Reaction quotient writing

Changing Value of the Reaction Quotient Writing the Reaction Quotient... 

Provided that the pressure of hydrogen is 1 bar, we can write the reaction quotient as Q = [H "]2[C1 ]2. To find the concentration of hydrogen ions, we write the Nernst equation ... 

We can write a reactant quotient at any point during the reaction, but the most meaningful point is when the reaction has reached equilibrium. At equilibrium, the reaction quotient becomes the equilibrium constant, Kc (or Kp if gas pressures are being used). We usually express this equilibrium constant simply as a number without units since it is a ratio of concentrations or pressures. In addition,... 

If we multiply a half-reaction by any factor, E° does not change. However, the factor n before the log term and the form of the reaction quotient, Q, do change. Let s write the Nemst equation for the reaction in the preceding example, multiplied by 2 ... 

Explain why the following equilibria are heterogeneous and write the reaction quotient Q for each one. 

Section 5.10 The influence of complexation). Addition of would have an effect on both reactions but more on reaction (2) than (1) because 2 equivalents of are produced in (2) while only one in (1). You can see this effect if you write down reaction quotients for both (1) (given above already) and (2). 

The particular ratio of concentration terms that we write for a given reaction is called the reaction quotient (Q). For the reaction of N2O4 to form NO2, the reaction quotient, based directly on the balanced equation as written, is... 

To construct the reaction quotient for any reaction, write the balanced equation first. For the formation of ammonia from its elements, for example, the balanced equation (with colored coefficients for easy reference) is... 

SAMPLE PROBLEM 17.1 Writing the Reaction Quotient from the... 

Problem Write the reaction quotient, Q, for each of the following reactions ... 

Form of Q for an Overall Reaction Notice that we ve been writing reaction quotients without knowing whether an equation represents an individual reaction step or an overall multistep reaction. We can do this because we obtain the same expression for the overall reaction as we do when we combine the expressions for the individual steps. That is, if an overall reaction is the sum of two or more reactions, the overall reaction quotient (or equilibrium constant) is the product of the reaction quotients (or equilibrium constants) for the steps ... 

In general, if all the coefficients of the balanced equation are multiplied by some factor, that factor becomes the exponent for relating the reaction quotients and the equilibrium constants. For a multiplying factor n, which we can write as... 

Based on the rules for writing the reaction quotient, we have... 

At equilibrium, analysis shows that the flask contains 1.80 mol of H2, 1.80 mol of I2, and 0.520 mol of HI. We calculate Kc by finding the concentrations and substituting them into the reaction quotient. Given the balanced equation, we then write the reaction quotient ... 

As always, we start to solve the problem by writing the balanced equation and the reaction quotient ... 

Plan First, we use the balanced equation to write the reaction quotient. We can calculate the equilibrium concentrations from the given numbers of moles and the flask volume (0.32 L). Substituting these into 2c and setting it equal to the given K. (0.26), we solve for the unknown equilibrium concentration, [H2O]. 

Plan We have to And the composition of the equilibrium mixture, in other words, the equilibrium concentrations. As always, we use the balanced equation to write the reaction quotient. We find the initial [CO] and [H2O] from the given amounts (0.250 mol of each) and volume (0.125 L), use the balanced equation to define x and set up a reaction table, substitute into 2o and solve for x, from which we calculate the concentrations. 

Plan We write the reaction quotient to see how is affected by each disturbance, relative to K. This effect tells us the direction in which the reaction proceeds for the system to reattain equilibrium and how each concentration changes. 

Understand that the reaction quotient (Q) changes until the system reaches equilibrium, when it equals K , write Q for any balanced equation, and calculate K given concentrations ( 17.2) (SP 17.1) (EPs 17.5-17.18)... 

Balance each reaction and write its reaction quotient, Qc-... 

Use each of the following reaction quotients to write the balanced equation ... 

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