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1. For parts of the free-response question that require calculations, clearly show the method used
and the steps involved in arriving at your answers. You must show your work to receive creditfor your answer. Examples and equations may be included in your answers where appropriate.
The dissolution of is represented above.
(a) Write a mathematical expression that can be used to determine the value of , the molarsolubility of . (Do not do any numerical calculations.)
Please respond on separate paper, following directions from your teacher.
(b) If is dissolved in , is the maximum possible concentration of in the solution greater than, less than, or equal to the concentration of inthe solution in part ( ) ? Explain.
Please respond on separate paper, following directions from your teacher.
Compound
(c) A table showing values for several lead compounds is given above. A saturatedsolution of which of the compounds has the greatest molar concentration of ? Explain.(Do not do any numerical calculations.)
Please respond on separate paper, following directions from your teacher.
Select a point value to view scoring criteria, solutions, and/or examples and to score the response.
0 1
The response gives the equation OR (or a variation).
Part (b)
Select a point value to view scoring criteria, solutions, and/or examples and to score the response.
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The response meets both of the following two criteria:
The amount of that dissolved in the solution is less than the amount of that dissolved in the original solution.
The high concentration of in the solution suppresses the dissolution of because less can form before the product equals or exceeds thevalue of .
Part (c)
Select a point value to view scoring criteria, solutions, and/or examples and to score the response.
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has the largest .
2. For parts of the free-response question that require calculations, clearly show the method used
and the steps involved in arriving at your answers. You must show your work to receive creditfor your answer. Examples and equations may be included in your answers where appropriate.
Gas Initial Concentration ( )0.030
0.015
Samples of three gases, , , and , were combined in a rigid vessel. The initialconcentrations of and are given in the table above.
Please respond on separate paper, following directions from your teacher.
Equilibrium was established at a certain temperature according to the following chemicalequation.
After equilibrium was established, the concentration of was .
(b) On the graph above, carefully draw three curves, one for each of the three gases, startingfrom the initial points you drew in part ( ). The curves must show how the concentration ofeach of the three gases changed as equilibrium was established.
Please respond on separate paper, following directions from your teacher.
, , and are at equilibrium at a different temperature in a different vessel.
Please respond on separate paper, following directions from your teacher.
(d) Does the value of increase, decrease, or remain the same when the temperature isdecreased? Justify your answer based on the expression for and the concentrations of theproduct and reactants.
Please respond on separate paper, following directions from your teacher.
(e) In the following empty box, draw an appropriate number of each type of molecule torepresent a possible new equilibrium at the lower temperature.
Please respond on separate paper, following directions from your teacher.
Part (a)
Select a point value to view scoring criteria, solutions, and/or examples and to score the response.
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The diagram meets both of the following criteria:
The partial pressure of is plotted at at time , and the point is labeled.
Part (b)
Select a point value to view scoring criteria, solutions, and/or examples and to score the response.
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The response meets all of the following criteria:
The curve for decreases to and levels off.
The curve for decreases to and levels off.
The curve for increases to and levels off.
Part (c)
Select a point value to view scoring criteria, solutions, and/or examples and to score the response.
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The response indicates that the system shifts to the right because the forward reaction is exothermic.
Part (d)
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The response meets both of the following criteria:
The response indicates that .
The response indicates that if and decrease and increases, must increase.
Part (e)
Select a point value to view scoring criteria, solutions, and/or examples and to score the response. Theresponse should be consistent with the answer to part (d).
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The response meets both of the following criteria:
There is one molecule and one molecule in the box.
