The 'water-gas shift reaction' is used as an industrial source of hydrogen: CO(g) + H2O(g) CO2(g)...

   

 

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The 'water-gas shift reaction' is used as an industrial source of hydrogen: CO(g) + H2O(g) CO2(g) + H2(g) The equilibrium constant for this reaction is 10.0 at 750 K (standard state = 1 mol/L).. A mixture of CO2 (2.0 mol/L) and H2 (4.0 mol/L) was prepared and allowed to come to equilibrium (at 750 K). What is the concentration of CO2 in the mixture equilibrium? Student Answer (line numbers on the left): 1 CO(g) + H2O(g) CO2(g) + H 2 initial: 0 0 2.0 4.0 3 change: +x +x -X 4 equilibrium: x [CO2][H2] (2.0-x) x (4.0-x). XXX -X 2.0 x 4.0-x 10.0 Assume x is small, which simplifies this equation to: 5 K = [CO][H,O] == 6 2.0 x 4.0 7 = 10.0 xxx 8 8.0 10.0x 9 x=0.89 10 [CO2]=0.89 mol L-1 (a) (i) There is an error in lines 1-7 of the student answer. Which line contains the error and what is the error? [1 mark] (ii) How could you confirm that this is an error? [2 marks] I (iii) What property of the reaction (that is, a value given in the textbook question) gives a warning that might lead to avoiding this error? [2 marks] The 'water-gas shift reaction' is used as an industrial source of hydrogen: CO(g) + H2O(g) CO2(g) + H2(g) The equilibrium constant for this reaction is 10.0 at 750 K (standard state = 1 mol/L).. A mixture of CO2 (2.0 mol/L) and H2 (4.0 mol/L) was prepared and allowed to come to equilibrium (at 750 K). What is the concentration of CO2 in the mixture equilibrium? Student Answer (line numbers on the left): 1 CO(g) + H2O(g) CO2(g) + H 2 initial: 0 0 2.0 4.0 3 change: +x +x -X 4 equilibrium: x [CO2][H2] (2.0-x) x (4.0-x). XXX -X 2.0 x 4.0-x 10.0 Assume x is small, which simplifies this equation to: 5 K = [CO][H,O] == 6 2.0 x 4.0 7 = 10.0 xxx 8 8.0 10.0x 9 x=0.89 10 [CO2]=0.89 mol L-1 (a) (i) There is an error in lines 1-7 of the student answer. Which line contains the error and what is the error? [1 mark] (ii) How could you confirm that this is an error? [2 marks] I (iii) What property of the reaction (that is, a value given in the textbook question) gives a warning that might lead to avoiding this error? [2 marks]