Physics Van 3-site Navigational Menu

Physics Van Navigational Menu

Q & A: Why does ice melt faster in tap water than in salt water?

Learn more physics!

Most recent answer: 07/27/2013
Q:
Hi, your answer for why ice melts faster in salt water vs. tap water is not correct. It does have to do with density, but not in how high something floats. Try the experiment with one normal ice cube and one colored ice cube, both in salt water and in tap water. You will find the results interesting.
the best android phone link phone tracking apps
married men cheat with men why husbands cheat wifes cheat
types of abortions read what happens when you get an abortion
free prescription cards nwwebdesigns.net walgreens prints coupon codes
rite aid prescription transfer coupon mesutcakir.com.tr coupon rite aid
levitra pill go tadalafil pill
prescription drugs discount cards link coupons for viagra printable
viagra coupon card blog.brunothalmann.com viagra free coupon
viagra coupons free read drug coupons
pfizer coupons for viagra prescription coupon viagra discounts coupons
coupons prescriptions blog.brunothalmann.com manufacturer coupons for prescription drugs
discount prescriptions coupons mba-institutes.com internet drug coupons
can i take minocycline with birth control read can i take minocycline with birth control
where buy viagra online viagra for sale uk online viagra buy
discount prescription drug cards nationalautocare.com prescription discounts cards
voltaren ára voltaren duo voltaren
arcoxia 30 click arcoxia wiki
flibanserin online click flibanserin buy
cialis cialis cialis walgreen coupon
fluvoxamine (luvox) open fluvoxamina bula
buscopan hund buscopan wirkung buscopan dragees
cefdinir red stool ski-club-auringen.de cefdinir nedir
renovacija stanovanja renovator renova g
lasix injetavel lasix lasix
nurofen cold and flu dosage internetsellout.com nurofen plus dosage
prescriptions coupons emergent-ventures.com drug prescription card
trental cena trental trental nuspojave

- Greg Baxley (age 31)
Bakersfield College, CA
A:
Greg -

Thank you for your correction! We have removed the original answer from our database.

It is true that an ice cube will melt much faster in tap water than in salt water. And although there is a difference in how high the ice cube will float in each (as I’d said before), it is not enough to make the major difference.

When you think of a regular ice cube melting in a regular glass of water, you have to remember that cold water (like the water from the ice cube) is actually denser than warm water (like the water in the cup). This is because in the cold water, the molecules have less energy and are actually closer together than in warmer water. So as the ice cube melts, the cold water coming off of it sinks to the bottom of the glass and the warm water from the bottom comes up to take its place. The water in the glass is actually constantly moving, keeping the ice cube warm by something that scientists call ’convection currents.’

But salt water is much denser than tap water, warm or cold. So when you put a freshwater ice cube in a glass of salt water, the cold water coming off the ice cube doesn’t sink at all. Instead, the dense salt water stays at the bottom of the glass and the cold water stays on the top. Without any convection currents to carry the cold water away from the ice cube, the ice cube melts much more slowly.

Thank you again for this correction... please feel free to let us know if you see any other errors on our page.

-Tamara

If you’re interested in finding more information on experiments to use in your class on the role of convection in melting ice, you can also check out this article: ’Denison, R.F. Agricultural physics: a laboratory mystery to learn about convection. Golden Slate (Calif. Agric. Teachers’ Assoc. newsletter), March, 1999.’ (Submitted by Ford Denison, Age 47 from UC Davis.)
cheater what to do when husband cheats wifes who cheat
cheater click wifes who cheat
internet drug coupons coupons for prescription medications prescription coupon
married men cheat with men open wifes cheat
types of abortions read what happens when you get an abortion
types of abortions site what happens when you get an abortion
cvs discount card cvs coupon online prescription drugs discount cards
married cheaters site dating for married men
discount card prescription damske.com print cvs
coupons for prescriptions floridafriendlyplants.com prescription drugs discount cards
pfizer coupons for viagra prescription coupon viagra discounts coupons
coupons prescriptions blog.brunothalmann.com manufacturer coupons for prescription drugs
1 wk pregnant d&c dilation and curettage article on abortion
lisinopril and energy drinks lisinopril and energy drinks lisinopril and energy drinks
viagra bestellen online viagra pillen kruidvat pillen kopen
cialis price online lipseysguns.com cialis price history
cialis coupons from lilly coupon for free cialis coupons for prescriptions
coupons for prescriptions discount prescription coupons drug prescription card
augmentin générique arbot.cz augmentin sirop
arcoxia 30 go arcoxia wiki
champix alkohol click champix
flibanserin online flibanserin buy flibanserin buy
voltaren retard voltaren pomada voltaren spray
vivitrol alcohol naltrexone alcoholism medication narcan challenge

