If My Hand Set On Fire, Would It Hurt?

I don’t actually remember where this question came from, or why my son asked it. I mean, I suspect it was inspired by playing a video game. Or maybe from watching cartoons. I just have “If my hand set on fire, would it hurt? How bad?” in my notes, with no context whatsoever.

That happens, sometimes. I’ve got a bunch of questions I jotted down, and many of them lack context. But, in this case, it makes a fun follow-up to my last article.

Sources of burns

To start answering his question, let’s start with how you can get burned. More things than just fire can burn you, after all – just ask your skin, after a day at the pool without sunscreen. In fact, the John Hopkins Medical Library provides four different sources of burns:

  • Thermal burns. These burns are due to heat sources which raise the temperature of the skin and tissues and cause tissue cell death or charring. Hot metals, scalding liquids, steam, and flames, when coming into contact with the skin, can cause thermal burns.
  • Radiation burns. These burns are due to prolonged exposure to ultraviolet rays of the sun, or to other sources of radiation such as X-ray.
  • Chemical burns. These burns are due to strong acids, alkalies, detergents, or solvents coming into contact with the skin or eyes.
  • Electrical burns. These burns are from electrical current, either alternating current (AC) or direct current (DC).

So, if my son’s hand was to be set on fire, he’d experience a thermal burn. Alternately, if he got a sunburn he’d have a radiation burn, if he poured lye on his hand he’d have a chemical burn, and if he stuck his finger in a live lightbulb socket he’d get an electrical burn. He’d also have parents doing their best to stay calm until he was taken care of, but that leads into an entirely different question of the “would you still love me if I did something stupid?” type.

(For the record, he’s never actually asked that question. But the answer is: “Yes, I would. I might not be happy with your behavior, but I’d still love you. Now take your fingers away from that electrical socket.”)

Ultimately, each of these sources of burns has some unique characteristics. But they all have the same basic effects.

Let’s talk about skin

Your skin has three layers: the epidermis, the dermis, and the hyodermis. The epidermis is the outer layer, composed of four to five layers of skin cells that protect the underlying layers. These cells manufacture and store keratin, a tough and fibrous protein that also (in a slightly different form) makes up our fingernails and hair and the horns of a rhinoceros. The epidermis also contains the skin pigment melanin, meaning that much of our conceptions of race aren’t even skin deep. The living layers of the epidermis are covered with layers of dead, keratinized cells that flake off over time. Beneath the epidermis is the dermis, two layers of connective tissue that contain blood and lymph vessels, nerves, hair follicles, sweat glands, and other structures. Finally, the hypodermis is connective tissue filled with more blood vessels and subcutaneous fat that serves to connect the skin to the bones and muscles.

“Solid burn, Branch.”

Returning to the John Hopkins Health Library, we learn that there are three classifications of burns – and you’ve probably heard what they are: first-degree, second-degree, and third-degree. Each of these relates to how deep the burn penetrates into the skin. First-degree burns are also referred to as superficial burns, and only affect the epidermis. It’ll be red and painful, dry to the touch, and lacking blisters.

Second-degree burns are also referred to as partial thickness burns, and both the epidermis and dermis are damaged. The skin will still appear read, but it is likely to be blistered and swollen.

Third-degree burns are also called full thickness burns, and this is where it gets really bad. The hypodermis is also damaged in a third-degree burn, and parts of the body below the hypodermis may also be involved. Parts like muscles, tendons, and bones (some sources call this a fourth-degree burn when this occurs). Third-degree burns will look whie or charred, and there tends to be no feeling in the burn site. Why? because the nerves have been destroyed.

Burns are further classified by burn percentage, which estimates the total area of the body affected by the burn. This is done on a “rule of nines”, in which body coverage is estimated in multiples of 9.

The chart doesn’t call out a hand specifically, but it would probably be considered 4.5%.

How much would it hurt?

