Melting Definition and 275 Threads

Homework Statement You have 0.9 L of water in an insulated (thermally isolated) cup at 20 ºC. You add 360 g of ice at −20 ºC in the cup to cool the water. Describe the final state of your system in terms of (i) number of moles of ice (ii) number of moles of water and (iii) the final...

I know this question is probably chicken feet to most of the people here, and I hope I am posting on the right thread. But I am just curious about 2 questions; 1 - Where does the kinetic and potential energy comes from in a substance? 2 - How are the kinetic and potential energy affected by...

Say we had some solid and it's being heated up towards it's melting point. It reaches that temperature, and then an infinitesimal increase in temperature T will cause the crystal to break apart. It loses its ordered structure and so the entropy S has increased. If I'm not mistaken, any...

Homework Statement A student performed the reaction in this experiment using a water bath of 90 degrees C instead of 50 degrees C. The final product was tested for the presence of phenols with ferric chloride. This test was negative (no color observed); however, the melting point of the dry...

Homework Statement If ice is at(-12) deg c and has a mass of .55593125kg, how much heat is required to melt the ice. Homework Equations Q=mcT The Attempt at a Solution i tried Q=mc(water)T and Q=mc(ice)T but both were marked wrong. can you show me what I am doing wrong here?

How can an element boil before it melts? I came across this- As - Melting Point 816 C and Boiling Point 615 C. Every other element given along with this element in my book has its melting point lower than boiling point which makes sense to me. I am curious to know what is different about As...

why is "melting" called "fusion"? any idea why is "melting" called "fusion"? molecules during melting are moving farther apart, they are not "fusing" together. It seems counterintuitive to call "melting" "fusion"

In Atoms in the Family: My Life with Enrico Fermi, Laura Fermi explains some of the games they played when they were in college. The following is an excerpt from the book which I need help understanding. "As you know, the boiling point of olive oil is higher than the melting point of tin. How...

i was just reading an article i got linked to from google, about the North magnetic poles location is moving towards siberia currently at about 45k per year, which has increased over the past 100 years from around 15k per year, it was explained that it was possibly caused by density variations...

Hey PF, I normally frequent the EE portion of this board, but I had a question about plastics and plastic injection molding. A buddy and I have an idea to create a rather small and specific plastic object in large quantities. We thought that to create small prototype quantities, we could...

I wonder if melting deteriorate the crystalline properties and order of a solid? For example, one should expect to get 2 different Raman spectra from the solid and melted samples?

Homework Statement An insulated Thermos contains 190 cm3 of hot coffee at 83.0°C. You put in a 18.0 g ice cube at its melting point to cool the coffee. By how many degrees (in Celsius) has your coffee cooled once the ice has melted and equilibrium is reached? Treat the coffee as though it were...

Hello all... Help... :confused: my teacher gave us this question and... no matter how I approach this question, I just can't solve it... The question asks... an ice block melts and slides down a plane of rough surface.. The mass of the ice block starts at 3 kg, and its mass...

Homework Statement The density of solid water is approximately 920 kg m^-3 and that of liquid water is 1000 kg m^-3. Calculate the melting point of ice under a pressure of 6000 kPa. Homework Equations This is my problem. How do I approach this? I don't see any relevant equations in my...

I am using Tyvek for a project and need bond it together. I thought melting it together would the best way. Would that be safe. MSDS...

Homework Statement So this is not really a homework problem, but it is an academic-related problem which I want to solve. Suppose in my current research position, I'm making synthetic Collagen heterotrimers, composed of A,B,C monomers, which form into a triple helix arrangement. Each monomer...

Q. 1. if a ice cube is placed in a container containing liq on which it is floating. then is it possible that after ice melts, water level rises in vessel in any particular case. 2.Does heat evolves when water rises in a capillary. and how much heat is evolved in height of liq in capillary...

