ice solid vs liquid
Don Guthrie
My son is doing a science project and one of his questions is if ice weighs
4 oz when frozen, will it weigh 4 oz when it is thawed? why or why not?
Please help or give me some ideas as to where I can look this up. Please
send me an email to
THANKS!!!
Dr. Kenneth R. Metz
When 4 oz of ice melts, it does indeed form 4 oz of water. This is a
principle known as conservation of mass, and it is fundamental to most
of chemistry. The principle is only violated in extremely rare
instances such as conversion of mass to energy during a nuclear
explosion. In chemistry, the assumption is always that total mass is
conserved during any chemical reaction or physical state conversion
(i.e., solid-to-liquid, liquid-to-gas, etc).
Note that while the mass of ice and the water it forms are identical,
their volumes are not. Water is one of the few materials that
actually expands to occupy a slightly larger volume when it freezes.
Thus, the density (mass per unit volume) of ice is smaller than liquid
water, and ice cubes float in a glass of water.
These issues should be dealt with in any good junior high general
science text, and will certainly be discussed in high-school (or more
advanced) chemistry texts.
Hope this helps.
Alan "Uncle Al" Schwartz
"Don Guthrie" <dgut...@cerner.com> wrote:
>My son is doing a science project and one of his questions is if ice weighs
>4 oz when frozen, will it weigh 4 oz when it is thawed? why or why not?
>Please help or give me some ideas as to where I can look this up. Please
>send me an email to
First Law of Thermodynamics: You cannot win (conservation of mass/energy)
Second Law of Thermodynamics: You can only break even on a very cold day
(Carnot efficiency).
Third Law of Thermodynamics: It never gets that cold.
For each gram of water at 0 C converted to ice at 0 C, you must remove 80
calories of energy. For each degree C above the melting point, each
degree of temperature increase requires addition of another calorie/gram.
One weight ounce is 28.35 grams of water. Starting with 4 oz water at 20
C and cooling to 0 C you will remove 11.34 Kcal of energy, or 47.47
Joules of energy. A kiloton of energy, 4.18x10^12 Joules, weighs 44.51
milligrams. Figure out how much the ice changes in mass.
Within experimental error, the weight of the water does not change.
--
Alan "Uncle Al" Schwartz
Uncl...@ix.netcom.com ("zero" before @)
http://www.ultra.net.au/~wisby/uncleal.htm
(Toxic URL! Unsafe for children, Democrats, and most mammals)
"Quis custodiet ipsos custodes?" The Net!
William Wu
Don Guthrie <dgut...@cerner.com> wrote:
: My son is doing a science project and one of his questions is if ice weighs
: 4 oz when frozen, will it weigh 4 oz when it is thawed? why or why not?
: Please help or give me some ideas as to where I can look this up. Please
: send me an email to
Assuming no evoporation losses, the mass will be the same. (Mass is always
conserved). And basic chem or Physics books at your local libarary will
have the reasons.
--
William C. Wu <gan...@phantom.us.com>
PGP Key ID = 16BD27AD 'finger -l gan...@rahul.net' for public key
Key Fingerprint = 76 7E 2B 8A 41 96 08 FB 6E 0D B6 48 55 4E 0F 6E