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This question is about the old MacGyver show, Season 1, Episode 14, "Countdown." Could someone please explain how/why MacGyver neutralizes the acid in the bomb? He claims it is an electrolyte switch, and proceeds to neutralize it with oven cleaner and milk before draining it out.

  • wouldn't the milk act as a buffer?
  • wouldn't the neutralized solution also contain electrolytes?

Thanks!

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  • $\begingroup$ Can you present the relevant dialog from the episode? There isn't much to go on here. MacGyver sometimes had accurate science, but they never let accuracy get in the way of drama. $\endgroup$ – jeffB May 21 at 15:46
  • $\begingroup$ Some oven cleaners contain sodium hydroxide, which is a base $\endgroup$ – The_Vinz May 21 at 16:05
  • $\begingroup$ It is determined that the bomb has an "unstable electolyte fluid trigger," consisting of an acid solution. MacGyver: "The fluid carries a current. Now our problem is to neutralize it." $\endgroup$ – Rachel May 21 at 16:25
  • $\begingroup$ It is determined that the bomb has an "unstable electolyte fluid trigger," consisting of an acid solution, that if released, enters some wiring, creates a short, and sets off the bomb. MacGyver: "The fluid carries a current. Now our problem is to neutralize it." He mixes the oven cleaner and milk and injects it into the acid solution, which turns cloudy at first. Eventually the mixture turns clear, he drains it out, and shuts down power to the bomb. $\endgroup$ – Rachel May 21 at 16:32
  • $\begingroup$ Does he take a chug of milk first? Knowing McGyver he probably does. It's good for you: ansci.illinois.edu/static/ansc438/Milkcompsynth/… $\endgroup$ – Buck Thorn May 21 at 18:32
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The answer to your first question is yes, to the second maybe.

You are right that milk can act as a buffer, as explained for instance by this page from the Food Science Department of the University of Guelph:

This leads to the concept of buffer capacity, which is an important principle in cheese making. The effect of protein removal on the TA of whey, is related to the ability of protein to 'buffer' the milk against changes in pH. That same buffer property is the reason it helps to take acidic medication, like aspirin, with milk. [...] The two most important buffer components of milk are caseins (buffer maximum near pH 4.6) and phosphate (buffer maxima near pH 7.0). The buffer maximum near pH 5.0 is extremely important to cheese manufacture because the optimum pH for most cheese is in the range of 5.0 - 5.2. As the pH of cheese is reduced towards pH 5.0 by lactic acid fermentation, the buffer capacity is increasing (i.e., each incremental decrease in pH requires more lactic acid). The effect is to give the cheese maker considerable room for variation in the rate and amount of acid production. Without milk's built in buffers it would be impossible to produce cheese in the optimum pH range.

On the other hand denaturation of the milk proteins might act to form a gel that could perhaps help stabilize the trigger fluid, but milk gelation appears to display a complex pH dependence and a mechanism of stabilization is unclear.

The electrolyte concentration might be diluted by milk, since its ionic strength is surprisingly moderate, see Ref (1) for instance:

Taking into account these different associations, the diffusible fraction of milk at pH 6.6–6.7 appears to be supersaturated in calcium phosphate (Tab. V), and to have an ionic strength of about 80 mM.

Much of the salt is bound to protein which forms part of the buffering system. So much depends on the composition of the sinister trigger fluid.

The substantial concentration of divalent calcium (~1 g/L or ~50 mM) might be useful, but how will presumably also remain a well-kept secret of the writers privy to the composition of the very unstable trigger electrolyte fluid.

Reference

  1. Frédéric Gaucheron. The minerals of milk. Reproduction Nutrition Development, EDP Sciences,2005, 45 (4), pp.473-483.
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