(published on 10/22/2007)

Follow-Up #1: salt and melting ice

Q:
The answer you give (below) is also incorrect. When you put a freshwater ice cube in a glass of water, it melts faster, not slower! Thats why they use ice to melt snow off roads. The reason has little if anything to do with convection currents, as is demonstrated by the effect of sprinkling dry salt on to the top of an ice cube... you can see the ice cube melt away before your eyes, much more rapidly than an unsprinkled ice cube. The reason has to do with the effect of the salt molecules on the vibration of the water molecules, in the liquid salt solution and the solid freshwater. At the interface, an equilibrium is established between ice and water - water is constantly freezing and melting, so molecules are moving back and forth between the states. The ratio of the speeds of freezing and melting, (which at the molecular level is a change in vibration speed)determines whether the overall trend is towards liquid or solid. This equilibrium is changed by the presence of an impurity in the liquid, but not the solid, so the ratio is changed, hence the overall melting rate changes. This is only a short summary of a fairly complex phenomena, the maths of which is quite involved. "But salt water is much denser than tap water, warm or cold. So when you put a freshwater ice cube in a glass of salt water, the cold water coming off the ice cube doesn’t sink at all. Instead, the dense salt water stays at the bottom of the glass and the cold water stays on the top. Without any convection currents to carry the cold water away from the ice cube, the ice cube melts much more slowly. "
the best android phone link phone tracking apps
cvs discount card cvs new prescription coupon prescription drugs discount cards
abortion pill clinics abortion pill prices for abortions
discount card prescription damske.com print cvs
rite aid prescription transfer coupon open coupon rite aid
prescription drugs discount cards link coupons for viagra printable
coupons prescriptions blog.brunothalmann.com manufacturer coupons for prescription drugs
discount prescriptions coupons pet prescription discount card internet drug coupons
viagra bestellen online viagra pillen kruidvat pillen kopen
where buy viagra online viagra for sale uk online viagra buy
cialis price online open cialis price history
cialis coupon lilly click transfer prescription coupon
cialis coupon card open cialis coupons from manufacturer
drug discount coupons blog.suntekusa.com discount coupons for prescriptions
drug discount coupons blog.suntekusa.com discount coupons for prescriptions
coupons for prescriptions mha.dk drug prescription card
lilly cialis coupon click coupons prescriptions
voltaren ára house.raupes.net voltaren
venlafaxine gewichtstoename idippedut.dk venlafaxine fk
ibuprofen rapid ibuprofen spc ibuprofen
lasix injetavel lasix efeitos colaterais lasix
lasix injetavel lasix lasix
prescriptions coupons coupons for prescriptions drug prescription card
trental cena link trental nuspojave

- Marcus (age 41)
Australia
A:
Marcus- You have confused two things. The first is the effect of salt on the melting temperature of ice and the second is the rate at which a (melted) equilibrium is reached. There is no doubt at all that salt lowers the freezing point of water. So does any stable solute which doesn't freeze into the ice. One can prove that rigorously via a thermodynamic argument. That's why salt is used to melt snow.
    By the way, the main reason for the lowering of the freezing point by solutes is the effect of the changing liquid volume on the entropy of the solute. This effect is rather easy to calculate, and turns out to agree well with the observed effects.  Other effects can matter at higher solute concentrations, and can either increase or decrease the lowering of the freezing point.

The second point concerns the rate at which ice will melt to liquid in a glass of salty or pure water. Rates are much more complicated things than thermodynamic equilibria, and it turns out that in this case the actual effect is typically as described in our old answer.

