Supplemental Instruction
Iowa State University / Leader: / Olivia
Course: / Chem 178
Instructor: / Bonaccorsi
Date:
1.What is the rate-determining step and why is it important?
The following data were measured for the reaction of BF3(g)+NH3(g) →F3BNH3(g):
Experiment / [BF3](M) / [NH3](M) / Initial Rate (M/s)1 / 0.250 / 0.250 / 0.2130
2 / 0.250 / 0.125 / 0.1065
3 / 0.200 / 0.100 / 0.0682
4 / 0.350 / 0.100 / 0.1193
5 / 0.175 / 0.100 / 0.0596
- What is the rate law for the reaction?
- What is the overall order of the reaction?
- Calculate the Rate constant with proper units.
- What is the rate when [BF3]=0.100M and [NH3]=0.500M?
2.
a. Write the rate law for a reaction between A, B, and C that is the first order in A, zero order in B, and second order in C.
b. What happens to the rate when [A] doubles and all other concentrations stay the same?
c. What happens to the rate when C is tripled and all other concentrations stay the same?
d. By what factor does the rate change if all three are tripled?
e. By what factor does the rate change if all three are cut in half?
3. Write the mass action expression for the reaction C(s) + CO2 (g) 2CO (g)
4. Find the Kc value for the overall reaction given:
1) CaO (s) + H2 (g) Ca (s) + H2O (g)K1=67
2) CaO (s) + CO (g) Ca (s) + CO2 (g)K2=490
overall: H2 (g) + CO2 (g) CO (g) + H2O (g)
5. Label if the following will favor products or reactants
K>1
K<1
K>Q
K<Q
6. For Nitrous Acid, HNO2 the Ka = 4.5*10-4. What is the Kb value for the nitrite ion, NO2-?
7. Calculate the pH of 0.1M HNO3 at 298 K.
8. Calculate the pH of 0.1 M HNO2 at 298 K. Ka=4.5x10-4
9. Initially 0.035 moles of SO2, 0.5 moles of SO2Cl2, and 0.08 moles of Cl2 are combined in a 5-liter flask. What is the value of Q and which direction will the reaction proceed to establish equilibrium?
SO2Cl2 (g) ⇄ SO2 (g) + Cl2 (g) Kc = 0.078
10. Aspirin has a pKaof 3.4. What is the ratio of A¯ to HA in:
(a) the blood (pH = 7.4)
(b) the stomach (pH = 1.4)
General comment about the solutions: You have to find the ratio between A¯ and HA so the concentrations are not needed
11. What is the hydroxide ion concentration in a solution that has a pOH of 5.70?
12. 32.00 g of sodium hydroxide were dissolved in 250.0 mL of solution to prepare the titrant. 25.00 mL of sulfuric acid were titrated with above titrant. It took 16.00 mL of sodium hydroxide solution to titrate to the end point. What is the molarity of the sulfuric acid?
2NaOH + H2SO4---> Na2SO4+ 2H2O
13. Balance this Redox Reaction:
H2S + NO3¯ ---> S8+ NO
14. In the reaction 2 NO2(g) _ N2O4(g) the initial concentration of NO2 was 0.250 M and N2O4 was 0.000 M. At equilibrium, the concentration of N2O4 was measured as 0.0133 M.
(a) Calculate the equilibrium concentration of NO2
(b) Calculate Kc.
15. What is the pH and chemical reaction of a solution containing 0.25 M HCO3- and 0.34 M Na2CO3? Ka(HCO3-)= 5.6x10-11
16. Is the following reaction spontaneous at 25 C under the following conditions:
N2 (g) + O2 (g) 2NO (g)
Nitrogen and oxygen have a pressure of 1 atm and nitrogen oxide has a pressure of 4 atm at some point during the reaction. (delta)Go=173.1 kJ.
17. For each pair, which molecule has a greater entropy?
a. CO2 (s) or CO2 (l)
b. NH3 (l) or NH3 (g)
c. Pure magnesium at 0K or 200K
18. Calculate the cell potential for a cell operating with the following reaction at 25o C, in which [MnO4 -] = 0.010 M, [Br- ] = 0.010 M, [Mn2+] = 0.15M and [H+ ] = 1.0 M.
2 MnO4 - (aq) + 10 Br- (aq) + 16 H+ (aq) 2Mn2+(aq) + 5Br2(l) + 8H2O(l)
- Consider the reaction 3CH4 (g) C3H8 (g) + 2H2 (g)
- Using ΔG0 of C3H8 = -23.47kJ and ΔG0 of H2 = 0 and ΔG0 of CH4 = -50.8, calculate, at 298K, ΔG0
- Calculate delta G at 298K if the reaction mixture consists of 40.0 atm of CH4, 0.0100atm of C3H8, and 0.0180 atm of H2.
- For a certain chemical reaction, delta H knot = -35.4 kJ and detla S knot = -85.5 J/K
- Is the reaction endothermic or exothermic?
- Does the reaction lead to an increase or decrease in the randomness or disorder of the system?
- Calculate delta G knot for the reaction at 28 degrees C
- Is the reaction spontaneous at that temperature under standard conditions