1. A 150 W immersion heater is used to keep the water in a large beaker boiling under standard atmospheric pressure. In 5 minutes, 16 g of water boils away. Neglect any heat loss to surroundings. (a) Find the specific latent heat of vaporization of water, I. A student puts a small metal sphere in the boiling water. After a few minutes, the sphere is quickly transferred to a polystyrene cup containing 100 g of water at a temperature of 20 °C. The cup of water is stirred gently and its highest temperature attained is 22 °C. Given: specific heat capacity of water-4200 J kg-¹ °C- (b) Estimate the heat capacity C of the metal sphere. (e) In fact the sphere has carried with it some boiling water to the cup of water. Referring to this fact, explain whether the true value of C is higher or lower than the value calculated in (b).

1. A 150 W immersion heater is used to keep the water in a large beaker boiling under standard atmospheric pressure. In 5 minutes, 16 g of water boils away. Neglect any heat loss to surroundings. (a) Find the specific latent heat of vaporization of water, I. A student puts a small metal sphere in the boiling water. After a few minutes, the sphere is quickly transferred to a polystyrene cup containing 100 g of water at a temperature of 20 °C. The cup of water is stirred gently and its highest temperature attained is 22 °C. Given: specific heat capacity of water-4200 J kg-¹ °C- (b) Estimate the heat capacity C of the metal sphere. (e) In fact the sphere has carried with it some boiling water to the cup of water. Referring to this fact, explain whether the true value of C is higher or lower than the value calculated in (b).

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter9: Heat Transfer With Phase Change

Section: Chapter Questions

Problem 9.4DP

See similar textbooks

Similar questions

A cylindrical liquid oxygen (LOX) tank has a diameter of 1.22 m, a length of 6.1 m, and hemispherical ends. The boiling point of LOX is -179.4C. An insulation is sought that will reduce the boil-off rate in the steady state to no more than 11.3 kg/h. The heat of vaporization of LOX is 214 kJ/kg. If the thickness of this insulation is to be no more than 7.5 cm, what would the value of its thermal conductivity have to be?
During processing in a steel mill, a 375kg steel casting at 800 degrees is quenched by plunging it into a 500-gal oil bath, which is initially 75 degrees . After the casting cools and the oil bath warms , what is the final tempertature of the two? The weight per unit volume of the oil is 7.5 lb/gal.
Consider the heating of water in a pan on a top of a range. If 24 kJ of heat is transferred to the water from heating element and 6 kJ of it is lost from the water to the surrounding air. Determine;(a) the net heat transfer to the water,(b) the efficiency for boiling water.
2) Two glass bulbs, one on the left with a volume of 2 liters and the other on the right with avolume of 6 liters, are connected to one another by a thin tube that is initially closed by astopcock. The bulb on the left has 0.1 moles of ideal gas, and the bulb on the right isevacuated. The system is in thermal equilibrium with the surroundings at 300K. When thestopcock is opened, the gas flows out to fill both bulbs. Calculate A for this process. If wewere to insert a propeller to extract work as the gas flows from left to right, what is themaximum amount of work that we could possibly extract?
7. A pan made of stainless steel contains water at atmospheric pressure. The pan diameter is 25 cm and its surface is mechanically polished. The pan is now heated while its surface is maintained at 116 C. Find the surface heat flux, the boil off (evaporation) rate, and the peak heat flux
Draw a VLLE diagram when the temperature is constant.
What refrigeration capacity in TOR is required to cool 2000 cfm of air from 85°F to 70°F? If the specific heat ratio (k) and specific gas constant (R) of air are 1.4 and 0.28708 kJ/kg-K, respectively.
determine the require heat in BTU, for the water at 50degrees celsius to become ice at -50 degrees celsius
Assume that cream has a specific heat of 2900 J/kg· ◦C and has the same heat of fusion (3.34 × 105 J/kg) and melting point as water, and that ice cream has a specific heat of 2200 J/kg· ◦C. If two kilograms of cream are initially at 10◦C, how much liquid nitrogen, which has a latent heat of vaporization of 2.00 × 105 J/kg, must be vaporized to cool, freeze, and further cool the cream to -10◦C? Assume that the liquid nitrogen is kept at 77 K, the temperature of its liquid-gas phase transition, and that the gas floats away into the room at that temperature (so no heat goes to heating up the nitrogen gas).
Consider a glass of ice water at 0 °C. Moisture from the air is observed to condense on the outer sides of the glass. This condensation causes the ice in the glass to melt faster than if there were no condensation. For this problem use LvLv= 2430 kJ/kg for the latent heat of vaporization of water at 37 °C as a better approximation than LvLv for water at 100 °C.) Determine the mass of ice, in grams, in the glass that would melt as a result of the condensation of 6.6 g of water from the air onto the sides of the glass.
Five kg of water vapour are contained at 150 kPa ad 90 per cent quality in asuitable enclosure. Calculate the heat which must be added in order to justproduce a saturated vapor. What will the pressure be at the end of theheating process?
When an ice is being heat up, it will undergo a series of thermodynamic process. Explain with a diagram that how ice will undergo latent heat of fusion, latent heat of vaporization and temperature changes under heat transfer process.