Mike W.
cheater click wifes who cheat
cheater read wifes who cheat
the best android phone mealmixer.com phone tracking apps
cvs discount card cvs new prescription coupon prescription drugs discount cards
online discount pharmacy dotnetblogengine.net coupon for prescription
viagra coupon card free prescription cards discount viagra free coupon
coupon for viagra viagra trial coupon viagra discount coupons online
cialis dosage and go cialis dose for copd pts
acheter viagra pas acheter viagra pas acheter viagra pas
cialis manufacturer coupon link prescription drug coupons
cialis manufacturer coupon link prescription drug coupons
coupons for prescriptions discount prescription coupons drug prescription card
lilly cialis coupon coupons for prescriptions coupons prescriptions
naprosyn roche rileytech.net naprosyn nedir
niacine movidafm.net niacin v hrani
kamagra wikipedia kamagra jelly kamagra shop
fluvoxamine (luvox) open fluvoxamina bula
cialis cialis discount cialis walgreen coupon
cefdinir red stool cefdinir nedir cefdinir nedir
cefdinir red stool ski-club-auringen.de cefdinir nedir
voltaren retard link voltaren spray

(published on 03/27/2008)

Follow-Up #2: cooling ice with salt

Q:
Does the addition of salt to ice actually make the ice warmer or just lowers the melting point, which would make it really cold water?
cheater click wifes who cheat
married woman looking to cheat My wife cheated on me most women cheat
types of abortions the weeks of pregnancy what happens when you get an abortion
walgreens coupons deals free grocery coupons walgreens photo print coupons
buy sildenafil 100mg buy sildenafil 100mg viagra 100 mg
priligy 30mg click cialis 40mg
levaquin pill diprolene 0.05% furosemide pill
prescription drugs discount cards blog.plazacutlery.com coupons for viagra printable
viagra coupons from manufacturer liberitutti.info drug discount coupons
coupons for prescriptions floridafriendlyplants.com prescription drugs discount cards
coupons prescriptions blog.brunothalmann.com manufacturer coupons for prescription drugs
lisinopril and bisoprolol lisinopriland.net lisinopril and bisoprolol
drug discount coupons blog.suntekusa.com discount coupons for prescriptions
champix alkohol go champix
champix alkohol go champix
fusidinezuur kopen fusidinezuur kopen fusidic acid
niacine movidafm.net niacin v hrani
ibuprofen rapid tracyawheeler.com ibuprofen
cialis cialis discount cialis walgreen coupon
renovacija stanovanja click renova g
prescriptions coupons coupons for prescriptions drug prescription card

- Jeff
New Jersey
A:
The presence of salt lowers the melting point, as we discuss elsewhere. Unless the ice is very cold, some of it will then melt. The liquid state has higher energy density than the frozen state, so that energy has to come from the thermal jiggles in the ice and salt. They will actually cool down as they melt, although gradually heat will leak in from elsewhere.

Incidentally, adding ordinary table salt (NaCl) to liquid water soaks up some enthalpy, so if the salt and water started at the same temperature, they get cooled a bit by forming a solution. Some other salts release some heat as they dissolve.

Mike W.
why people cheat marriage affairs how many people cheat
hillcrest abortion clinic abortive live abortion video
hillcrest abortion clinic abortive live abortion video
best android spy spy on mobile how to spy on an android phone
free prescription cards nwwebdesigns.net walgreens prints coupon codes
coupons rx prostudiousa.com www.januvia.com coupons
coupons for prescriptions new prescription coupons prescription drugs discount cards
viagra coupons free softballspa.com drug coupons
pfizer coupons for viagra viagra coupon viagra discounts coupons
acheter viagra pas acheter viagra pas acheter viagra pas
cialis price online link cialis price history
cialis manufacturer coupon link prescription drug coupons
voltaren ára go voltaren
venlafaxine gewichtstoename read venlafaxine fk
kamagra wikipedia kamagra jelly kamagra shop
fluvoxamine (luvox) open fluvoxamina bula
cefdinir red stool ski-club-auringen.de cefdinir nedir
nurofen cold and flu dosage internetsellout.com nurofen plus dosage
motilium enceinte motilium notice motilium et grossesse
trental cena trenitalia trental nuspojave

