QUANTITY OF HEAT.
SPECIFIC HEAT.
First level
1. What will require more heat for heating by 1°C:
a glass of water or a can of water?
Answer: Q \u003d cm (t 2 -t 1)
the mass of a can of water is greater,
so more heat is needed to heat up
2. What will require more heat to heat up by 1 ° C:
100 g of water or 100 g of copper?
Answer: Q \u003d cm (t 2 -t 1)
The specific heat capacity of water is higher (4200, 400),
so more heat is needed to heat the water
3. Which substance has the smallest specific heat?
Answer: air (?)
4. Which substance has the highest specific heat capacity?
Answer: water (?)
5. What amount of heat is needed to heat iron weighing 1 g by 1 ° C?
Answer: Q \u003d cm (t 2 -t 1)
Q=460. 0.001 . 1 = 0.46 J
6. It takes 230 J to raise the temperature by 1°C for 1 kg tin. What is the specific heat capacity of tin?
7. An aluminum part weighing 1 kg cools down by 1°C. How much heat is released when the part cools?
Answer: Q \u003d cm (t 2 -t 1)
Q=920. 1 . 1 = 920 J
8. Cast iron part weighing 1 kg was heated to 1°C. By how much did it increase internal energy details?
Answer: Q \u003d cm (t 2 -t 1)
ΔU=Q=540. 1 . 1 = 540 J
1. How much heat can be used to heat 0.3 kg of water from 12°C to 20°C?
m=0.3 kg
t 1 \u003d 12 ° С
t 2 \u003d 20 ° С
c=4200
Q=?
Q \u003d cm (t 2 -t 1)
Q=4200. 0.3 . (20-12) = 10080 J
2. What mass of water can be heated by 10°C with 1 kJ of heat?
t 2 -t 1 \u003d 10 ° С
Q \u003d 1 kJ 1000J
c=4200
m=?
Q \u003d cm (t 2 -t 1)
3. How many degrees did the boiling water cool down in a drinking tank with a capacity of 27 liters,
if he gave environment 1500 kJ of heat?
V= 27 l 0.027 m 3
Q \u003d 1500 kJ 1500000J
c=4200
ρ=1000 
Q \u003d cm (t 2 -t 1)
4. It takes 9.1 kJ to heat 110 g of aluminum by 90°C.
Calculate the specific heat capacity of aluminum.
m=110g 0.11kg
t 2 -t 1 \u003d 90 ° С
Q=9.1 kJ 9100J
5. How much heat is needed to heat a 200 g brass weight
from 20 to 28°C?
m=200g 0.2kg
Q \u003d cm (t 2 -t 1)
Q=400. 0.2 . (28-20) = 640 J
6. What is the mass of the iron part, if it went to heating from 20 ° C to 200 ° C
20.7 kJ of heat?
t 2 \u003d 200 ° C
Q \u003d 20.7 kJ 20700000J
Q \u003d cm (t 2 -t 1)
7. By how many degrees did the temperature of 4 liters of water increase if it received an amount of heat equal to 168 kJ?
V= 4 l 0.004 m 3
Q \u003d 168 kJ 168000J
c=4200
ρ=1000
Q \u003d cm (t 2 -t 1)
8. An ingot of silver weighing 120 g, when cooled from 66 ° C to 16 ° C, transferred 1.5 kJ of heat to the environment. What is the specific heat capacity of silver?
m=120g 0.12kg
Q=1.5 kJ 1500J
1. A) Why is it hot in deserts during the day, but at night the temperature drops below 0°C?
b) To cool a piece made of copper, having a temperature of 100°C, it was immersed in 420 g of water at a temperature of 15°C. Determine the mass of the part if it is known that during the heat exchange process the water is heated to 18°C.
2. A) A piece of lead and a piece of steel of the same mass were struck with a hammer the same number of times. Which piece got hotter? b) A piece of steel weighing 300 g is heated to high temperature, and then immersed for hardening in 3 kg of machine oil having a temperature of 10°C. Determine the initial temperature of the part if the temperature at steady state thermal equilibrium was 30°C.
3. A) Why do iron stoves heat up a room faster than brick stoves, but do not stay warm for so long? b) An aluminum calorimeter weighing 140 g was filled with 250 g of water at a temperature of 15°C. After a lead bar weighing 100 g, heated to 100°C, was placed in a calorimeter with water, a temperature of 16°C was established there. Write an equation heat balance and determine the specific heat capacity of lead.
4. A) Why are rivers and lakes warming up? sunbeams slower than land?
b) The boy filled a glass, the capacity of which is 200 cm 3, with boiling water for three quarters and added to the glass cold water. Determine which one is installed water temperature if the cold water temperature is 20°C.
