CHG 3331 Lecture 3: Tutorial 6-Example 25.2
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The following data were collected at 20 oC for the reaction of bromophenol blue (HBPB2-) and hydroxide ions (OH-):
HBPB2- (aq) + OH- (aq) ---> BPB3- (aq) + H2O (l)
The times required to form a constant [BPB3-] at varying initial concentrations of reactants were determined and tabulated. From the rate data, determine the rate law for the reaction.
trial | [OH-] | [HBPB2-] | reaction time (sec) | rate (1/sec) |
1 | 1.00 | 7.22 x 10-6 | 75 | |
2 | 0.25 | 7.22 x 10-6 | 290 | |
3 | 1.00 | 3.63 x 10-6 | 152 |
rate = k[HBPB2-]2[OH-] | ||
rate = k[HBPB2-]2[OH-]2 | ||
rate = k[HBPB2-][OH-] | ||
rate = k[HBPB2-][OH-]2 |
QUESTION 2
Which of the following balanced molecular equations represent reactions for which the rate law expression could likely be determined via time to turbidity determinations? Select all that apply.
a. | 2 KI (aq) + Pb(NO3)2 (aq) ---> PbI2 (s) + 2 KNO3 (aq) | |
b. | 2 HBr (aq) + Ca(OH)2 (aq) ---> 2 H2O (l) + CaBr2 (aq) | |
c. | 2 NO (g) + 5 H2 (g) ---> 2 NH3 (g) + 2 H2O (g) | |
d. | FeS (s) + HCl (aq) ---> FeCl2 (aq) + H2S (g) | |
e. | 3 SrCl2 (aq) + 2 Li3PO4 (aq) ---> Sr3(PO4)2 (s) + 6 LiCl (aq) |
QUESTION 3
When working in the laboratory a small amount of 0.30 M sodium thiosulfate accidentally splashes on your exposed forearm. What should you do? Select all that apply.
a. | Inform your lab instructor. | |
b. | Proceed immediately to the sink in the laboratory and flush the area with copious amounts of water. Then wash the area with mild hand soap. | |
c. | Leave the laboratory immediately. All lab work is over for you today. | |
d. | Do nothing. | |
e. | Stop, drop, and roll. |
QUESTION 4
volume of 1.0 M HCl | volume of water | volume of 0.3 M Na2S2O3 | |
well 1 | 2.0 mL | 0 | 3.0 mL |
well 2 | 2.0 mL | 1.5 mL | 1.5 mL |
well 3 | 2.0 mL | 2.0 mL | 1.0 mL |
The above table summarizes the amounts and concentrations of the reactants that will be used in each trial in Parts II. Use the dilution equation, M1V1 = M2V2, to calculate the concentration Mf (molarityfinal) of Na2S2O3 in each well after mixing but before any reaction occurs. The [HCl] has been worked for you as an example.
M1(HCl)V1 = M2(HCl)V2 where V2 = final total volume Vf
(1.0 M)(2.0 mL) = M2(HCl)(5.0 mL)
M2(HCl) = 0.40 M = Mf(HCl)
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