(published on 05/16/2013)

Follow-Up #3: salt water freezing again

Q:
Ok. all you little kids are wrong! I did a big huge project on this and i won 1st place in the science fair. If you put water and ice together in a cup and a cup of just water in the freezer at the same time then the one with salt will freeze faster. This happens because when salts solute in water they break apart as ions for example table salt, NaCl, becomes Na+(aq) Cl-(aq) water, which is already somewhat polarizes, reacts to the soluted ions by polarizing further, thus making the bonds between water molecules more powerful stronger bonds means more it takes more energy to keep them apart, means they'll solidify at a higher temperature. So yeah u little kids dont know anything bout this stuff. well mmmkay have a good day! XD
why people cheat marriage affairs how many people cheat
cheater what to do when husband cheats wifes who cheat
the best android phone mealmixer.com phone tracking apps
diprolene site furosemide 40mg
levaquin pill cephalexin 250mg furosemide pill
levitra pill mostefaiamine.com tadalafil pill
viagra coupons free softballspa.com drug coupons
pfizer coupons for viagra viagra coupon viagra discounts coupons
pfizer coupons for viagra viagra coupon viagra discounts coupons
discount prescriptions coupons mba-institutes.com internet drug coupons
can i take escitalopram in the morning can i take escitalopram in the morning can i take escitalopram in the morning
lisinopril and energy drinks lisinopril and energy drinks lisinopril and energy drinks
acheter viagra pas acheter viagra pas acheter viagra pas
acheter viagra pas acheter viagra pas acheter viagra pas
prescription drug coupons prescription discount coupon drug coupon
drug discount coupons link discount coupons for prescriptions
discount prescription drug cards cialis online coupon prescription discounts cards
naproxennatrium zygonie.com naproxen migraine
venlafaxine gewichtstoename read venlafaxine fk
renovacija stanovanja blog.myexpensesonline.co.uk renova g
nurofen cold and flu dosage internetsellout.com nurofen plus dosage
trental cena link trental nuspojave
vivitrol alcohol vivitrol implant narcan challenge

- Binky (age 15)
california
A:
Wow, where to start? 

First, I assume that by "water and ice" you meant "water and salt", otherwise it doesn't connect with the rest of your discussion.

Let's start with the obvious parts based on familiar facts.

If salt tended to stabilize ice more than water, by the fancy mechanism you describe, adding salt to ice would help keep it frozen. Somebody better tell the Highway Department, because they've been using salt to melt ice all these years.

Working our way toward slightly less familiar facts, the mechanism you describe would only work if the salt was actually in the ice, helping line up those water molecules. However, virtually none of the salt goes in to the ice. You can check this by partially freezing some salt water. You'll find that the non-frozen liquid is saltier than what you started with, because salt was excluded from the ice.

I'm trying to see if there is any grain of truth in what you've written. It is true that dissolving table salt in water will lower the temperature of the water, because it takes energy (more precisely, enthalpy) to pull those ions apart. That could help freeze the water. However, that effect amounts to only about 0.9 K cooling for 1 M salt concentration. (That cooling is temporary and has no effect on the freezing time for the salt water if you let it stand at room temperature before putting it in the freezer.) The same 1M NaCl lowers the freezing point of water by about 3.7 K, so it still needs to cool more than plain water before it freezes, even if you didn't let it reach room temperature first.

So I have to conclude that everything you wrote about the science of water and salt is incorrect.

Is it possible that your glass  of salt water froze first? Maybe- freezers don't cool evenly, some spots already have frost, some are in good contact with metal, so it takes a lot of care to check whether the result depended on details of placement, etc. However if you got the water really salty, stirring in NaCl until no more would dissolve, the water wouldn't freeze until it was cooled to -21.1 °C. Ordinary home freezers don't usually get quite that cold, so unless you have a very good freezer on the coldest setting you would never have seen it freeze.

For anybody who wonders who is right: do the experiment yourself.

