How Did James Bond Survive Being Placed in a Vat of Acid?

[davee123]

That's what I was looking for, although I think it would probably be calcium hydroxide as the main active ingredient. What if, as he was being lowered into the acid, he broke open the rebreather and dropped it, with him being high enough up to survive.

How much calcium hydroxide is in your typical rebreather? If it's not a catalyst-style reaction (which I assume it isn't since you're just mixing acids and bases), wouldn't you need roughly the same amount of calcium hydroxide to neutralize the acid? I'm not big into chemistry, but how basic is calcium hydroxide? Would it be enough to really balance out a vat that's full of acid?

Let's make a guess, here-- in order to drop him in, tank and all, the diameter of the vat is going to be at least 3-4 feet in diameter. Probably more. And it's stipulated that it's enough to just BARELY submerge him, so when he jumps in, we can assume that the height of the acid is about 6 feet. So that's at a minimum 1.5²*pi*6 cubic feet of volume (42 cubic feet), minus however much volume Bond and his suit take up.

I found one approximation that takes the normal mass and gets a rough approximation of human volume by dividing by 0.001kg/cm³. That would make Bond probably just shy of 3 cubic feet (that sounds a little small to me, but maybe not). And another few feet for his clothes and gear. So we're talking about no more than 10 cubic feet of volume for Bond and his equipment. Hence, it's a good bet that there's at least 30 cubic feet of acid to neutralize.

I'm guessing unless the calcium hydroxide reaction is catalytic (and it sounds like it isn't), there's NOT going to be enough to neutralize the acid.

DaveE

 

[jamesb-uk]

Well, the CO2 'scrubber' is made up of a variety of ingredients, although calcium hydroxide is the main ingredient. There is often some sodium hydroxide in there aswell, but I don't know what else there is- perhaps one of those could act as a catalyst.
Anyway, is your argument that there wouldn't be enough, or that the reaction wouldn't happen fast enough, because if it's the former, a catalyst won't help.

Please bear in mind that I didn't come up with this question first.

 

[davee123]

Anyway, is your argument that there wouldn't be enough, or that the reaction wouldn't happen fast enough, because if it's the former, a catalyst won't help.

Well, if it is a catalytic reaction (I assume it isn't? I don't honestly know), then yes, it'll take time, but how much time he's got isn't really stipulated in the problem. Maybe he gets the evil character to confess the whole evil plot before dropping Bond into the acid, and he winds up getting a half an hour before he's dropped into the vat. I guess you've got a potential issue there as well with the liquid stagnating (which would slow the reaction, I think?), but maybe he could drop his oxygen tank in completely (while opened slightly) so that the liquid would be more agitated and help continue to maximize the catalytic reaction's speed.

But really, I'm assuming that the reaction ISN'T a catalytic one, so that the calcium hydroxide is consumed as it neutralizes the acid. In which case, the question is, would there be sufficient calcium hydroxide to neutralize the acid to the point where it's bearable for Bond to submerge for the given 20 minutes or so?

I don't have any clue how much there is in your typical rebreather, but my Spidey-sense tells me there isn't enough. My off-the-wall guess is less than a 1 liter bottle's worth (probably less than a soda can's worth). And that's about 0.035ft³ (dunno why I picked cubic feet, but I'll go with it).

I have no idea what the minimum you'd need would be (I'm just pulling "best case" numbers out of the air here), but we do have a guess at the lower-bound amount of acid that needs to get neutralized, and that's roughly 30ft³ (see above post). So let's assume (best-case) that 1 cm³ of calcium hydroxide can neutralize 10 cm³ of the acid (I'm also assuming that volume relates to number of moles and so forth, so this is horrifically bad estimation, but it's all I've got at the moment.) If that's even modestly close to an upper bound for how much acid can be neutralized, you'd need about 3ft³ of calcium hydroxide to neutralize the acid, which sounds like WAY too much to me for him to have in his rebreather apparatus.

