Question about melting lead....

[DrNick]

Okay...

I have wondered about this for a while....

A BTU is the amount of energyit takes to heat one pound of water one degree F. Given that lead is 11 times more dense than water does it mean that it takes 11 time as many BTUs to heat a pound of lead the same amount?

Somehow that doesn't make sense....

My Coleman stove will boil a pot of water in a few minutes....it deosn't take THAT much longer to melt WW...may 15-20 minutes but the WW weigh more.

Any ideas?

[runfiverun]

lead holds heat better than water does.
you warm up 8.3 lbs per gallon of water, a gallon sized chunk of lead is more like 250 lbs.

[shaune509]

As per CRC chemistry #57 handbook. 1977
BTU = average heat required to raise 1# H2O 1deg from 32 to 212 F or 1# 1 deg @ 60F = 1.0003601BTU's [not linar in value]
Specific Heat is thermal capacity ratio of substance to water @15C
Specific heats of Aluminum=0.215
Antimony=0.049
Copper=0.092
Iron=0.106
Lead=0.038
Tin=0.051/0.053
Zinc=0.0928
values as per Bureau of Mines #592 [1961]
Hope this helps shed some light on this complex issue.
shaune509

[Ole]

Water is very good at holding heat, better than anything I can think of offhand.

Our weather would be a lot worse in most of the Earth if the oceans weren't shipping warmth all around the globe like they do all the time.

If you submerged 11lbs of molten lead in 11lbs of water the lead would quickly assume the water's temperature + a few degrees.

[uscra112]

In metric units, water in the liquid phase takes about 4.18 Joules per gram per degree Celsius, while lead in the solid phase takes only .129 Joules. I did not find a value for lead in the liquid phase, nor did I find a number for the energy required to change phase from solid to liquid for lead. But pound for pound, lead takes a lot less heat. Per unit of VOLUME, the ratio is water=4.2 and lead = 1.44. Either way, it's much easier to heat lead than water.

[bumpo628]

Water has much better contact with the pot since it is already liquid.
WW's are lumpy and only touch the pot in spots, so the heat transfer is not as efficient.
That makes comparing them that much more complicated.

[DeadWoodDan]

This is the equation your looking for.

Q=energy gained(+) or lossed(-) normally measured in cal. (NOT Calories capital "C")
m= mass of material
c= specific heat of materials exp. water = 1cal/g degree Celcius
Tf= final temp.
Ti= initial temp.
Tf-Ti also = delta T = change in temperature

Will have to go over notes but you may also have to add/subtract any energy given off because of Laten Heat.

using the above you can then convert cal into BTU's

DWD



Okay...

I have wondered about this for a while....

A BTU is the amount of energyit takes to heat one pound of water one degree F. Given that lead is 11 times more dense than water does it mean that it takes 11 time as many BTUs to heat a pound of lead the same amount?

Somehow that doesn't make sense....

My Coleman stove will boil a pot of water in a few minutes....it deosn't take THAT much longer to melt WW...may 15-20 minutes but the WW weigh more.

Any ideas?