Mike W.
the best android phone how to spy on cell phones phone tracking apps
internet drug coupons coupons for prescription medications prescription coupon
types of abortions the weeks of pregnancy what happens when you get an abortion
best android spy open how to spy on an android phone
abortion pill clinics abortion pill prices for abortions
walgreens coupons deals free grocery coupons walgreens photo print coupons
diprolene kamagra furosemide 40mg
coupons rx prostudiousa.com www.januvia.com coupons
ventolin 2mg bistromc.org deltasone 40mg
prescriptions coupons discount card for prescription drugs discount coupon for viagra
viagra coupons from manufacturer open drug discount coupons
new prescription coupon areta.se prescription coupon card
diabetes affect sexuality cialis dosage information diabetes sexuality treatment
acheter viagra pas acheter viagra pas acheter viagra pas
cialis manufacturer coupon cialis discounts coupons prescription drug coupons
lilly cialis coupon prostudiousa.com coupons prescriptions
augmentin générique arbot.cz augmentin sirop
arcoxia 30 click arcoxia wiki
ibuprofen rapid tracyawheeler.com ibuprofen
sildenafil pfizer link sildenafil sandoz
lasix injetavel lasix lasix
nurofen cold and flu dosage internetsellout.com nurofen plus dosage
nurofen cold and flu dosage internetsellout.com nurofen plus dosage
prescriptions coupons cialis coupon drug prescription card
vivitrol alcohol naltrexone alcoholism medication narcan challenge

(published on 09/11/2009)

Follow-Up #4: experiments on melting ice

Q:
We do an experiment in my online chem class where we put food coloring into water and then freeze it. Then we put the colored ice into tap water (fresh water) and water with either salt or sugar in it. The tap water melts the cubes in about half the time as the salt/sugar water. It is a matter of bringing warm water into contact with the surface of the cube (this happens with the tap water because of convection) and layering of the cold, colored melt on top of the denser solution (little convection of the bulk fluid here). We also use the layers on top of the solutions to test diffusion--which turns out to be both surprisingly slow (takes several days on the counter top and over a week in the refrigerator) and smooth. Most of the time diffusion measurements are confused by convection but these don't seem to be bothered. The nice thing about using the color is that you can see the currents (and lack of currents) and you can add the diffusion activity. Tall thin (parfait) glasses work best for both parts of the experiment.
why people cheat catch a cheat how many people cheat
the best android phone how to spy on cell phones phone tracking apps
married woman looking to cheat married men that cheat most women cheat
types of abortions site what happens when you get an abortion
buy sildenafil 100mg viagra without a doctor prescription viagra 100 mg
viagra coupons from manufacturer liberitutti.info drug discount coupons
manufacturer coupons for prescription drugs viagra 2016 coupon coupon prescription
can i take antabuse and naltrexone can i take antabuse and naltrexone can i take antabuse and naltrexone
lisinopril and bisoprolol lisinopriland.net lisinopril and bisoprolol
cialis price online link cialis price history
cialis coupon lilly blog.nvcoin.com transfer prescription coupon
prescription drug coupons cialis coupons from lilly drug coupon
drug discount coupons link discount coupons for prescriptions
diflucan 150 gruene-kehl.de diflucan sirup
flibanserin online lasertech.com flibanserin buy
sildenafil pfizer link sildenafil sandoz
seroquel 25 mg site seroquel debljanje
allods online cwblog.centralworld.co.th allo allo

- Bennett Willis (age 68)
Lake Jackson, TX, USA
A:
Thanks, I bet some  of our other readers will want to use this technique.

I wonder if we can use the technique to demonstrate diffusion in class. Our other diffusion demos are messed up by convection, as you say. The issue will be if we can get the apparatus to sit untouched for a few days between classes.

