rate of reaction is monitored by studying the concentration of species over time.

  • The concentration is measured in molarity (mol).

  • The time is measured in seconds.

  • The concentration of the species decreases over time.

  • The species is a reactant in the reaction.

Page 2:

  • The change in concentration of the species during the first 10 seconds is -6.1520 M.

  • The change in concentration of the species between the 60 and 70 second marks is 0.0301 M.

  • The rate of change for this species is not the same during these two time periods.

  • The average rate of change for the chemical species in the first 10 seconds is -0.028 M/s.

  • The average rate of change for the chemical species between 30 and 40 seconds is 0.0075 M/s.

  • The average rate of change for the chemical species between 60 and 70 seconds is -0.0025 M/s.

  • The rates calculated are negative because the amount of reactant is decreasing.

Page 3:

  • The graph in Model 2 contains data about a second species in the reaction.

  • The solid line in Model 2 is the same line as in Model 1.

  • The new data illustrates the change in concentration of a product of the reaction.

  • The average rate of change for species B in the first 10 seconds is 0.055 M/s.

  • The average rate of change for species B between 30 and 40 seconds is 0.015 M/s.

  • The average rate of change for species B between 60 and 70 seconds is 0.005 M/s.

Page 4:

  • The calculations performed in the previous questions are summarized in a table.

  • The chemical reaction that best describes the reaction studied for Model 2 is A + 2B -> 2B.

  • The rate of reaction is determined by the rate of change for a species with a coefficient of one in the balanced reaction.

  • The initial rate of reaction for the chemical process investigated in Model 2 is 0.0285 M/s.

  • The initial rate of change for hydrogen in the given reaction is -0.18 M/s.

  • The initial rate of change for ammonia in the given reaction is 0.12 M/s.

  • The initial rate of reaction for the given reaction is 0.06 M/s.

Page 5:

  • The rate curves for nitrogen and ammonia need to be sketched based on the given graph.

  • The initial concentration of nitrogen is 0.500 M.

  • There is no presence of ammonia initially.

Page 6: Extension Questions

Question 13: Matching lab tools with situations

  • A. pH meter

    • Used to monitor a reaction that involves an acidic or basic reactant or product.

  • B. Manometer

    • Used to monitor a reaction that involves a gaseous reactant or product.

  • C. Spectrophotomer

    • Used to monitor a reaction that involves a colored reactant or product.

  • D. Thermometer

    • Used to monitor a reaction that is exothermic or endothermic, with a known enthalpy.

  • E. Optical rotation polarimeter

    • Used to monitor a reaction that involves a chiral (optically active) reactant or product.

Question 14: Reaction rate of N2O4(g) 2NO2 (g)

  • The rate of the reaction can be studied at constant temperature using a pressure probe.

  • If the reaction vessel initially contained only dinitrogen tetroxide:

    • Expect an overall increase in pressure as the reaction proceeds.

    • Justification: The number of moles double, increasing the number of collisions and thus increasing pressure.

  • If the reaction showed an increase of 0.500 kPa in 10 seconds:

    • The change in pressure for dinitrogen tetroxide in the same time period would be