I have a que. if a ice cube is placed in a container containing liq on which it is floating. then is it possible that after ice melts, water level rises in vessel in any particular case. Does heat evolves when water rises in a capillary. and how much heat is evolved in height of liq in...

Why does the salt melt the ice , and if i put a soda in a cooler then put ice on it and then put salt on it , it will start to melt the ice and then cool the soda faster then with just ice alone , is it correct to say that the melting of the ice requires heat , and it pulls the heat from the...

anyone tell me why melting points of any substance decrease when we add any other material

Homework Statement An insulated beaker with negligible mass contains liquid water with a mass of 0.325 \rm{kg} and a temperature of 69.9 C. How much ice at a temperature of -15.0 C must be dropped into the water so that the final temperature of the system will be 39.0 C? Take the specific heat...

Homework Statement What quantity of ice at 2 deg Celsius can be melted by 100 J of heat? Homework Equations q = m c (delta) t (mass x specific heat x change in temp) q = m l (mass x heat of fusion) specific heat of ice = 2.09 j/g-K heat of fusion = 6.01 kJ/mol The Attempt...

Homework Statement A girl wishes to make a lead casting of an object which will require 2kg of melted lead. if the lead was stored in her basement at approximately 55 degrees F, and it is melted to a 1/4" thick steel pot of approximate cross sectional area of 12in^2, how long will it take...

Here is the original question: - Well, the answer that I came up with is, that, since there is no eternal force on the system, the centre of mass cannot be displaced, no matter what. Now, my doubts are regarding this itself. When the ice melts, it turns into water of lesser volume. In the...

Hi, I'm currently doing experiments on a 99.9% TiO2 source powder. I was wondering if there is anyway to lower the melting point of this solid? If possible, without compromising its purity. I only have access to an electrical furnace that is capable of reaching a maximum of 1200 degC...

what method can be used to keep a regular 2cmx2cmx2cm ice-cube from freezing. i need to find a way to keep an ice cube solid for 10 hours after taking it out of the freezer without using electricity or by adding more ice etc. the question comes from my chemistry lecturer so i would expect it to...

Homework Statement For a protein denaturation the entropy change is 2.31J/Kmol at P = 1.00 atm and at the melting temperature T=338K. Calculate the melting temperature at a pressure of P= 1.00x10^3 atm if the heat capacity ∆Cp,m= 7.98J/Kmol and if ∆Vm=3.10mL/mol. Homework Equations...

Homework Statement 175 cm3 of hot tea at 87°C are poured into a very thin paper cup with 80 g of crushed ice at 0°C. Calculate the final temperature of the "ice tea". (Hint: think about two processes: melting the ice into liquid and, maybe, warming the liquid.) Homework Equations...

Alright, so I've posted this in physics forum not so long ago, but still haven't gotten any responses. Ok, so we know that the more electrons there are in the valence shell of an atom, the stronger the London Dispersion Forces are, and therefore, the compound will have a higher melting and...

If I have a piece of ice melting in a water and eventually comes to equilibrium with the water... The the total enthalpy change includes the following right? Heat absorbed for ice to get to 0 degrees Heat absorbed for ice to melt to water Heat absorbed for the melted ice water to come to...

Why caffeine has 178 oC as point of sublimation but 237 oC as melting point? Is it about the pressure? If so, then what is the preesure that makes 237 as melting point instead of sublimation at 178 oC? Cuz the science websites always just said 237 is the melting point, but didn't mention the...

Homework Statement Hi all I have conceptual problems : 1. In cold countries, water in pipe lines freezes in winter season. Freezing causes volumetric expansion and may burst the pipes. My question :why freezing causes volumetric expansion? 2. Mostly, substance increases their...

Homework Statement An unknown compound gave a melting point of 230C. When the molten liquid solidified the melting point was determined to be 131C. Give a possible explanation for this discrepancy. Homework Equations The Attempt at a Solution I understand that melting point...