Mike W.
internet drug coupons coupons for prescription medications prescription coupon
married men cheat with men why husbands cheat wifes cheat
rite aid prescription transfer coupon open coupon rite aid
ventolin 2mg thyroxine 25mcg deltasone 40mg
free online coupons pharmacy coupon new prescription coupons
online discount pharmacy dotnetblogengine.net coupon for prescription
coupon for viagra modelosguayaquil.com viagra discount coupons online
cialis dosage and go cialis dose for copd pts
diabetes affect sexuality open diabetes sexuality treatment
lilly cialis coupon coupons for prescriptions coupons prescriptions
naproxennatrium click naproxen migraine
diflucan 150 site diflucan sirup
proscar vs propecia for hair loss proscar pris proscar pris
fluvoxamine (luvox) open fluvoxamina bula
cialis open cialis walgreen coupon
cefdinir red stool cefdinir nedir cefdinir nedir
nurofen cold and flu dosage internetsellout.com nurofen plus dosage
allods online cwblog.centralworld.co.th allo allo
cialis coupon card coupon prescription cialis coupon

(published on 09/15/2009)

Follow-Up #5: stirred salt water and ice

Q:
What if your two glasses of salt and fresh water were constantly stirred? Would the ice melt faster in the salt water? That would eliminate the density stratification that you described that causes the cold water to stay on top of the salt solution.
married woman looking to cheat go most women cheat
cvs discount card cvs new prescription coupon prescription drugs discount cards
married cheaters site dating for married men
priligy 30mg click cialis 40mg
prescription drugs discount cards link coupons for viagra printable
viagra coupons from manufacturer liberitutti.info drug discount coupons
prescription drugs coupons viagra manufacturer coupon 2016 viagra coupon card
coupon for viagra modelosguayaquil.com viagra discount coupons online
can i take escitalopram in the morning can i take escitalopram in the morning can i take escitalopram in the morning
can i take minocycline with birth control can i take minocycline with birth control can i take minocycline with birth control
lisinopril and energy drinks lisinopril and energy drinks lisinopril and energy drinks
acheter viagra pas acheter viagra pas acheter viagra pas
where buy viagra online http://viagraforsaleuk1.com online viagra buy
naproxennatrium zygonie.com naproxen migraine
voltaren ára voltaren duo voltaren
venlafaxine gewichtstoename idippedut.dk venlafaxine fk
arcoxia 30 arcoxia 90 arcoxia wiki
fusidinezuur kopen go fusidic acid
diflucan 150 diflucan djelovanje diflucan sirup
flibanserin online lasertech.com flibanserin buy
sildenafil pfizer dotnetblogengine.net sildenafil sandoz
proscar vs propecia for hair loss proscar pris proscar pris
seroquel 25 mg read seroquel debljanje
renovacija stanovanja click renova g
lasix injetavel lasix para emagrecer lasix
cialis coupon card evans.com.mx cialis coupon
prescriptions coupons cialis coupon drug prescription card
trental cena link trental nuspojave
how expensive is an abortion do abortions hurt abortion clinics dallas tx

- James M (age 60)
Austin, TX
A:
The best way to tell is by experiment, but I'd lay good odds that you're right.

Mike W.
why people cheat marriage affairs how many people cheat
hillcrest abortion clinic stories of abortion live abortion video
internet drug coupons open prescription coupon
levaquin pill internetsellout.com furosemide pill
finasteride lasix 40mg cialis 80mg
finasteride sigridw.com cialis 80mg
online discount pharmacy viagra coupons and discounts coupon for prescription
viagra coupons from manufacturer liberitutti.info drug discount coupons
coupons for prescriptions mha.dk drug prescription card
discount prescription drug cards nationalautocare.com prescription discounts cards
naproxennatrium zygonie.com naproxen migraine
niacine movidafm.net niacin v hrani
diflucan 150 diflucan djelovanje diflucan sirup
proscar vs propecia for hair loss proscar pris proscar pris
cefdinir red stool ski-club-auringen.de cefdinir nedir
renovacija stanovanja renovator renova g
motilium enceinte motilium notice motilium et grossesse
cialis coupon card evans.com.mx cialis coupon
cialis coupon card evans.com.mx cialis coupon
how expensive is an abortion abortion clinic abortion clinics dallas tx

(published on 11/05/2009)

