The following represents the effect of time on the concentration during a reaction. The upper line represents a reactant concentration and the lower line the concentration of a product. Which of the following statements is not correct? Concentration. B C Time- O Between points A and D the reactant concentration is decreasing. O Between points B and C the product concentration is increasing. At point D the rate of the forward and reverse reactions are the same. O At point C the rate of product breakdown equals that of reactant consumption.

The following represents the effect of time on the concentration during a reaction. The upper line represents a reactant concentration and the lower line the concentration of a product. Which of the following statements is not correct? Concentration. B C Time- O Between points A and D the reactant concentration is decreasing. O Between points B and C the product concentration is increasing. At point D the rate of the forward and reverse reactions are the same. O At point C the rate of product breakdown equals that of reactant consumption.

Chemistry: Matter and Change

1st Edition

ISBN:9780078746376

Author:Dinah Zike, Laurel Dingrando, Nicholas Hainen, Cheryl Wistrom

Publisher:Dinah Zike, Laurel Dingrando, Nicholas Hainen, Cheryl Wistrom

Chapter17: Chemical Equilibrium

Section: Chapter Questions

Problem 1STP

See similar textbooks

Similar questions

. Explain what it means that a reaction has reached a state of chemical equilibrium. Explain why equilibrium is a dynamic state: Does a reaction really “stop” when the system reaches a state of equilibrium? Explain why, once a chemical system has reached equilibrium, the concentrations of all reactants remain constant with time. Why does this constancy of concentration not contradict our picture of equilibrium as being dynamic? What happens to the rates of the forward and reverse reactions as a system proceeds to equilibrium from a starting point where only reactants are present?
Which reaction mechanism assumptions are unimportant in describing simple ionic reactions between cations and anions? Why?
Substances that poison a catalyst pose a major concern for many engineering designs, including those for catalytic converters. One design option is to add materials that react with potential poisons before they reach the catalyst. Among the commonly encountered catalyst poisons are silicon and phosphorus, which typically form phosphate or silicate ions in the oxidizing environment of an engine. Group 2 elements are added to the catalyst to react with these contaminants before they reach the working portion of the catalytic converter. If estimates show that a catalytic converter will be exposed to 625 g of silicon during its lifetime, what mass of beryllium would need to be included in the design?
Classify each of the following statements as true or false. aSome equilibria depend on a steady supply of a reactant in order to maintain the equilibrium. bBoth forward and reverse reactions continue after equilibrium is reached. cEvery time reactant molecules collide, there is a reaction. dPotential energy during a collision is greater than potential energy before or after the collision. eThe properties of a transition state are between those of the reactants and products. fActivation energy is positive for both the forward and reverse reactions. gKinetic energy is changed to potential energy during a collision. hAn increase in temperature speeds the forward reaction but slows the reverse reaction. iA catalyst changes the steps by which a reaction is completed. jAn increase in concentration of a substance on the right-hand side of an equation speeds the reverse reaction rate. kAn increase in the concentration of a substance in an equilibrium increases the reaction rate in which the substance is a product. lReducing the volume of a gaseous equilibrium shifts the equilibrium in the direction of fewer gaseous molecules. mRaising temperature results in a shift in the forward direction of an endothermic equilibrium. nThe value of an equilibrium constant depends on temperature. oA large K indicates that an equilibrium is favored in the reverse direction.
How do chemists envision reactions taking place in terms of the collision model for reactions? Give an example of a simple reaction and how you might envision the reaction’s taking place by means of a collision between the molecules.
Determine rxnH 25 C for the following reaction: NO g O2 g NO2 g This reaction is a major participant in the formation of smog.
. Account for the increase in reaction rate brought about by a catalyst.
Classify each of the reactions according to one of the four reaction types summarized in Table 18.1. (a) Fe2O3(s) + 2 Al(s) 2 Fe(s) + Al2O3(s) rH = 851.5 kj/mol-rxn rS = 375.2 J/K mol-rxn (b) N2(g) + 2 O2(g) 2 NO2(g) rH = 66.2 kJ/mol-rxn rS = 121.6 J/K mol-rxn TABLE 18.1 Predicting Whether a Reaction Will Be Spontaneous Under Standard Conditions
The boxes shown below represent a set of initial conditions for the reaction: Draw a quantitative molecular picture that shows what this system looks like after the reactants are mixed in one of the boxes and the system reaches equilibrium. Support your answer with calculations. Consider an equilibrium mixture of four chemicals (A, B, C, and D, all gases) reacting in a closed flask according to the foll owing equation: A+BC+D a. You add more A to the flask. How does the concentration of each chemical compare to its original concentration after equilibrium is re-established? Justify your answer. b. You have the original set-up at equilibrium, and add more D to the flask. How does the concentration of each chemical compare to its original concentration after equilibrium is re-established? Justify your answer.
For each of the changes listed will the rate of the following chemical reaction increase, decrease, or remain the same? Cu(s)+H2SO4(aq)CuSO4(aq)+H2(g) a. the concentration of H2SO4 is increased b. the copper is ground into a powder c. the mixture is stirred rapidly d. the temperature of the solution is increased
The following series of diagrams represent the reaction XY followed over a period of time. The X molecules are red and the Y molecules are green. At the end of the time period depicted, has the reaction system reached equilibrium? Justify your answer with a one-sentence explanation.
. In your own words, paraphrase Le Châtelier’s principle. Give an example (including a balanced chemical equation) of how each of the following changes can affect the position of equilibrium in favor of additional products for a system: the concentration of one of the reactants is increased: one of the products is selectively removed from the system: the reaction system is compressed to a smaller volume: the temperature is increased for an endothermic reaction: the temperature is decreased for an exothermic process.