There are a number of pain scales. The one I found first, and will be using as an example, ranks from 1-10 (well, technically 0-10, but 0 is “No pain. feeling perfectly normal.”). So, here’s the levels:

  1. Very light barely noticeable pain, like a mosquito bite or a poison ivy itch. Most of the time you never think about the pain.
  2. Minor pain, like lightly pinching the fold of skin between the thumb and first finger with the other hand, using the fingernails. Note that people react differently to this selftest
  3. Very noticeable pain, like an accidental cut, a blow to the nose causing a bloody nose, or a doctor giving you an injection. The pain is not so strong that you cannot get used to it. Eventually, most of the time you don’t notice the pain. You have adapted to it.
  4. Strong, deep pain, like an average toothache, the initial pain from a bee sting, or minor trauma to part of the body, such as stubbing your toe real hard. So strong you notice the pain all the time and cannot completely adapt. This pain level can be simulated by pinching the fold of skin between the thumb and first finger with the other hand, using the fingernails, and squeezing real hard. Note how the simulated pain is initially piercing but becomes dull after that.
  5. Strong, deep, piercing pain, such as a sprained ankle when you stand on it wrong or mild back pain. Not only do you notice the pain all the time, you are now so preoccupied with managing it that you normal lifestyle is curtailed. Temporary personality disorders are frequent.
  6. Strong, deep, piercing pain so strong it seems to partially dominate your senses, causing you to think somewhat unclearly. At this point you begin to have trouble holding a job or maintaining normal social relationships. Comparable to a bad non-migraine headache combined with several bee stings, or a bad back pain.
  7. Same as 6 except the pain completely dominates your senses, causing you to think unclearly about half the time. At this point you are effectively disabled and frequently cannot live alone. Comparable to an average migraine headache.
  8. Pain so intense you can no longer think clearly at all, and have often undergone severe personality change if the pain has been present for a long time. Suicide is frequently contemplated and sometimes tried. Comparable to childbirth or a real bad migraine headache.
  9. Pain so intense you cannot tolerate it and demand pain killers or surgery, no matter what the side effects or risk. If this doesn’t work, suicide is frequent since there is no more joy in life whatsoever. Comparable to throat cancer.
  10. Pain so intense you will go unconscious shortly. Most people have never experienced this level of pain. Those who have suffered a severe accident, such as a crushed hand, and lost consciousness as a result of the pain and not blood loss, have experienced level 10.

I couldn’t find any pain chart rankings for burn pain, partially because pain is a subjective (although real) phenomena. The Chicago Clinic explains, however, that

Burn pain can be one of the most intense and prolonged types of pain. Burn pain is difficult to control because of its unique characteristics, its changing patterns, and its various components. In addition, there is pain involved in the treatment of burns as the wounds must be cleansed and the dressings changed. Studies have concluded that the management of burn pain can be inadequate, and such studies have advocated more aggressive treatments for pain resulting from burns. Lastly, some burns can be mentally traumatic and/or physically disfiguring and lead to psychological pain that must be addressed, as well.

So there’s that.

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Can Metal Turn Into Fire?

The three of us – me, my wife, and my son – are on our way home from dinner yesterday, and my son’s been talking excitedly about a video game he got to play in a store.  “And then I knocked him into the water,” he announces, “and then I knocked him into the air, and then I won!  Daddy didn’t win a lot, though.”

“I made the mistake of trying to figure out what the buttons do,” I add.  “Our son just pushed things at random.  It’s nice to see that button-mashing is still a strategy.”

“Can metal turn into fire?” my son asks.

Eh?  Where did that come from?  My wife and I look at each other quizzically.  “It can melt,” she says, slowly.

“But can it turn into fire?”

“Do you mean ‘can it burn?'” I ask.

“Yeah!”

“I… think so?”

Can metal burn?

Brief answer: Yes. And in different colors.