Hi physics geniuses! I've been awake all night (grr!) trying to figure out some stuff we talked about in our calculus-based physics class today about Relativity. I hope you guys can make this all clear to me, because maybe then I can get some sleep! OK, so our professor told us this week...

What is the melting temperature (in fahrenheit) of diamond?

Homework Statement hey guys, just wondering if you could tell me which of these is polar and how to do it thanks? the question is asking for the highest melting point, so i believe it relates to which is polar. any help would be greatly appreciated. Homework Equations Which of the...

I have tried a quick scan of the web for general information relating to the depression of melting points and found very little available, so i started this thread. The general idea is a depression curve which will help you identify by how much a sample contains impurities. I was looking for...

Here is something that I see every spring, when the sun gets higher in the sky and the temps moderate. Notice the depressions under the raspberry canes... The sun heats up the canes, both above and below (reflection from the snow) and the canes re-radiate IR, melting the snow below them, even...

When you take bottle of glass and fill it with some ice what happens to watersurface when ice has melted away? Does it rise surface? Or will it remain the same? Teacher spoke and demonstrated that and it didn't rise the surface. I believe in my eyes but is there any physical way to prove that...

Hoping someone could double-check for me... Homework Statement 1) A 90 g block of unknown metal is heated to 86 degrees C and put in an insulated cup with 175 g water at 23 degrees C. At equilibrium, they are both 25.8 degrees C. What is the specific heat of the metal block? 2) A well...

Dear all, I have some problems with a program called the simulation of laser interaction with materials. In this program, they asked for some parameters which I am unsure of but I believe it has something to do with mesh size for simulating the thermal conduction. This is a 1D heat conduction...

You know that dirty disgusting snow that accumulates on sides of roads over the winter, and then doesn't melt until well into May or something? Why is it that this snow refuses to melt? It mixes with dirt and exhaust fumes from the cars, and somehow becomes really hard and un-meltable. Does...

Homework Statement The density of ice is 0·92×103 kg m−3 and its latent heat of fusion is 3·3×105 J kg−1. Estimate the melting temperature of the ice at the bottom of a glacier which is 100m deep. Homework Equations L = Tc(S2 - S1) The Attempt at a Solution (S2 - S1) = 1208.8 I then...

Hi, I live in the northeast, well known for its heavy snowfall in the winter. Where I live, for the past few days, it has been raining heavily during the daytime and stopped at night. This has collected in various ducts and pipes meant to remove the water from the roof. At night, when the...

Homework Statement A pure ice cube sits in water, floating. Prove that the water level will not change after the ice cube melts (meaning, the volume displaced by the cube will equal the volume of water added once the cube is melted). density of water = 1000 kg / m^3 density of ice = 920...

Homework Statement Consider the melting of one kg of ice (solid H2O) by slow, reversible addition of heat at one bar of pressure and a temperature of zero degress Celsius. Calculate q, delta U, delta G, delta V, and delta S. In this case we take the "system" to be the water. The molar...

1. What is the pressure needed to increase the melting temperature by 20 centigrade degrees? Given: Molar Volume (solid) at normal melting temp is 18.92 cm^3 Given: Molar Volume (liquid) at normal melting temp is 19.47 cm^3 Homework Equations delta H (s>l) = T(melting point)* delta S(s>l)...

Hi all I am sorry for the double post, I just found out there is a homework help place here.. I have this question in a practice physics exam: The table lists melting and boiling temperatures of 4 different substances, A,B,C,D.. The question is "Which substance is a gas at 25 C?"...

in literature, find melting point and solubility in water of benzoic acid, vanillin, phthalic acid, salicyclic acids. Calculate the expected volume of hot water that would be requried to dissolve 0.15g of each compound. With info on melting point and solubility in water... how can you...

The densities of ice and water at 0*C are 0.9168 and 0.9998g/cm3. The latent heat of ice is 80cal/g. What is "delta"H and "delta"U (enthalpy and internal energy, respectively) when 1kg of ice is melted? I'm really confused on which formulas to use and if the densities are even relevant to this...