Melting Definition and 267 Threads

Hello everyone! I recently read some information about the equipartition theorem and degrees of freedom in thermodinamics. I read that for the linear N-atomic and non-linear N-atomic molecules in order to allow the vibrational degrees of freedom to appear we need a really high temperature. I...

Once synthesized, can YBCO be melted down to add more material or change the doping and still result in a functional superconductor?

Hello everyone! I recently saw a problem about some ice in 2 containers. So: We have 2 vertical cylindrical containers, which have perfect insulating walls, one with surface of the base S and the other one 2S , filled with the same mass of ice. The question is if there is any diffrence between...

When an ice melts on water, which was initially floating on it, the water level must get increased. Why it remains unchanged??

I understand why an impure solid will have a decreased melting point, however, in my recent organic chemistry lab section I mixed two finely ground pure solids together and observed that the mixture melted at a lower temperature than either pure solid. I understand this in principle, but...

I am building a nozzle for my hot glue gun, and it has made me realize that my math skills have become quite rusty. My goal is to figure out how fast I can extrude a hot glue stick through nozzle of different lengths. My assumption is that the longer the nozzle is (assuming I keep it at...

Homework Statement Suppose a room with 75 m3 of air also contains 80 kg of glycerol and the initial temperature in the morning is 16 °C. If 1.2 kWh of heat is added to the room between morning and afternoon, calculate the final temperature of the air in the room in the afternoon. Use 18 °C for...

How far down can a nickel ball of radius r and temperature Tn melt into the ice block of temperature Ti? Watch the video and state your assumtpions...

Hey guys What's the connection between an increase in pressure and the melting point of ice? Ice contracts as it melts so does an increase in pressure reduce or increase the melting point?

Why am I not shocked when I stir the molten metal bath of a 1000lb induction furnace? Alumina crucible used.

Homework Statement how many photons (lambda=620*10^-9) must be absorbed to melt 2kg block of ice at 0deg into water at 0deg? and on average, how many H2O molecules does one photon convert from the ice phase to water phase? Homework Equations E=hc/lambda The Attempt at a Solution I have no idea...

So I'm trying to model the process of towing an iceberg from Antarctica to elsewhere to use for fresh water. I hit a dead end trying to find how much of the iceberg would be left. I know it takes 333 J/g to melt ice and the mass of the iceberg is 7 million tons so i know how much energy it...

I'm building an frame out of solid 5/8 inch thick aluminum square bars. this frame will be around a fire temps close to melting points but there will be insulation in make sure it won't melt. I was thinking about drilling holes in the free space of the aluminum to reduce it's weight and if you...

Homework Statement When lead is melted at atmospheric pressure, the melting point is 600K, the density decreases from 1.101x104 to 1.065x104 kgm-3. The latent heat is 24.5 kJ kg-1 Estimate the melting point of lead at a pressure of 100 atm. Homework Equations I haven't been able to find any...

Hello Forum, In the context of polymers, I have see two different temperatures being mentioned: T_g and T_m (T_g is the glass transition temperature and T_m the melting temperature). Which temperature should be considered for plastic extrusion applications? The melting temperature T_m? What...

What material has the lowest melting point? I'm doing an interesting research project of finding an invisible ink. My purpose is to find a material on which I can write on and has a very low melting point. I want to write on this kind of material by using my invisible ink. From my research...

Why does copper have a higher melting point than aluminium? Why does the melting point increase as you go down groups anyway? Aluminium has higher charge (+3) and a smaller radius, meaning that there is a higher charge density and thus stronger forces of attraction to the lattice. While copper...

I know the specific volume for Ice is higher than water so increases in pressure make it more favorable for the ice to go to water (hence a negative slope on a phase diagram rather than positive) Is there a point at which if the pressure was so high that it would be have to be liquid no matter...

Homework Statement The Attempt at a Solution My answer was C but the correct answer is A. My reasoning is that they are all bonded to chlorine, so the further away the element is from chlorine on the periodic table, the more ionic the compound is and the higher the melting point is. The...

I just read that sodium has a higher melting point than neon. As neon is a noble gas, how can it have a melting point if it isn't a solid?

Homework Statement Velma and Mort have identical 10-minute melting ice-cream cones. How fast must Velma move in order for her 10-minute cone to last 3 times longer than Mort’s, as measured by Mort?Homework EquationsThe Attempt at a Solution [/B] We have not gotten too in depth into...

So at increased pressure (increased atmospheric), the boiling point of water Increases because the atmospheric pressure goes up. But at increased pressures, the melting point of a substance decreases! The explanation i'v seen is that it is due to le chatlier's principle. Ice is less dense...

Can someone please explain why the melting point of ice decreases with increase in pressure? I understand that generally speaking for a solid, greater the pressure applied, greater energy needed to break the bonds to change state and hence greater the temperature (melting point). What is the...

Homework Statement Calculate the entropy change of an ice cube of mass 10g, at an initial temperature of -5°C, when it completely melts. cice = 2.1 kJkg-1K-1 Lice-water = 3.34x105 Jkg-1 Homework Equations dQ = mcdT dS = \frac{dQ}{T} ΔS = \frac{Q}{T} Q = mL The Attempt at a...

Homework Statement If 25.0 g of gallium melts in your hand, what is the change in entropy of the gallium? What about the change of entropy in your hand? Is it positive or negative? Is its magnitude greater or less than that of the change in entropy of the gallium? The melting...

Hi, Is it correctly understood that it's the intensity of light that causes melting or heating of objects and not frequency or vice versa? I'm trying to understand the ultraviolette catastrophe (what the problem was) and according the the equation for intensity (given below) frequency...