But, hey, I'm no chemist-- my last chemistry course was intro-level chemistry some 11 years ago. But my "common-sense" test tells me that even stretching the plausibility, it sounds like it's not even close to possible. So I'm asking if you happen to know any more details, since I could be way off. I don't know the answer, but I'm sure if we can find out roughly how much calcium hydroxide is in your average rebreather, SOMEBODY on the PF will probably be able to tell us how plausible this whole thing is.

DaveE

 

[regor60]

Well, unfortunately, this puzzle sucks since there's no real world solution

 

[jamesb-uk]

Well, if it is a catalytic reaction (I assume it isn't? I don't honestly know), then yes, it'll take time, but how much time he's got isn't really stipulated in the problem. Maybe he gets the evil character to confess the whole evil plot before dropping Bond into the acid, and he winds up getting a half an hour before he's dropped into the vat. I guess you've got a potential issue there as well with the liquid stagnating (which would slow the reaction, I think?), but maybe he could drop his oxygen tank in completely (while opened slightly) so that the liquid would be more agitated and help continue to maximize the catalytic reaction's speed.

But really, I'm assuming that the reaction ISN'T a catalytic one, so that the calcium hydroxide is consumed as it neutralizes the acid. In which case, the question is, would there be sufficient calcium hydroxide to neutralize the acid to the point where it's bearable for Bond to submerge for the given 20 minutes or so?

I don't have any clue how much there is in your typical rebreather, but my Spidey-sense tells me there isn't enough. My off-the-wall guess is less than a 1 liter bottle's worth (probably less than a soda can's worth). And that's about 0.035ft³ (dunno why I picked cubic feet, but I'll go with it).

I have no idea what the minimum you'd need would be (I'm just pulling "best case" numbers out of the air here), but we do have a guess at the lower-bound amount of acid that needs to get neutralized, and that's roughly 30ft³ (see above post). So let's assume (best-case) that 1 cm³ of calcium hydroxide can neutralize 10 cm³ of the acid (I'm also assuming that volume relates to number of moles and so forth, so this is horrifically bad estimation, but it's all I've got at the moment.) If that's even modestly close to an upper bound for how much acid can be neutralized, you'd need about 3ft³ of calcium hydroxide to neutralize the acid, which sounds like WAY too much to me for him to have in his rebreather apparatus.

But, hey, I'm no chemist-- my last chemistry course was intro-level chemistry some 11 years ago. But my "common-sense" test tells me that even stretching the plausibility, it sounds like it's not even close to possible. So I'm asking if you happen to know any more details, since I could be way off. I don't know the answer, but I'm sure if we can find out roughly how much calcium hydroxide is in your average rebreather, SOMEBODY on the PF will probably be able to tell us how plausible this whole thing is.

DaveE

I don't know- I'm not a chemist. I just heard this problem somewhere.

Ca(OH)₂+(say)H₂SO₄->2H₂0+CaSO₄

I'm still unsure about how much acid there would be or how much there would be in the rebreather. To be honest, when I heard this, I didn't really go into the answer in as much detail as you obviously want from me.

 

[davee123]

I'm still unsure about how much acid there would be or how much there would be in the rebreather. To be honest, when I heard this, I didn't really go into the answer in as much detail as you obviously want from me.

Well, junglebeast asked in post #2:

3) Is the answer you're looking for actually physically plausible?

So, the real answer should have been "I don't know", or, quite probably "no, it's not".

[edit]Looking at Sofnolime (one of the products used in rebreathers), the smallest size sold is about 10 lbs, which probably covers multiple dives (I couldn't find out how many dives with a quick search). If we assume the whole 10 lbs is used in a SINGLE dive, and assume it's solid calcium hydroxide (which it isn't), that's about 61.2 moles. And if we assume a vat of "pure" sulfuric acid, with a volume of about 30 square feet, that's approximately 15936.9 moles. So about 0.4% of the sulfuric acid would get neutralized, which does bring down the concentration of the acid, but not by a lot.[/edit]

DaveE

 

[jamesb-uk]

In my defense, I did hear this question from someone who knows quite a lot about chemistry.