5. A) Copper and steel weights of the same mass were given equal amounts warmth. Which weight will change the temperature the most? b) The steel product was hardened by heating to a temperature of 800°C, followed by immersion in oil weighing 2 kg, taken at a temperature of 10°C. At the same time, the oil was heated to a temperature of 40°C. Find the mass of the steel product if the product is cooled by 20°C during transfer to oil. The specific heat capacity of the oil is 2100 J/(kg °C).
6. A) What is more efficient to use as a heating pad - 2 kg of water or 2 kg of sand at the same temperature? b) To prepare a bath with a capacity of 200 liters, mixed cold water at a temperature of 10°C with hot at a temperature of 60°C. What volumes of both waters must be taken in order to establish a temperature of 40 ° C?
7. A) What is spent on more energy: for heating water or an aluminum pan, if their masses are the same? b) Water weighing 150 g, poured into a brass calorimeter weighing 200 g, has a temperature of 12°C. Find the temperature that will be established in the calorimeter if an iron weight of 0.5 kg heated to 100°C is lowered into water.
8. A) In which case hot water cooler in a glass: if a silver or aluminum spoon of the same mass is lowered into it? Justify the answer. b) Mixed 39 l of water at 20°C and 21 l of water at 60°C. Determine the temperature of the mixture.
1. Mixed 6 kg of water at 42°C, 4 kg of water at 72°C and 20 kg of water at 18°C. Determine the temperature of the mixture.
2. 150 g of water was poured into an aluminum vessel weighing 45 g at a temperature of 20°C. A cylinder weighing 200 g, the temperature of which is 95°C, is lowered into the vessel, while the water temperature rises to 30°C. Determine the specific heat capacity of the substance from which the cylinder is made.
3. In 200 g of water at 20°C, place 300 g of iron at 10°C and 400 g of copper at 25°C. Find the steady temperature.
4. A metal cylinder weighing 146 g heated to 100°C is lowered into a brass calorimeter weighing 128 g containing 240 g of water at a temperature of 8.5°C. As a result of heat exchange, a temperature of 10°C was established. Determine the specific heat capacity of the cylinder metal.
5. A 200 g brass vessel contains 400 g of aniline at a temperature of 10°C. In the vessel was added 400 g of aniline, heated to a temperature of 31°C. Find the specific heat capacity of aniline if the temperature in the vessel is 20°C.
6. In what ratio should the volumes of lead and tin be taken so that their heat capacities are the same?
7. An iron calorimeter weighing 100 g contains 500 g of water at a temperature of 15°C. Lead and aluminum are thrown into the calorimeter total weight 150 g and a temperature of 100°C. As a result, the water temperature rises to 17°C. Determine the masses of lead and aluminum.
8. After lowering into water having a temperature of 10°C, a body heated to 100°C, after a while, a general temperature of 40°C was established. What will be the temperature of the water if, without taking out the first body, another similar body heated to 100°C is lowered into it?
1. Why do the scattered coals of a fire go out quickly, and those piled up in a heap remain in a red-hot form for a long time?
2. With the complete combustion of 500 g of fuel, 22 MJ of heat was released. What is this fuel? (44 MJ/kg)
3. How many degrees will 3 kg of water heat up if all the heat released during the complete combustion of 10 g of alcohol went to heat it? (21.4 0)
4. How much alcohol must be burned to change the temperature of water weighing 2 kg from 14 0 to 50 0 if all the heat released by alcohol goes to heat the water? (11 g)
5. How much firewood must be burned in order to heat 50 liters of water in an iron cauldron weighing 10 kg from 15 0 to 65 0? Ignore heat loss. (1.1 kg)
6. How much water can be heated from 10 0 to 60 0, burning 40 kg hard coal if the efficiency of the heater is 40%?
7. How much water can be heated with a boiler from 10 0 to boiling, burning 600 g of birch firewood, if 25% of the heat released during the combustion of firewood went to heat the water? (4 kg)
8. A stone falls from a height of 250 m into the gorge. Due to friction against the air and hitting the ground, the stone heats up by 1.5 degrees. Determine the specific heat capacity of the stone, assuming that only 50% of the energy of the stone went into heating it. (817 J / kg * 0 C)
9. Mixed 6 kg of water at 42 0, 4 kg at 72 0 and 20 kg at 18 0. Determine the temperature of the mixture. (30 0 С)
10. 150 g of water was poured into an aluminum vessel weighing 45 g at a temperature of 20 0 C. A cylinder weighing 200 g was lowered into the vessel, the temperature of which was 95 0 C, while the water temperature increased to 30 0 C. Determine the specific heat capacity of the substance from which the cylinder is made . (516 J/kg* 0 С)
11. In 1813, on one of the tributaries of the Ural River Iset, where poor gold-bearing quartz veins were mined, a young girl Katya Bogdanova found a large platinum nugget and brought it to the clerk. What is the mass of a platinum nugget found in the Urals in 1904, if for heating it by 20 °C would require 23,056 J of energy? The specific heat capacity of platinum is 0.14 kJ / (kg? K).
