Melting Definition and 275 Threads

There was a post on stackexchange.com explaining the trend in melting/boiling points of first series transition elements. https://chemistry.stackexchange.com/questions/4766/melting-and-boiling-points-of-transition-elements The specific question was...

Energy lost by water = Energy gained by ice Energy lost by water = 0.16 x 4200 x (100-t) Energy gained by ice = 0.205 x L + 0.205 x (t) (where t is the temperature at thermal equilibrium). However, there does not appear to be enough info to continue. The solution, however, considered t to be...

I suppose it means that the gadolinium melts only at one particular location, but I have no idea how to take it mathematically. Could I just say that local melting is when I destroy a bond between two gadolinium atoms? Could I calculate with this? I just need to understand what I am supposed to...

For this, Why dose they write the change in entropy equation as ##\Delta S = \frac{Q}{T}##? Would it not better to write it as ##\Delta S = \frac{\Delta Q}{T}##, since it clear that we are only concerned about the transfer of heat in our system while it remains at constant temperature as all...

During the procedure, 30% of heat is lost. So that means that 70% of water+container is contributing to melting the ice, right? And the other 30% contributing melting the ice is down to, well, the "heat being lost to the surroundings" (not sure what this really means). We compute the sum and...

I am looking to try to create an alloy of gallium (probably with Tin) with a goal of increasing the melting point from 29°C to around 40°C. My current theory is to simply try to average the two melting points out by mass, which my calculations imply means 95% Gallium to 5% tin. my calculation...

how long does it take a 12.5 kg gold bar to melting at 3000 degree C°? Why does the water coming out of the waterjet slow down after a while?

A 3d printer that could print metal and other materials would revolutionize everything. The only problem is that metals have a really high melting point, so if you try to get a metal hot enough to bind to the other metals in its vicinity it would probably destroy the bonds of the neighboring...

Table boiling point (°C) melting point (°C) TiF4 284 N/A TiCl4 -24 136.5 TiBr4 38 233.5 TiI4 155 377 The solution says that TiF4 is an ionic compound, while TiCl4, TiBr4, and TiI4 are covalent compounds. How would I determine this from the problem without prior...

I don't know how to make an equation from this task. I tried doing this: Q1=Q2 m1Cv(t2-t1)=m2Qi m1 - mass of the ice m2 = mass of the water that's left after melting t1 - temperature 0C t2 - temperature 100C Qi = 2.25 x 10^6 J/kg This is my first post here I hope I didnt break any rules. Cheers !

Adiabatic increase in pressure implies Tds=0, can someone tell me how to proceed?

First, I calculated the heat required for the ice to melt: Q=mLf Q=0.150×330 Q=49.5 J Then, I calculated the final temperature of the water by forming the following equation: Q=mcΔT −49.5=(0.15+0.35)×4200×(Tf −80) Tf=80.0 degrees Celcius But the answer says 32 degrees Celsius.

##dmL_f= Q \; \; ##,##∆T=\frac{T(v_l-v_s)∆P}{L} \; \;##,##\frac{dmL_f}{T_0}= dS_2 \; \;##,##\frac{dmL_f}{T_1}= dS_1 ##

There was a question on "Why salt lower the freezing point of water?"I found the following answer."Thermodynamics teaches that a loss of entropy can be overcome by a gain in so called enthalpy". The loss of entropy by freezing the solution canbe over come at temperature much below 0 degree C...

I've got a kitchen bowl made of polypropylene, it states that the "heat resistance temperature is 90 degree cel", while on Google, I found that the melting point of PP is 160 degree cel. I understand that melting point is the temperature in which the atoms/molecules change its state from solid...

So to begin this question, I do know that volume =4/3 pi r cubed, while the surface area) 4 pi r squared. I will like to clarify some things about the question: 1) does the first sentence means dv/dt is proportional to 4 pi r squared? 2) given the second sentence how am I able to construct an...

Hoping for feedback regarding engineered conductors that has high melting points (>4000C). Does anyone perhaps know of such metallic alloys or conductive material? (please, no 2D/1D materials -- exotic materials/alloys are OK, just has to be able to be made in bulk!) Thank you!

I am interested in a water heater found in consumer market, however, it's made of kind of plastic, I often "feel" that there must be some problem heating up something like plastic. I understand that it should be tested and safe before putting into the market, however, I still wish to know -...

The question says that the process is melting, so temperature must increase. Hence, Delta T > 0. Also, it is given that the slope for its fusion curve is -ve, which means that as we increase temperature, the pressure will decrease. So, Delta P < 0. The question asks to prove that the substance...

It turns out that the solid form is the same for the two situations but the liquid is two different isomers depending on external conditions during melting. https://physicstoday.scitation.org/do/10.1063/PT.6.1.20190606a/full/

Good morning, I'm wondering on this question for a while. Imagine we have a fire progressing in a corridor 30 meters wide at a known velocity. What kind of barrier (of the following) can be most successful in minimizing or even erasing this fire and why: a water-soaked area, or a zone covered...

Why quartz has a higher melting Temperature than glass? Which one is harder and why?

I had heard an opinion from my high school teacher, but I can't understand?? "An experimental record of a French scientist. He heats the diamond and sublimates it. After cooling, it turns back to solid barbecue carbon. In this case, although there is a physical transition, the substance seems...

As I mentioned in subject, I want some molten aluminium. Is it dangerous for human health to do it? Should i use some protection?

I’m using a zvs inductive heater to try to melt some 99.85% polycrystalline silicon, as would occur in the Czochralski process, but the silicon workpiece is not melting let alone even getting hot. The silicon workpiece is about the size of a playing dice, and becomes fully conductive after...

