20. Heat and Temperature

Calorimetry with Temperature and Phase Changes

Open Question
. A vessel whose walls are thermally insulated contains 2.40 kg of water and 0.450 kg of ice, all at 0.0°C. The outlet of a tube leading from a boiler in which water is boiling at atmospheric pressure is inserted into the water. How many grams of steam must condense inside the vessel (also at atmospheric pressure) to raise the temperature of the system to 28.0°C? You can ignore the heat transferred to the container.
Open Question
A 4.00-kg silver ingot is taken from a furnace, where its temperature is 750.0°C, and placed on a large block of ice at 0.0°C. Assuming that all the heat given up by the silver is used to melt the ice, how much ice is melted?
Open Question
An insulated beaker with negligible mass contains 0.250 kg of water at 75.0°C. How many kilograms of ice at -20.0°C must be dropped into the water to make the final temperature of the system 40.0°C?
Open Question
A laboratory technician drops a 0.0850-kg sample of unknown solid material, at 100.0°C, into a calorimeter. The calorimeter can, initially at 19.0°C, is made of 0.150 kg of copper and contains 0.200 kg of water. The final temperature of the calorimeter can and contents is 26.1°C. Compute the specific heat of the sample
Open Question
An asteroid with a diameter of 10 km and a mass of 2.60*10^15 kg impacts the earth at a speed of 32.0 km/s, landing in the Pacific Ocean. If 1.00% of the asteroid's kinetic energy goes to boiling the ocean water (assume an initial water temperature of 10.0°C), what mass of water will be boiled away by the collision? (For comparison, the mass of water contained in Lake Superior is about 2*10^15 kg.)
Open Question
An ice-cube tray of negligible mass contains 0.290 kg of water at 18.0°C. How much heat must be removed to cool the water to 0.00°C and freeze it? Express your answer in joules, calories, and Btu
Open Question
A 65 cm^3 block of iron is removed from an 800°C furnace and immediately dropped into 200 mL of 20°C water. What fraction of the water boils away?
Open Question
10 g of steam at the boiling point are combined with 50 g of ice at the freezing point. What is the final temperature of the system?
Open Question
(II) High-altitude mountain climbers do not eat snow, but always melt it first with a stove. To see why, calculate the energy absorbed from your body if you

(a) eat 1.0 kg of -15°C snow which your body warms to body temperature of 37°C;
Open Question
(I) How much heat is needed to melt 26.50 kg of silver that is initially at 25°C?
Open Question
(I) If 3.40 x 10⁵ J of energy is supplied to a container of liquid oxygen at -183° C , how much oxygen can evaporate?
Open Question
(II) At a crime scene, the forensic investigator notes that the 6.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact. Assuming the bullet was shot at room temperature (20°C), what does the investigator calculate as the minimum muzzle velocity of the gun?
Open Question
"(II) An iron boiler of mass 180 kg contains 710 kg of water at 18°C. A heater supplies energy at the rate of 58,000 kJ/h. How long does it take for the water

(a) to reach the boiling point, and "
Open Question
(II) During exercise, a person may give off 185 kcal of heat in 25 min by evaporation of water (at 20°C) from the skin. How much water has been lost? [Hint: See page 548.]
Open Question
An iron meteorite melts when it enters the Earth’s atmosphere. If its initial temperature was -105° C outside of Earth’s atmosphere, calculate the minimum velocity the meteorite must have had before it entered Earth’s atmosphere.