Latent heat Definition and 206 Threads

Homework Statement A window of a car is found to be covered with 0.8cm of ice. If the area of the window is 1 m2, and the ice is at -12 degrees Celsius, what is the minimum heat required to melt all the ice? Take the density of ice to be 900 kg/m3, the specific heat capacity of ice to be 0.5...

I understand the main concepts around this topic but I am struggling to find any information about the potential energy involved in the latent heat of fusion. My book defines internal energy as kinetic and potential unlike an ideal gas that is assumed to have just kinetic energy. When a...

When doing an experiment to find the specific latent heat of fusion of liquid nitrogen, you find that 100 kJ of heat must be removed to freeze 3.8kg of nitrogen at its freezing point. What value will you get for the specific latent heat of fusion of nitrogen? Power=100kj M=3.8kg I don't...

Hello, I know that the latent heat of a first-order isothermal and isobaric phase transition is in general given by the difference in enthalpies between the two phases, but my question is: do you know if there is there a way to estimate its value "from first principles" for the case of a...

Homework Statement You are required to calculate the efficiency of an ice-making machine that takes in water at a temperature of 16°C and produces ice cubes at a temperature of -6°C. Water is taken in at the rate of 1kg every 5 minutes and the input power to the machine is 300W. The Specific...

Homework Statement If a copper kettle has a base of thickness 2.0mm and an area 3.0 x 10-2 m2 estimate the steady difference in temperature between the inner and outer surface of the base which must be maintained to enable enough heat too pass through so that the temperature of 1 kg of...

Homework Statement A scientist heats up a substance by applying heat at a constant rate of 75 J/s. She measures that it takes 1 minute for 100 grams of the substance to evaporate. What is the latent of vaporization of this substance? If she starts with 1 kg of the substance, how long...

When using ice to keep a room (or in my case, a cooler) cold, one would want it to have a high specific heat capacity and a high latent heat of fusion, so that it would absorb a lot of energy as it melts. Basically, so that it melts as slowly as possible. I know that adding salt to road ice...

Hello, I would like to know how to calculate how long the phase transition when cooling lasts. So basically how long the latent transition lasts. I really don't have any ideas how this could be calculated, although I would assume it is function of the mass. Any help is much appreciated.

This is a question of understanding notes today:) I'm struggling to follow these notes, they are not very well written and a tad sporadic! I was just reading through them and I'm not quite sure what the term ε actually is in this case? I am assuming it is a constant although on the first page...

Evening all. I've seen this equation written down but can not for the life of me find it on tinterweb, is it correct? L = Tconst(S2-S1)

Homework Statement A 100g (.1kg) cube o ice at 0dC (d=degrees) is placed in 1kg of water that was originally at 80dC. What is the nal temperature of the water after the ice has melted? Answer: 65.5dCHomework Equations Lf = Q/m Q=(DelT)mCThe Attempt at a Solution At first I looked up the latent...

Hi all, could somebody have a look over my answers for this question please? The value I got for the second part seems quite feeble. Homework Statement The Attempt at a Solution Part a) Key m = mass cs = specific heat bronze cm = specific heat molten bronze Tfus = melting...

The latent heat of vapourisation of H2O at body temperature (37°C) is 2.42x106 J Kg-1. To cool the body of a 75 Kg jogger (average specific heat capacity = 3500 J Kg-1C°-1) by 1.5 °C, how many Kilograms of water in the form of sweat have to be evaporated? Q = mcΔT I'm confused about what to do...

Hi - I'm a physics newbie so this is an elementary question, but I can't find the answer with a google search. Water evaporates at a wide range of temperatures, what is the latent heat in the water vapor (in calories or Joules), for example, at 30°C, 60°C? Assume standard atmospheric...

Homework Statement How much heat is required to heat 0.2kg of ice from -20°C to 30°C? Homework Equations Total heat lost or gained : ##Q = mcΔt## where ##Δt## is the change in temperature and c is the heat capacity. Latent Heat Fusion : ##Q = mL_f## The Attempt at a Solution From my...

Homework Statement The vapour pressure of a certain liquid is given by the equation: \log_{10}P=3.54595-\frac{313.7}{T}+1.40655\log_{10}T where ##P## is the vapour pressure in mm and T is temperature in kelvin. Determine the molar latent heat of vapourisation as a function of temperature...