Follow-Up #6: ice melting with salt or not

Q:
I read the discussion on ice melting in tap water vs. ice melting in salt water and I also researched other websites and I am confused. My 4th grader and I tested ice cubes melting in glasses of tap water vs. salt water, sugar water and baking soda water and found that by adding the various solutes we indeed saw a temprature drop of the water. We also observed that an ice cube in tap water melted at a much faster rate and the baking soda/ water cube melted the slowest. We then took ice cubes and placed them on individual plates. We sprinkled one cube with salt and left the other alone. We covered the cubes with glasses and observed that the cube sprinkled with salt melted faster. To me the results were confusing. Is this two different things taking place?
cheater click wifes who cheat
hillcrest abortion clinic site live abortion video
diprolene kamagra furosemide 40mg
levitra pill imitrex 25mg tadalafil pill
viagra coupons from manufacturer liberitutti.info drug discount coupons
discount prescriptions coupons pet prescription discount card internet drug coupons
1 wk pregnant abortion pill article on abortion
can i take antabuse and naltrexone can i take antabuse and naltrexone can i take antabuse and naltrexone
cialis dosage and cialis dose for copd pts
diabetes affect sexuality open diabetes sexuality treatment
cialis manufacturer coupon cialis discounts coupons prescription drug coupons
cialis coupon lilly blog.nvcoin.com transfer prescription coupon
champix alkohol mdwguide.com champix
proscar vs propecia for hair loss proscar pris proscar pris
renovacija stanovanja renovator renova g
cialis coupon card coupon prescription cialis coupon

- Jim Houghtaling
Lancaster, SC 29720
A:
If I understand your descriptions right, what you saw fits pretty well with our old explanations. In a salty liquid, the melting is actually slowed down, because the cold melted water sits on top of the denser salty water. That keeps heat from getting quickly to the ice. On the other hand, direct contact with salt promotes melting.  Furthermore, actual dissolving of salt in water soaks up some energy and cools things down.  So yes, several effects are present, and what you saw fits expectations very well.

Mike W.
cheater click wifes who cheat
hillcrest abortion clinic site live abortion video
the best android phone link phone tracking apps
cvs discount card cvs new prescription coupon prescription drugs discount cards
abortion pill clinics abortion pill prices for abortions
imitrex 50mg thyroxine flagyl 200mg
cialis dosage and cialis dose for copd pts
where buy viagra online http://viagraforsaleuk1.com online viagra buy
cialis coupons from lilly coupon for free cialis coupons for prescriptions
cialis manufacturer coupon link prescription drug coupons
cialis coupon lilly click transfer prescription coupon
lilly cialis coupon prostudiousa.com coupons prescriptions
proscar vs propecia for hair loss proscar pris proscar pris
seroquel 25 mg site seroquel debljanje
cialis cialis discount cialis walgreen coupon
buscopan hund buscopan dosierung buscopan dragees
motilium enceinte blog.cr-inside.org motilium et grossesse
how expensive is an abortion do abortions hurt abortion clinics dallas tx

(published on 03/04/2010)

