2 P205 P4010 k = 1.488 MS-1 Forty-two seconds after starting the reaction, the diphosphorus pentoxide concentration is measured to be 0.0337 M. At what time will the diphosphorus pentoxide concentration be 0.0101 M?

A reaction is represented by this equation: 2W(aq)X(aq)+2Y(aq)Kc=5104 (a) Write the mathematical expression for the equilibrium constant. (b) Using concentrations of M, make up [we sets of concentrations that describe a mixture of W, X, and Y at equilibrium.

Because carbonic acid undergoes a second ionization, the student in Exercise 12.39 is concerned that the hydrogen ion concentration she calculated is not correct. She looks up the equilibrium constant for the reaction HCO,-(aq) «=* H+(aq) + COf'(aq) Upon finding that the equilibrium constant for this reaction is 4.8 X 10“H, she decides that her answer in Exercise 12.39 is correct. Explain her reasoning. A student is simulating the carbonic acid—hydrogen carbonate equilibrium in a lake: H,CO,(aq) 5=6 H+(aq) + HCO,'(aq) K = 4.4 X 10'7She starts with 0.1000 A1 carbonic acid. W hat are the concentrations of all species at equilibrium?

Characterize a system at chemical equilibrium with respect to each of the following a. the rates of the forward and reverse reactions b. the overall composition of the reaction mixture For a general reaction3A(g)+B(g)2C(g), if one starts an experiment with only reactants present, show what the plot of concentrations of A, B, and C versus time would look like. Also sketch the plot illustrating the rate of the forward reaction and rate of the reverse reaction versus time.

The following data are for the system A(g)2B(g) (a) How long does it take the system to reach equilibrium? (b) How does the rate of the forward reaction compare with the rate of the reverse reaction after 45 s? After 90 s?

. In general terms. what does the equilibrium constant for a reaction represent? What is the algebraic form of the equilibrium constant for a typical reaction? What do square brackets indicate when we write an equilibrium constant?

The reaction NO(g) + O,(g) — NO,(g) + 0(g) plays a role in the formation of nitrogen dioxide in automobile engines. Suppose that a series of experiments measured the rate of this reaction at 500 K and produced the following data; [NO] (mol L ’) [OJ (mol L 1) Rate = -A[NO]/Af (mol L_1 s-1) 0.002 0.005 8.0 X 10"'7 0.002 0.010 1.6 X 10-'6 0.006 0.005 2.4 X IO-'6 Derive a rate law for the reaction and determine the value of the rate constant.

In the PhET Reactions tab to observe how multiple atoms and molecules interact under varying conditions. Select a molecule to pump into the chamber. Set the initial temperature and select the current amounts of each reactant. Select Show bonds under Options. How is the rate of the reaction affected by concentration and temperature?

7-12 Two kinds of gas molecules are reacted at a set temperature. The gases are blown into the reaction vessel from two tubes. In setup A, the two tubes are aligned parallel to each other; in setup B, they are 900 to each other; and in setup C, they are aligned directly opposite each other. Which setup would yield the most effective collisions?

Dinitrogen trioxide decomposes to NO and NO2, in an endothermic process (rH = 40.5 kJ/mol-rxn). N2O3(g) NO(g) + NO2(g) Predict the effect of the following changes on the position of the equilibrium; that is, state which way the equilibrium will shift (left, right, or no change) when each of the following changes is made. (a) adding more N2O3(g) (b) adding more NO2(g) (c) increasing the volume of the reaction flask (d) lowering the temperature