Homework Statement mass of cup 1.78g initial mass of water and cup - 54.26g finlal mass of water after ice added - 91.26g initial temperature - 27°C temperature after heated - 92°C temperature after ice added - 35°C problem 1) how much heat energy did the original mass of water lose...

Homework Statement I'm stuck in the following problem: In a particular solid-liquid phase transition the point ##T_0##, ##P_0## lies on the coexistence curve. The latent heat of vaporization at this point is ##l_0##. A nearby point on the existence curve has pressure ##P_0+p## and temperature...

I'm hoping someone can help me find information on this, I've been searching to no avail for it. I need to know the latent heat of 2, 2', 2" (Hexahydro-1,3,5-triazine-1,3,5-triyl)triethanol CAS No. 4719-04-4 at P = 480 Psig, T = 150°F. Can anyone point me in the right direction for some info...

Homework Statement I took a test and got it back I'm wondering if my prof. definition is correct. The heat required per unit mass of a substance to produce a phase change is called? A. specific heat B. Specific heat capacity C. latent heat I said it was C. He say's B Please...

I need some clarifications on the precise definitions and scope of latent heat. My textbook defines latent heat as the amount of energy absorbed or releases during a phase change process. So if I have a pot of liquid water and I vaporize it completely, then the latent heat is simply the energy I...

Hey guys, first post. I'm trying to determine to the rate at which liquids drop out of a gas pipeline. I've modeled the system in a chemical process program, but its only a steady state model. Anyways, here's some of what I can get out of that program: Heat of vaporization Total Heat Transfer...

Homework Statement The latent heat of vaporization of a substance is defined as the amount of heat required to transform the substance from its liquid into its vapor phase. A certain material has a boiling point of 700K and its molecules have three degrees of freedom in the liquid phase but...

Homework Statement A cooking vessel on a slow burner contains 11.0 kg of water and an unknown mass of ice in equilibrium at 0°C at time t = 0. The temperature of the mixture is measured at various times. During the first 50.0 min, the mixture remains at 0°C. From 50.0 min to 60.0 min, the...

Homework Statement Explain why heat loss is the same in both cases, provided the time is the same. Homework Equations VIt = mL + H The Attempt at a Solution Is it the same because in both cases I'm asked to boil off 50g of alcohol?

Homework Statement Suppose molten (liquid) lead, mass ml = 9.83 kg, is at its melting point. The lead is poured into water of mass mw = 585 g and initial temperature Tw = 16.2 C. Find mwb, the amount of the water that boils. NOTE: Reaching the boiling point is not enough; the question asks...

Homework Statement Assume that a hailstone at 0◦C falls through air at a uniform temperature of 0◦C and lands on a sidewalk also at this temperature. From what initial height must the hailstone fall in order to entirely melt on impact? The acceleration due to gravity is 9.8 m/sec2 and the...

A styrofoam cup contains 2.00x10^2 g of water at 21.0°C. A student adds 60.0g of ice at 0°C into this cup. Determine the mass of ice in the cup when the ice-water mixture reaches equilibrium. Qcold = -Qhot no idea where to start

Hi, I have conducted an experiment for finding the latent heat of liquid nitrogen using a 5W power supply and a 200 ohms resistor. As part of my conclusions I am asked to discuss/refer to the resistor's temperature during the experiment. I am not sure whether I am expected to provide a...

Does latent heat of fusion typically go up or down with temperature? I'm trying to calculate the amount of pressure needed to move the melting point of Thorium Dioxide up by 444 degrees kelvin using the Clausius-Clapeyron Law to see whether it would be feasible to line the combustion chamber of...

Homework Statement A 42kg block of ice at 0°C is sliding on a horizontal surface. the initial speed of the ice is 7.3 m/s and the final speed is 3.5m/s. Assume that the part of the block that melts has a very small mass and that all the heat generated by kinetic friction goes into the block...

Homework Statement We completed a lab with the following information Substance Mass(g) Starting temperature (°C) Final Temperature (°C) Ice cube 15.55 0 12 Water 151.25 21 12 Now...