What's the volume of an average person though. I've been doing a bit of research, and I've found values ranging from 1/2 m3, to 10m3(which I think is far too large). If the vat is about 0.7*2m, then he is going to be taking up quite a volume compared to the acid. The acid may not be completely pure as well, maybe only 70 or 80% of the volume could kill someone. Of course this would slow the reaction down, but there could be a long time period between inserting the chemical and him entering the acid.

Perhaps he may be harmed a little, but this may only consist of minor burns.
Perhaps he was only in there for a couple of minutes.

 

[regor60]

:zzz:

 

[davee123]

What's the volume of an average person though. I've been doing a bit of research, and I've found values ranging from 1/2 m3, to 10m3(which I think is far too large).

Well, I'm guessing Bond weighs about 180 lbs, which is roughly 81.6466266 kg. The human body is mostly water, and 1 liter of water is about 1 kg, so that's also about 81.6466266 liters, or 2.88 cubic feet. Really, the human body isn't quite as dense as water, so you can inflate that number by a bit, but I'm not sure by how much. Perhaps 3-4 cubic feet. Then there's all his gear and so forth, which probably isn't quite as voluminous as he is. But just to be safe, I was going with 10 cubic feet, tops.

If the vat is about 0.7*2m

Just to make sure I'm reading this right-- you're implying 0.7 meters in diameter, and 2 meters high? That's pretty tight. That's 27.56" of diameter, which is narrow. I'm not particularly broad shouldered, and my shoulders are about 21" from left to right. Bond is probably more like 22"-24", and that's only a scant few inches of leeway. Plus he's got diving gear.

But that aside, let's keep going with your estimate. That's 0.35m radius => 1.148' radius => 4.142 square feet base. Times a height of 2m => 6.562', which yields 27.178 cubic feet. So subtracting the best-case scenario of 10 cubic feet of "Bond", you're left with 17.178 ft³ of acid to neutralize.

So let's do more math. How many moles of molecules of acid are in the vat? Well, 17.178 ft³ is 486426.791 cm³. According to Wikipedia, Sulfuric acid is about 1.84 g/cm³, so that's about 895025.295g of Sulfuric acid. Again according to wikipedia, it's got a molar mass of 98.08 g/mol, so you're talking about 9125.462 moles of molecules of acid. Now, based on my outrageous assumption above that he's got 10 lbs of Sofnolime in his rebreather, and that it's 100% calcium hydroxide, he'd have roughly 61.2 moles with which to neutralize and dilute the acid. That's about 0.671% of the acid that's going to get diluted. Now, that's almost twice as much as I estimated before (because I think the vat ought to be bigger), but still, it's not much. And keep in mind that that's attempting to overestimate in Bond's favor by ludicrously high amounts at every turn, and we're STILL coming up with only 0.671%.

As you stated, we don't know what the pH level of the acid is-- but bringing it down by 0.671% isn't going to change it significantly.

Chances are, dissolving his air tank and other gear prior to getting in is going to have a better effect than just the calcium hydroxide, but the two in combination aren't going to do anything wonderful. They'll dilute the acid by a small margin, but since the pH level is logarithmic, I think you'd be extraordinarily lucky to even see half a point of change in the pH level.

Anyway, the bottom line seems to be that if the acid is very weak, then yes, dropping in the calcium hydroxide may be JUST enough to tip it in favor of him surviving or making it out unharmed. But he doesn't have enough to make it all that much more effective than simply dropping in, say, 15 lbs of water.

If (say) the situation were that he was about to be SPRAYED with acid from a 2 gallon jug, and could stealthily slip in his Sofnolime somehow (without melting the jug with the heat of the reaction or something), then yeah, I'm all for it being plausible. But there's just too much acid in a human-sized vat for it to make much difference.

DaveE