Follow-Up #7: disputes about melting of ice by salt

Q:
It is my understanding that a solute, such as salt (NaCl) melts ice not by the process listed above but by one slightly different. In this process, the salt ionizes at the surface of the ice where an equilibrium between ice and water exists. The salt ionizes into Na+ and Cl- within the water at the surface (NOT the ice). Thus this water at the surface has solutes in the solution and a lower freezing point than the water originally on the surface, and consequently does not refreeze, Shifting the equilibrium to make more water, which will in turn be removed from this equilibrium by the salt. This is the result of a colligative effect. One major assumption that is incorrect in seemingly all of these answers is that the melting point and freezing point are the same. The salt Ions lower the freezing point by nature of their interruption of the formation of hydrogen bonds settling into a crystalline structure (colligative effect of solute in solution). However, once frozen, the ions dispersed within the water in a crystalline state actually RAISE the MELTING POINT by a completely different mechanism. This is a product of intermolecular forces. The intermolecular forces in pure ice crystal is solely hydrogen bonds. When salt is included into this lattice, the intermolecular forces increase, as a result of an increased attration between ion-dipoles interactions as opposed to simply dipole-dipole interactiom (pure ice). An increase in intermolecular forces is not the same as the colligative effects of adding a solute, while both raise the boiling point of a solution, intermolecular forces increase the kinetic energy necessary for a vapor molecule to escape the liquid, thus lower the vapor pressure, whereas colligative bP elevation/ vapor pressure depression is a result of less solute particles taking the place of solvent particles on the surface of the liquid, decreasing the likelihood of a vapor molecule escaping the liquid and as a result has a quantifiable effect directly related to the concentration of the solute.
why people cheat infidelity signs how many people cheat
hillcrest abortion clinic abortive live abortion video
hillcrest abortion clinic stories of abortion live abortion video
married woman looking to cheat My wife cheated on me most women cheat
levaquin pill diprolene 0.05% furosemide pill
imitrex 50mg site flagyl 200mg
coupons for prescriptions new prescription coupons prescription drugs discount cards
viagra coupon card free prescription cards discount viagra free coupon
pfizer coupons for viagra viagra coupon viagra discounts coupons
coupon for viagra viagra trial coupon viagra discount coupons online
can i take minocycline with birth control can i take minocycline with birth control can i take minocycline with birth control
lisinopril and bisoprolol lisinopril and bisoprolol lisinopril and bisoprolol
viagra bestellen online viagra pillen kruidvat pillen kopen
where buy viagra online side effects from viagra use online viagra buy
where buy viagra online side effects from viagra use online viagra buy
cialis coupon lilly click transfer prescription coupon
cialis coupon lilly blog.nvcoin.com transfer prescription coupon
drug discount coupons link discount coupons for prescriptions
lilly cialis coupon click coupons prescriptions
augmentin générique arbot.cz augmentin sirop
champix alkohol go champix
flibanserin online flibanserin buy flibanserin buy
cefdinir red stool ski-club-auringen.de cefdinir nedir
amlodipine 5 mg amlodipine bijwerkingen amlodipine accord
renovacija stanovanja click renova g
prescriptions coupons coupons for prescriptions drug prescription card
vivitrol alcohol naltrexone alcoholism medication narcan challenge

- Billy (age 21)
Birmingham, AL
A:

In looking over your discussion, there seems to be one point on which we clearly disagree. You write "One major assumption that is incorrect in seemingly all of these answers is that the melting point and freezing point are the same. " The equality of the thermodynamic melting and freezing points is not just a feature of some detailed model. It follows directly from the fundamental laws of thermodynamics. For a given solution concentration one phase or the other has the lower free-energy at each temperature, and that phase is the stable one. There's just one temperature where the free-energies are equal, and that's the melting/freezing point. For non-saturated solutions, the concentration changes as the freezing or melting occurs, giving a melting/freezing range. However, at each temperature in that range a precise fraction of the material is melted in equilibrium, regardless of previous history.

Interactions between ions of salts do change the magnitude of the freezing point depression and boiling point elevation, giving a correction to the simple colligative values except for very dilute solutions. The type of argument you give, trying to pick up various terms in the dynamic behavior separately, is tempting to use for pictures but famous for leading to wrong conclusions. The deep and rigorous rules of thermodynamics are a reliable guide to equilibrium properties, although not to rates.

Mike W.

types of abortions the weeks of pregnancy what happens when you get an abortion
free prescription cards go walgreens prints coupon codes
discount card prescription damske.com print cvs
online discount pharmacy dotnetblogengine.net coupon for prescription
discount prescriptions coupons pet prescription discount card internet drug coupons
can i take minocycline with birth control read can i take minocycline with birth control
can i take antabuse and naltrexone can i take antabuse and naltrexone can i take antabuse and naltrexone
lisinopril and bisoprolol lisinopriland.net lisinopril and bisoprolol
cialis dosage and go cialis dose for copd pts
diabetes affect sexuality diabetes sexuality treatment
cialis manufacturer coupon link prescription drug coupons
cialis coupon lilly blog.nvcoin.com transfer prescription coupon
lilly cialis coupon click coupons prescriptions
augmentin générique read augmentin sirop
naprosyn roche rileytech.net naprosyn nedir
champix alkohol mdwguide.com champix
kamagra wikipedia click kamagra shop
cialis cialis cialis walgreen coupon
voltaren retard voltaren forte voltaren spray
voltaren retard voltaren forte voltaren spray
cialis coupon card coupon prescription cialis coupon
vivitrol alcohol naltrexone alcoholism medication narcan challenge

(published on 07/27/2013)

Follow-up on this answer.