Module 8/11
1. Equilibrium is established for the reaction 2X (s) + Y(g) ⇄2Z (g) at 500K, Kc= 100. Determine the concentration of Z in equilibrium with 0.2 mol X and 0.50 M Y at 500K.
7.1M
5. Calculate the pH and pOH
Problem 1. Solution 1 : [H+ ] = 6.7 x 10-5
Problem 2. Solution 2 : [OH- ] = 9.2 x 10-3
Problem 1: pH = 4.17, pOH = 9.82
Problem 2: pH = 11.97, pOH = 2.03
9. Consider a 0.10 M solution of mehylamine with a Kb of 4.4 x 10^-4. Calculate the OH concentration and the pH of the solution.
pOH: 2.19
pH: 11.81
14. Calculate the pH of a 0.021 M NaCN solution [Ka (HCN)= 4.9 E -10]
10.82
What is the only mammal capable of true sustained flight?
Bat
2. Which is the correct equilibrium constant expression for the rxn:
Fe2O3 (s) + 3H2 (g) = 2Fe (s) + 3 H2O (g)
Kc = [H2O]3 / [H2]3
6. For the equilibrium reaction 2SO2 (g) + O2 (g) -> 2SO3 (g), Horxn= -198 kJ/mol. Which one of these factors would cause the equilibrium constant to increase
Decrease the temperature
A 0.14 M HNO3 solution is 5.7% ionized. Calculate the H+ ion concentration
8.0 E -3 M
15. A 15.0 mL sample of 0.200 M NaOH is titrated with 0.250 M of HCl. Calculate the pH of the mixture after 10.0 mL of acid have been added.
12.3
Which element has the highest melting point of all known elements?
Tungsten (W)
3. Calculate Kp for the reaction 2NOCl (g) = 2NO (g) + Cl2 (g) at 400°C for Kc = 2.1 E -2 at 673 K
1.2
7. In which of these gas-phase equilibria is the yield of products increased by increasing the total pressure on the reaction mixture?
a. 2NO (g) + Cl2 (g) -> 2NOCl (g)
b. 2SO3 (g) -> 2SO2 (g) + O2 (g)
PCl5 (g) -> PCl3 (g) + Cl2 (g)
CO (g) + H2O (g) -> CO2 (g) + H2 (g)
None of these
2NO (g) + Cl2 (g) -> 2NOCl (g)
11. What mass of ammonium chloride must be added to 250mL of water to give a solution with pH=4.85? [Kb (NH3)= 1.8x10-5]
4.78
16. What mass of sodium fluoride must be added to 250 mL of a 0.10M HF solution to give a buffer solution having a pH of 3.5? (Ka (HF) = 7.1x10-4)
2.35g NaF
Which empire was ruled by Genghis Khan?
The Mongol Empire
4. The following reactions occur at 500 K. Arrange them in order of increasing tendency to proceed to completion (least completion to greatest completion)
2 NOCL -> 2 NO + CL2 Kp = 1.7 E -2
N2O4 -> 2NO2 Kp = 1.5 E 3
2SO3 -> 2SO2 + O2 Kp = 1.3 E-5
2NO2 -> 2NO + O2 Kp = 5.9 E -5
3, 4, 1, 2
8. In the reaction:
HSO4- + OH- = SO42- + H20
The conjugate acid-base pairs are
HSO4 - and SO4 2- ; H2O and OH-
12.The pH of a certain solution is 2.0. How many H+ (aq) ions are there in 1L of the solution?
6.02 E21 H+ Ions
17. What is the pH at equivalence point in the titration of 100mL of 0.10M HCN (Ka=4.9x10-10) with 0.10 M NaOH?
11
Which city was formerly known as Byzantium and later Constantinople?
Istanbul
19. What is the pH of the solution when 18.0 mL of 0.20 M HI is titrated with 25.0 mL of 0.10 M LiOH?
1.59
20. What is the pH of the solution when you titrate 25.0 mL of 0.10 M propionic acid (CH₃CH₂COOH) with 10.0 mL of 0.10 M KOH? The Ka of propionic acid is 1.3×10−5
4.71
13. What is the OH- ion concentration in 5.2 E -4 M HNO3 solution?
1.9 E-13 M
18. What is the pH of the solution when you titrate 30.0 mL of 0.10 M HNO₃ with 12.0 mL of 0.15 M KOH?
1.57
In biochemistry, what molecule is commonly referred to as the “energy currency” of the cell?
ATP (Adenosine Triphosphate)