Ch. 15 & 16 (& 19.7) equilibrium I     test                   80 points                                  AP chemistry

In problems involving any calculation, show your work in an organized manner, include (i) any relevant equation (or formula), (ii) conversion factor(s), (iii) put the proper units in your calculations and answer, and (iv) have the proper number of significant figures in your answer.

1. In regards to the reaction:  H2(g)  +  Cl2(g)  → 2 HCl(g)  at equilibrium is perturbed by ___; what is the effect on the number of moles of chlorine gas ?  Justify / rationalize your response.  The temperature is constant unless stated otherwise.  [15 points]

a.  Decrease the temperature

b.  add a catalyst

c. add helium, an inert gas, at constant pressure

2.  Estimate the numerical value of the equilibrium constant for the reaction:  N2(g)  +  3 H2(g)  →  2 NH3(g)  at 37 ºC.  [10 points]

3. In regards to the reaction:  N2(g)  +  3 H2(g)  →  2 NH3(g)  at 37 ºC, what is the numerical value of Kp based on the following information:  the initial concentration of N2, H2, and NH3 is 1.0 mM, 2.0 mM, and 3.0 mM, respectively, and at equilibrium, the concentration of hydrogen gas is 1.5 mM.  [15 points]

4. What is the pH of an aqueous solution of 25.0 mM sodium lactate ?  [15 points]

5.  What is the pH of an aqueous solution of 25.0 mM methylamine ?  [15 points]

6.  old topic:  In the redox titration:    

At the equivalence point, it took 25 mL of 75 mM Mn +2  to react with 125 mL NaBiO3  -  what is the [NaBiO3] prior to the titration ?  [10 points]