Physical chemistry in the kitchen

How do you use science outside of the lab?

People say that transferring knowledge and skills from one subject to another represents one of the highest levels of learning. They also say that it hardly ever happens. Perhaps this explains some of the more astounding things that we hear from Nobel Prize winners, like when Francis Crick proposed that Earth was settled by sperm from outer space, or when Watson, well, we'll leave that subject alone for now.

I admit, I don't always think to apply my scientific training to things that happen outside of the lab. When those moments do happen, I relish them. It's always good to feel that you have some permanent bit of knowledge from a class in physical chemistry.

Yesterday I got to trot it out and apply it in my kitchen.

Remember this: PV = nRT

I have used this relationship many times in the lab (every time I autoclave!), but it doesn't automatically come to mind when I'm cooking.

i-f89d85577584a35a40e9daef108e24b6-goldfinch-on_mustard.jpgWe have wild red mustard greens growing our backyard, as you see in this photo. I'm not a very diligent gardener. My garden mostly grows on it's own without any interference from me. The dog runs through it. Our three cats sleep in it. But my episodes of digging, planting, and harvesting are few and far between.

Still, there are lots of mustard greens growing wild in our back-yard. So I picked a whole bunch of them the other day and cooked them for dinner. Braised in home-made chicken broth with a bit of soy sauce, the mustard greens from the backyard are delicious.

I thought they were probably done, so I turned the heat off and let the cooking pot be while I helped set the table for the meal.

When all was ready, I lifted the cover of the pot. And, I lifted the entire pot off of the burner. The cover was stuck tight. I turned it. No luck.

i-1d521ada3667d81877bbd146502fd392-cooking_pot.jpgPuzzled, I stared at it a moment, wondering what to do and how we were going to eat my contribution to dinner.

Then my husband walked in. "Oh," he said, "Don't you remember? PV = nRT!"

"You need to heat it up and expand the gas."

Oh right, yeah, PV = nRT

(In words, this is pressure x volume = number of moles x a constant x temperature]

In other words, if I were to heat up the pot (increase the temperature, T), either the gas inside the pot would expand (increase in volume, V) or the pressure (P) inside the pot would increase and it would make it easier to take the top off.

Sure enough, it worked. I heated the pot and the lid came right off.

And the mustard greens were yummy, too.

More like this

Sperm from outer space? Oh, yeah, right, the Milky Way.

By Ken Shabby (not verified) on 04 Dec 2007 #permalink

People say that transferring knowledge and skills from one subject to another represents one of the highest levels of learning.
I like to say this as "If you can't play with [some subject], you haven't mastered it. If you don't play with [subject], you won't master it." "Play with it" here is intended to suggest the ability to find novel or unexpected ways to apply some field's knowledge, including mixing it with knowledge from other fields - i.e. "hacking".
I noticed that this works in the other direction too: I attribute the fact that I did so well in the Quantitative Analysis chemistry lab to my hobby of cooking. All those carefully honed "don't waste any of that flavor" reflexes meant that I was already tuned to watch for places where I might have to worry about losing bits of whatever I was analysing and how to keep as much of it as possible.
Panspermia (which doesn't literally mean "sperm cells") doesn't seem entirely implausible to me, but probably pretty unlikely. It also would only push back the question of life's origin one more step rather than really answering much ("it came from outer space" doesn't really explain how it got started...)

(oops, hit submit too soon)
An example of the "play with it" principle: "doing a Gram stain" is mere rote medical technology. Figuring out a way to infer that average amount of cell wall material in your bacterial culture based on the time it takes to "decolorize" the cells with a Gram-stain-like process is "playing with it"...
"Panspermia (which doesn't literally mean "sperm cells")[...]"
(*I* got the joke, incidentally, I just wasn't sure other people passing by and reading your post necessarily would...)

SMC: Most of the chemists that I know are pretty good cooks, except for the ones who damaged their noses by sniffing too much ammonia and too many other organics.

I have microbiology habits permanently ingrained in me. I can't open a tube of toothpaste without treating it like a culture tube. I absolutely, CANNOT let a jar remain open and uncovered on the counter. And, I've always had a hard time eating sushi, even though I only worked on parasites for a couple of years.

Good catch with the panspermia reference! I'm glad someone got it.

Cooking is how my mom taught me about chemistry and fractions. I loved learning why you could caramelize an onion- when caramels were clearly sticky candies wrapped in plastic.

And that's really all cooking is- chemistry that you eat. I suppose it's why I loved organic chem and love to cook.

Great blog, BTW.