Like I told my son, I think so.  Long ago, I was told that burning is just a special form of oxidation (aka “rusting”).  I don’t remember who told me that, or when, or why, so I don’t know that I can trust it.  Also, I vaguely recall that thermite is a metal that burns, and that titanium can burn.  So, yeah.  I’m utterly ignorant on the subject.

Let’s start with “burning”.

Conveniently, a while back I wrote an article titled “When Ice Is On Fire, Does The Ice Melt” where I discussed the concept of burning.  Here’s what I wrote:

Burning, more properly called a combustion reaction, is a little more complicated. There’s an entire subfield of chemistry called thermochemistry that deals with burning (or, more properly, the energy release from a combustion reaction). In general, though, you need a compound to combust and an oxidant to react with the combusting compound, and some energy to get it started. The oxidant and the combusting compound then combine in a chemical reaction to produce one or more new compounds, and since the reaction is exothermic the process of making the new compound(s) generates more energy than it gives off.

Yes, that does mean that once you get a combustion reaction started it will continue as long as it has combustible compounds and oxidants. That’s why fire spreads.

It turns out that I’d missed two important concepts when I wrote that article, though:  flash point and ignition temperature.  The flash point is the lowest temperature at which a combustable substance vaporizes into an ignitable gas, while the ignition temperature is the lowest point at which a combustable substance vaporizes into a gas that will self-ignite.  Note that word “combustable”, though.  Not every substance has a flash point or ignition temperature, because some substances (such as water and other combustion reaction products) are simply not combustable.

Look, we’ve been patient.  Can metal burn?

Well, some can.  If they’re combustible, which gets to the best definition I’ve seen in a long time:  “A combustible metal is defined as any metal composed of distinct particles or pieces, regardless of shape, size or chemical composition that will burn.”  Literally, a metal is defined as a metal that can burn if it is a metal that burns.  Although, in fairness, “burns” means “sustains ignition”.

The combustible metals that are :

And because I know you’re curious, here’s some sample solid metal ignition temperatures.  Bear in mind that, for comparison purposes, a Bic lighter can reach temperatures of 3,590.6 F (1,997 C):

  • Aluminum:  1,832 F (555 C)
  • Barium:  347 F (175 C)
  • Calcium: 1,300 F (704 C)
  • Iron: 1,706 F (930 C)
  • Lithium: 356 F (180 C)
  • Magnesium: 1,153 F (623 C)
  • Plutonium: 1,112 F (600 C)
  • Potassium: 156 F (69 C)
  • Sodium: 239 F (115 C)
  • Strontium: 1,328 F (720 C)
  • Thorium: 932 F (500 C)
  • Titanium: 2,900 F (1,593 C)
  • Uranium: 6,900 F (3,815 C)
  • Zinc: 1,652 F (900 C)
  • Zirconium: 2,552 F (1,400 C)

Hang on.  I have so many questions now.

Yeah, probably.  Let me anticipate them.

A metal doesn’t have to be a “combustible metal” to burn.  Any number of other metals will burn as well, but only as long as you apply heat.  Combustible metals, however, sustain burning even after the outside heat source is removed.  Aluminum will burn like a log, but copper will only burn as long as you apply sufficient heat.

Your pocket lighter will probably not set your cast iron skillet on fire, for the same reason that it will not set a log on fire.  A significant percentage of the object that you are trying to burn has to be heated to the flash point before it will catch fire.  You could probably set a super-thin iron wire on fire with a lighter, but you’d need a larger and sustained flame to ignite something big.

 

Oh, and here’s two more useful facts to know:

  • “Burning combustible metals can extract water from concrete, intensifying burning to cause spalling and explosion of the concrete.”
  • “Water applied to alkali metals will result in hazardous decomposition, ignition or explosion.  Alkali metals include lithium, sodium, potassium, cesium and francium.”

So, if you do manage to set your cheap fake diamond on fire?  Call a professional.

 

When Ice Is on Fire, Does The Ice Melt?

