Terror in the Toilet Bowl

Part 1

You really had meant well. After all, how many of your friends, going home for the weekend to

catch up on good food and clean laundry, would even have considered offering to take over their

kid sister's job of cleaning the bathroom? (The fact that she saw you replacing the smashed

taillight on your folks' car at 3am had nothing to do with it.) No, out of the goodness of your

heart, you volunteered to leave no tile unscrubbed - and what do you get? Yelled at for releasing

a cloud of toxic fumes that drove everyone from the house for half a freezing day, until things

aired out. How were you to know that your folks had switched toilet bowl cleaners? The old stuff

never did anything like that when you mixed it with the Clorox. To top it off, your folks blamed

you for not knowing better: "Why am I paying tuition for you to take a chemistry course that

doesn't teach you anything practical?! When you get back to campus, go ask that teacher to tell

you what happened - at least you'll learn something that way!"

"Hydrazine!", announced your chem prof on Monday after you had related the whole sordid tale.

"Well-known process, really - mix together some ammonia, hypochlorite, and base, and - boom!

Toxic rocket fuel that reeks of dead fish! Funny thing, though - even after all this time people

still aren't too sure of the actual mechanism of hydrazine formation. Listen - how would you like

to try to figure this out, instead of doing the regular kinetics lab? I've been interested in

this, and got one of last year's students to do a little work on it. You could start by looking over

the data that were collected and seeing what the rate law is. Picking up some extra credit

wouldn't exactly hurt, either, given your last test score."

Figuring that this was not the time to admit that you had no clue about any "rate law", you

reported that afternoon to the prof's lab, and were handed the data below:

Table 1. Initial Rates as a Function of Initial Concentrations in the Formation of

Hydrazine.

EXP.	INITIAL [NH3]	INITIAL [NaOCl]	INITIAL [OH-]	INITIAL RATE M/min
1	0.100	0.100	0.100	7.2
2	0.053	0.100	0.100	2.02
3	0.025	0.100	0.100	0.45
4	0.100	0.048	0.100	3.46
5	0.100	0.200	0.100	14.8
6	0.025	0.100	0.210	0.214
7	0.025	0.100	0.051	0.882
8	0.036	0.036	0.036	?

"I never had the chance to work up these data - can you look them over, and figure out the rate

law, including the rate constant? And please fill in the rate for that last experiment, too - I hate an

unfinished table. Oh - and one more thing. Besides these initial rate studies, Morgan also ran

some concentration vs. time experiments (data given below), but as you can see, forgot to label

which reactant was monitored in each case. You'll be able to figure that out, though, after you

plot the data."

Table 2. Reactant As Concentration as a Function of Time

[A]	0.250	0.246	0.237	0.226	0.215	0.206	0.197	0.189
t, min	0	10	30	60	90	120	150	180

Table 3. Reactant Bs Concentration as a Function of Time

[B]	0.250	0.232	0.202	0.162	0.131	0.105	0.0849	0.0683
t, min	0	10	30	60	90	120	150	180

1. What is the rate law for the reactant forming hydrazine in Table 1?

2. What rate would you expect for experiment 8? Show your work.

3. How can plotting the concentration-time data let you identify which reactant goes with which data set? Which reactant is A? B?