I recently saw the movie “Man of Steel”. In Superman’s fight with Zod, Superman cuts (by melting) a steel I-beam, that Zod is about to hit him with, with a swipe of his heat vision. To melt steel that fast (under 3 seconds) requires a large temperature. My question is how can we calculate the...

I used sailcylic acid and acetic anhydride to produce aspirin and preformed recrystalisation to purify the aspirin. I need to evaluate why I have a higher/lower melting point. In this case, the melting point was 143°C whereas the true meling point is 135°C. I thought one of the reasons my...

Homework Statement A 0.25 kg piece of ice at -30 C is warmed by an electric heater and the following graph of temperature is produced. Assume that there has been no loss of energy to the surroundings. - Use the info on the graph to determine the power output of the heater - Explain how long...

Why doesn't wood melt and ice burn?

Homework Statement In an electric circuit, consisting of copper wires with cross section area of Sc=5mm2 and a temperature of t=25C, a lead fuse is added melting when the copper wire temperature increases by Δt=25C. Find the cross section area of the lead fuse wire Sl=x. specific heat...

Homework Statement Question (b) (iii) Homework EquationsThe Attempt at a Solution The energy required to melt the ice is Q1=mL=3*0.025*3.3*10^5=24750J The energy released by water is Q2=mcT=0.33*4200*(22-T) Shall I calculate the energy that the ice needs after it melts into water? i.e...

Hello. I know this is a dumb question but I am just learning chemistry. Ok, for collision theory, atoms need a certain amount of energy to bond, because they need to break old bonds and form new ones. Makes sense But, at high temperatures, things become gaseous. At low temperatures, things...

Related to exploration of Europa: If we elect to send a probe to bore through (guessimate) five kilometers of ice to reach the Covered Seas, and have a diameter of 100 mm and length of one meter, how much energy will the probe require to reach unfrozen areas? AND given that figure, is it...

Homework Statement On a hot summer day, you planned a trip to a beach, but you inadvertently took a wrong turn and now you’re worried the ice in your cooler is going to melt. The cooler is 0.5 m × 0.5 m × 0.4 m, and is made with 5 cm thick Styrofoam (k = 0.033 W/m2K). Help your panicking...

Good day members of physics forums . I am a university student currently studying thermodynamics and I just am a bit confused about a heat transfer problem. If you have the following items: 1 metal container which is well insulated from the outside ; ; 1 quantity of water and an icecube ...

Homework Statement An ice cube at the melting temperature that has a mass of 20 g, is struck by a bullet with a mass of 9 g, flying at a certain speed. Determine the speed of the bullet, if it is known that one third of his energy was consumed to break the ice, and the remainder to melt it...

Homework Statement The problem is that a Carnot contains Boiling water in the hot reservoir and ice water in the cold reservoir. Given that 0.0400kg of ice is melted in 5 minutes, what is the amount of work done by the engine. Homework Equations Qh/Qc=Th/Tc W=Qh-Qc W=(1-Tc/Th)Qs q=mHf...

It seems Chip Knappenberger of the Cato Institute, who is considered something of a global warming skeptic, has made an interesting statement. “Natural variability is itself is becoming increasingly ‘non-natural’ as it includes influences which themselves are shaped by anthropogenic...

Homework Statement The following chart shows the temperature before and after Melting Ice. (A, B) have the same amount of water. If the heat required to fuse both cube are equal. The ratio between the two cubes mass: Cup Before After A 25 21 B 25 23...

Does anyone know of any solutes (such as sodium chloride) that have VERY high melting points (preferably 1800C or higher)? They don't have to be water soluable but they need a solvent that can disolve them.

Why there is huge difference in M.P. and B.P. Of Oxygen (M.P. - 54K,B.P.- 90K) and sulphur (M.P. - 393 K, B.P. - 718 K)

Homework Statement In an insulated vessel, 265 g of ice at 0°C is added to 630 g of water at 17.0°C. (Assume the latent heat of fusion of the water is 3.33 105 J/kg and the specific heat is 4 186 J/kg · °C.) a) What is the final temperature of the system? b) is already solved Homework...

My books says Thermite reaction is an exothermic reaction, it release large amount of heat so that temperature increases upto 3500°C On the other hand it is written Melting point of diamond is 3500°C So my question is whether diamond can by melted in such reaction?

A spherical snowball is melting at a rate proportional to its surface area. That is, the rate at which its volume is decreasing at any instant is proportional to its surface area at that instant. (i) Prove that the radius of the snowball is decreasing at a constant rate. can someone help me?

Quoted data for cis and trans 1,2 dichloroethenes shows cis has higher density but lower melting point than trans. How can this be explained? Packing arguments are clearly unable to rationalise these observations. Other 1,2 disubstituted ethenes show similar pattern. Thank you.

Homework Statement http://imgur.com/Sk6YkIf . You can take Va to be volume of cavity and Di to be density and Vo to be volume of cube and A to be surface area of container and h to be height of liquid column and Vi to be volume of immerser part of cube. Prove if water level will rise or will...

Homework Statement Homework Equations equation with each part. The Attempt at a Solution I did part a) b) and c) on my own: Part d: I am having trouble at this part. I understand how to draw the heat curve but I am confused on what numbers I should use for the x-axis of the graph. I...

Homework Statement Consider a closed, adiabatic system consisting of a mixture of liquid and solid substance Z at equilibrium at its melting point. Z (solid) <---------> Z (liquid) Which of the following statements is true regarding the system? A) The entropy of the system is at a maximum...

Hello, I was doing melting and solidification of ice kept inside a annular cylinder. The temperature of inside wall of cylinder is 80 degree. Now i want to analyse the total time consuming to melt the ice and plot temperature variation with time. Actually i did analysis but the result i found...

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...