“Dad?”

“Yes, son?”

“When ice is on fire, does the ice melt?”

“…”

“…”

“…what?”

burning_ice_cube

It was one of those questions, the random sort of question a five-year-old (he just turned six last week, but he was five when he asked it) will ask. I don’t have any idea what prompted the question, or where it came from. But, the more I thought about it, the more interesting it sounded.

Can ice burn?

Well, it depends on what you mean by ‘ice’ and by ‘burn’. Here’s how Merriam-Webster defines it:

Full Definition of ice

  1. frozen water; a sheet or stretch of ice
  2. a substance resembling ice; especially : the solid state of a substance usually found as a gas or liquid <ammonia ice in the rings of Saturn
  3.  a state of coldness (as from formality or reserve)
  4. a frozen dessert containing a flavoring (as fruit juice); especially : one containing no milk or cream; British : a serving of ice cream
  5. slang : diamonds; broadly : jewelry
  6. an undercover premium paid to a theater employee for choice theater tickets
  7. methamphetamine in the form of crystals of its hydrochloride salt C10H15N‧HCI when used illicitly for smoking —called also crystal, crystal meth

For these purposes, we’ll stick with the first two definitions. ‘Frozen water’ and ‘the solid state of a substance usually found as gas or liquid’.

Burning, more properly called a combustion reaction, is a little more complicated. There’s an entire subfield of chemistry called thermochemistry that deals with burning (or, more properly, the energy release from a combustion reaction). In general, though, you need a compound to combust and an oxidant to react with the combusting compound, and some energy to get it started. The oxidant and the combusting compound then combine in a chemical reaction to produce one or more new compounds, and since the reaction is exothermic the process of making the new compound(s) generates more energy than it gives off.

Yes, that does mean that once you get a combustion reaction started it will continue as long as it has combustable compounds and oxidants. That’s why fire spreads.

So, can ice burn?

Water does not burn particularly well, because it’s already a product of a combustion reaction. Burning just about anything with hydrogen produces water. Burning hydrocarbon (sugar, wood, meat, alcohol, whatever) produces carbon dioxide and water and heat, burning hydrogen generates water and heat, burning acetylene gas forms carbon dioxide and water, and so on. Because it is the product of a combustion reaction, water is already at a low energy. You’d have to add energy (breaking the chemical bonds between the hydrogen and oxygen) to burn it, and then you’re not actually burning the water. You’re burning the hydrogen gas you released from the water.

Other ices can burn, however. Ethanol (a hydrocarbon) burns, and it freezes at -114 degrees Celsius (-173.2 degrees Fahrenheit). Gasoline (another hydrocarbon) certainly burns, and will freeze between -40 degrees and -60 degrees Celsius (-40 to -76 degrees Fahrenheit), depending on the exact properties of the substances in the gasoline. Acetone (nail polish remover) is another hydrocarbon, which freezes at -95 degrees Celsius (-139 degrees Fahrenheit) and which burns. Other liquids that burn also exist, obviously. And most of them require dangerously cold temperatures to freeze, and then will have fire. Use caution, lots of caution, if you actually plan to try this at home. And then, having exercised caution, you probably shouldn’t try this at home.

But, I really want burning water ice. For reasons.

Well, there’s a couple of different things you can do. The first is to put a layer of (water) ice cubes on top of a layer of calcium carbide. As the ice melts, the water reacts with the calcium carbide to produce hydrogen and acetylene gas, both of which will burn – old fashioned mining lamps actually used this reaction (something I learned when I went spelunking as a Boy Scout). The results look like this:

Another option is to pour alcohol on top of your ice, and light it up. The ice won’t burn, but there will be flames on the ice.

Regardless of which one of these you do, if you do one of them, please exercise caution. Lots of caution, because you’re playing with fire.

But… does the ice melt?

Yes. Because there is something hot near the ice, which will cause it to melt.