1. Define equilibrium.
2. Write the equilibrium expression for the following equation:
4NH3 + 7O2 <---> 4NO2+ 6H2O (all gases)
3. In certain experiment, 1.22 mol of NH3 was placed in an empty 1.00 L flask at 500C. After equilibrium was reached, 0.399 mol of N2was found to be in the flask. Calculate the concentration of the ammonia and H2 at equilibrium.
4. When 0.45 moles of PCl5 is heated in a 10 liter container an equilibrium is established in which 0.21 moles of Cl2 is present. PCl5 <---> PCl3 + Cl2 (all gases) What is the equilibrium constant?
5. Given the following equation; N2 + 3H2 <---> 2NH3 Keq = 0.105
Predict the direction that the equilibrium will shift if the initial concentration are as follows.
N2 = 2.0M H2 = 2.0M NH3= 2.0M
6. How many moles of HI are present at equilibrium when 2.5 mole of H2 is mixed with 2.5 mole of I2 in a 0.5 liter container? H2 + I2 <---> 2HI Keq = 50
7. 1.0 mole of N2 and 1.0 mole of O2 and 2.0 moles of NO are placed into a one liter container. What is the equilibrium concentration of NO? N2 + O2 <---> 2NO Keq = 0.10
8. The initial partial pressure of N2 and O2 are 0.80atm and 0.20 atm respectively. What is the partial pressure of the NO at equilibrium N2 + O2 <---> 2NO Kp = 0.50
Given the following equilibrium
2CO(g) <---> C(s) + CO2(g) DH = +85KJ/mol Kp = 0.25/atm
9. Write the equilibrium expression.
10. In which direction will the equilibrium shift if the concentration of CO is increased?
11. In which direction will the equilibrium shift if the concentration of CO2 is increased?
12. In which direction will the equilibrium shift if the concentration of CO is decreased?
13. In which direction will the equilibrium shift if more carbon is added?
14. What will happen to the concentration of CO if heat is added?
15. What will happen to the value of the equilibrium constant if the concentration of CO is increased?
16. In which direction will the equilibrium shift if a catalyst is added?
17. In which direction will the equilibrium shift if argon gas is added?
18. In which direction will the equilibrium shift some carbon is removed?
Answers:
1. In a closed system, the rate of the forward rxn = the rate of the reverse rxn.
2.K = [NO2]4[H2O]6 / [NH3]4[O2]7
3. [H2] =1.2M, [NH3]=0.422M
4. K = 0.0184
5. Q=0.25 therefore eq. will shift left
6. [HI] = 7.8M therefore 3.9 moles of HI will be in the 0.5L container at eq.
7. [NO] = 0.55M
8. [NO] = 0.192Atm.
9. K= [CO2] / [CO]2
10 Right
11. Left
12. Left
13. no shift
14. shift to the right therefore CO will decrease
15. No effect. Only temp will change the value of the constant
16. No shift. A catalyst will catalyze both the forward and reverse rxn.
17. No shift.
18.No shift. The concentration of a solid does not change.