Homework Statement If a snowball melts so that its surface area decreases at a rate of 10 cm^2/min, find the rate at which the diameter decreases when the diameter is 11 cm.Homework Equations I don't know what i am doing wrong.The Attempt at a Solution A=4(pi)r^2 dA/dt=...

I am presented a review of data which gives: vapour pressures of a liquid have been measured and fit to the following equation: Log10 (mmHg) = -3571/T + 8.999 The melting point has been determined to be 392.7 K. A Cp value given for the liquid is 250 J/mol K and the ΔSvap is 117 J/mol K...

Homework Statement Vapour pressures of a liquid have been measured and fit to the following equation: Log10 P (mmHg) = -3571/T + 8.999 The melting point has been determined to be 392.7 K. A Cp value given for the liquid is 250 J/mol K and the ΔSvap is 117.20 J/mol K Homework Equations...

Homework Statement The vapour pressures of a liquid have been measured and fit to the following equation: Log10 (mmHg) = -3571/T + 6.124 The melting point has been determined to be 392.7 K. Calculate the standard entropy of the liquid at the melting point. Homework Equations...

Homework Statement How do you explain that crystalline melting temperature Tf of PE is greater than the Tf of PEO? How do you explain that the glass transition temperature of PP is lower than the glass transition temperatures of PVC and PS? Homework Equations None The Attempt at a Solution...

I was sitting by a camp fire this weekend and I noticed that the snow/ice around the fire was melting in a strange way and I couldn't think of a good reason as to why it would leave this pattern. Essentially, it looked like small icicles all aimed towards the fire, almost parallel to the ground...

Does anyone know an approximate voltage needed to melt the filament of a typical 120V/60W incandescent bulb? I'm doing a research project and I've calculated 211V. However, I don't have a power supply capable of delivering it - yet. So for now I can't test my theory. and I haven't had...

Homework Statement https://scontent-b-dfw.xx.fbcdn.net/hphotos-prn1/v/1012733_10201076259690370_236735593_n.jpg?oh=4896ca67a34d3b223b764aba8ed308ab&oe=528A1B57 Homework Equations http://upload.wikimedia.org/wikipedia/commons/3/34/Phase-diag2.svg The Attempt at a Solution Not sure entirely...

When a solid is heated, its kinetic and potential energies increases. Up to a certain point, the kinetic and potential energy is so high that any heating done to it would only increase the potential energy and not the kinetic energy of the solid anymore. When this happens, some of the...

Homework Statement For the following melting point, indicate what might be concluded regarding the sample purity: Melting point: 147ºC (dec.) Homework Equations I assume that (dec.) means that the sample decomposed. The Attempt at a Solution I am wondering if this means that...

Though this topic mentions climate change, I don't think it really is about it that, strongly anyway. I've just joined and noticed a ban on climate change discussions before posing this one, I don't think this is one, but if it is, I suppose the beast must have one of it's many heads chopped...

I have a pretty stupid question that I hope someone can answer. I'm trying to deposit chromium and vanadium in UHV, and I need to determine whether each of the materials will "melt" or "sublimate" so that I know the volume to fill my crucible. My impression is that these materials will...

In diamond valence electrons are fully covalently bonded.But in graphite only three are covalently bonded while one electron is freely moving.So it seem that melting point of diamond should be higher than that of graphite because in diamond we should break four covalent bonds while in graphite...

Why a silica powder is melting but not burnt when heated? Thank you

What would happen if I trawled one of the oceans garbage patches (say the great pacific or atlantic garbage patches) and put everything I trawled into a furnace with an inert gas hot enough to melt the majority of plastics I picked up, what would be the outcome? I am looking to know more...

Homework Statement A)You have a tank containing 750 mL of water and a heater outputting a max of 400 W. If you start with the water at 25 degrees, how long till it reaches boiling point? B) How much heat must be input to melt 1 gram of ice? What is the volume of meltwater does this produce...

Hey folks, I'm trying to obtain the melting points of several materials in a vacuum. It's pretty straightforward to look up the melting point in 1 atm, but I'm having difficulty doing this in a vacuum. One material in particular I'm looking at is Teflon. If anyone can provide any...

Homework Statement Assume that a wax candle with mass m at temperature T1 undergoes constant heat admission dQ/dt=Kp Assume: m=50g T1=25 celsius Kp=10W Calculate how long it will take for the wax to melt and vaporise during constant heat admission without any loss. Data: ρ=791...

I'm currently looking into some dental material mechanics. Material: Pressable ceramic powder Melting range: 900-1000°C If I were to heat it up to approx 1200°C, what would happen to it? Would it still be just molten form of the material? Student

Hello Wizards! I need to produce specially pure iron shapes for a research project. As you may know, pure iron is hard to find. Small pure iron bars are the easiest. Is it possible to melt and cast these small pure iron bars into other shapes, without the iron losing its...

Homework Statement You throw a snowball at 0.0 Celsius at a brick wall. If you want it to melt completely, how fast will you have to throw it? Homework Equations Q = mL E_k = \frac{1}{2} mv^2 The Attempt at a Solution I initially reasoned that you would use Q = mL to find the energy...

Hi, As I understand, during the process of phase change from a liquid to solid (or any phase change for that matter,) the temperature of the substance remains constant as the energy being applied to the substance is used in changing phase. How does this relate to Gibbs free energy? I read that...

Hi all, I am posting as a layman, whose 16 year old son has been issued with a court summons for criminal damage against a neighbour's car and driveway. A few weeks ago my son thoughtlessly emptied a small glass candle jar out of his upstairs bedroom window into what he thought was the...

Using a 30kg cubic block Ice at -20degC, I want to cool down a piece of steel which is resting on the seabed. The mass of steel is 1kg and the ice block is place on top of the steel. The current sea temperature as well as the steel temp is estimated at 12degC Assuming that the piece of steel...