Homework Statement The definition of latent best of vapourization is the amount of thermal energy required to change the state of a liquid to a gas or vice versa. Also, when we increase the pressure of the gas on the liquid there has to be more work done against the surroundings so the latent...

I am having confusion with the difference between these two, or are they synonymous terms?

Homework Statement A pupil performing an experiment finds that, when the heat supply is 16W, it takes 30 mins for the temp of the water to rise from 20°C to 100°C, and that the rate of evap is very slow even at the latter temp. Estimate an upper limit to the value of the heat capacity of the...

The graph is in the attachment! ( don't have to download to view the file)Homework Statement 49a) A 0.25 kg piece of ice is warmed by an electric heater and the following graph of temperature is produced. Assume that there has been no loss of energy to surroundings. How much additional time...

Homework Statement What is the total amount of heat required to heat a 0.2 kg of ice from a temperature of -20 degrees to a temperature of 30 degrees Celsius Homework Equations Q=mcΔt Q=mLf Q=mLv The Attempt at a Solution To solve this they break it down, almost like a...

Homework Statement An aluminum container whose mass is 205g contains 300g of water at 20°C. In this container is then placed 250g of iron at 150°C and 20g of ice at -10°C. Find the final temperature of the mixture. Given: mAl=205g mH2O=300g TAl1=TH2O1=20°C mFe=250g mice=20g TFe=150°C...

Homework Statement 10g of ice at 0 degrees Celcius is combined with 2 g of steam at 100 degrees Celcius. Find the final temperature of the resulting water. Homework Equations mc(Tf- Ti) m(Lf) or m (Li) The Attempt at a Solution ΔQice=mLice+mcwaterTf...

Problem solved.Homework Statement The boiling point of a certain liquid is 95OC at the top of a mountain and 105OC at the bottom. Its latent heat is 1000 cal/mole. Calculate the height of mountain. It's Q4 of chapter 15 in Statistical Mechanics by S.K. MaHomework Equations it should be the...

Doing some fun problems in Keith Stowe's 'An Introduction to Thermodynamics and Statistical Mechanics'. Good book. Problem statement: A certain material vaporizes from the liquid phase at 700 K. In both phases, the molecules have three degrees of freedom. If u_{0} in the liquid phase is...

If the melting point depends on the pressure, does the latent heat of fusion also depend on the pressure? The equation relating the entropy of fusion to the enthalpy of fusion is given by: \Delta H=T\Delta S where T is, apparently, the temperature of melting. So, if the melting point...

Homework Statement 215 cm3 of hot tea at 95°C are poured into a very thin paper cup with 40 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 0 =...

I've been having trouble understanding this second semester of physics thus far. I've done SHM pretty well, but this stuff is just strange to me. So here are the problems verbatum, but i'll fill out the template below to help ease the pains. For problem 1: Homework Statement The heating...

Why is the latent heat of vaporisation greater than that of fusion(melting)? I mean in liquid state,atoms are already far apart, so it must require less energy to make them gas(far apart) as forces(electric in nature) between molecules decrease with distance.

A 3 kW kettle contains 2.0 kg of water at a temperature close to 100oC. Latent heat of vaporisation for water: Lv=2256 (kJ kg^-1) Q= Lv x mass Ok I understand this problem because I now the answer but I don't understand the process. Like my teacher wrote 2256x10^3 why he wrote...

Homework Statement For the problem below I was able to work out part (i) but I am stuck on working out part (ii) I tried using information given but was unsuccessful. Can anyone help me out? An insulated copper container of mass 0.250 kg contains 0.350 kg water. Both the container and the...

Homework Statement one gram of ice at 0 degree C contracts in volume by 0.091cc on melting. 9gm of a metalis heated to 200 degree C and dropped into and ice calorimeter. The decrease in volume was found to be 0.0182 cc. Calculate the Sp. heat of the metal (ANS:0.09cal/gmC) Homework...

Specific & Latent Heat - Heat required to turn water in Aluminum Tray --> Ice Homework Statement 200 g Water (l) is contained in an Aluminum ice tray that has a mass of 340 g. Both is at 18°C. How much heat (Q) must be removed to turn the water into ice at -15°C? Aluminum mAl= 340g...