Answer: 8.395 kg.
12. Russia, year 1842, October 8. At the Tsarevo-Aleksandrovsky mine near the city of Miass, which is on Southern Urals, found a gold nugget weighing 36 kg 16 g. Now " big triangle"- this is how the unique specimen was called - can be seen in the Diamond Fund of the Moscow Kremlin. It is considered the largest surviving in the world. How many degrees will it heat up if it receives 18,720 J of heat? The specific heat of gold is 0.13 kJ / (kg K) .
Answer: 4 °C.
13. The "Hare Ears" nugget has a mass of 3,344.3 g. What is the volume of this nugget?
14. The world's largest gold nugget was found in Australia in 1872 at the Hill End mine. The nugget had the shape of a slab 144 cm long, 66 cm wide and 10 cm thick. The nugget was called the "Holterman Slab". What is the mass of a nugget?
15. In 1992, a silver nugget weighing 30 kg was found in Khakassia. What is the specific heat capacity of silver if 294 kJ of energy is released when a nugget is cooled from 80 to 10 °C?
Answer: 0.14 kJ/(kg K).
16. In 1986, the largest topaz crystal was found in Brazil. Its mass is 8 tons, dimensions are 2? 1.4? 3 m. What is the density of topaz?
17. How much does the internal energy of the Tsar Cannon with a mass of 40 tons change at the maximum temperature drop recorded in Moscow from + 36 ° C to - 42.2 ° C? The specific heat capacity of the metal is 0.45 kJ/(kg K).
Answer: 1420 MJ.
18. To what temperature does the soil in Uzbekistan heat up if the internal energy of each cubic meter changes by 93.744 MJ? The initial temperature of the soil is 17 °C, the density of the soil is 1800 kg/m3, and its specific heat capacity is 0.84 kJ/(kg K).
Answer: 79 °C.
19. The highest soil temperature in Turkmenistan reaches 77 °C. What is the initial temperature of a giant chicken egg weighing 420 g, registered in 1977 in Kyrgyzstan, if it received 40 kJ of energy when it was covered with hot sand? The specific heat capacity of the contents of the egg is 2 kJ/(kg K).
Answer: 27 °C.
20. In 1879, a monolith of malachite weighing 1054 kg was found in the Urals. By how much did its internal energy change if the temperature increased by 20 °C during transportation?
Answer: 25.3 MJ.
21. A unique find weighing 2480 g is stored in the Kaliningrad Amber Museum. How much has the internal energy of this piece changed when it was transferred to the museum, if the water temperature in the Baltic Sea is 10 ° C, and in the museum 20 ° C? The specific heat capacity of amber is 2 kJ/(kg K).
Answer: by 85.6 kJ.
22. What is the mass of a piece of amber stored in Palanga if its energy increased by 93.6 kJ when the temperature changed from 5 to 18 °C?
Answer: 3600
23. The largest topaz weighing 117 kg was found in Ukraine in 1965. How will its internal energy change during winter transportation from Moscow to Paris, if the average temperatures in these cities are -10 °С and +3.5 °С, respectively? The specific heat capacity of the stone is 0.84 kJ/(kg K).
Answer: increase by 1.33 MJ.
24. What is the temperature of the water in the hottest lake in Kamchatka, if 40 liters of water at 10 °C are poured into it to prepare a 200-liter bath at a temperature of 40 °C?
Answer: 50 °C.
25. What is the summer water temperature in the coldest East Siberian Sea, if 2 liters of boiling water must be added to it to get 10 m3 of water at a temperature of 20 ° C?
Answer: 0 °C.
26. In 1968, a large hail fell in Blagoveshchensk, and at a temperature of 0 ° C, the mass of one hailstone was 400-600 g. How much alcohol must be burned to get water from it at 20 ° C? Ignore losses. The specific heat of combustion of alcohol is 27 MJ/kg.
Answer: 6.1-9.2 g.
27. In 1965, hail fell in Kislovodsk, which covered the soil with a layer 75 cm thick. How much has the internal energy of each square meter when it melts? The bulk density of the substance is 800 kg/m3.
Answer: 198 MJ.
28. In 1843, a platinum nugget weighing 9636 g was found in the Urals.
What is the melting point of platinum if 3466 kJ of heat was used to melt it? The specific heat capacity of platinum is 140 J/(kg* K), the specific heat of fusion is 113 kJ/kg, the initial temperature is 10°C
Answer: 1770 °C.
29. Russian master Chokhov in the 17th century. cast a bell weighing 35 tons. How much heat was required to prepare the melt if the initial temperature of the metal was 20 °C? The specific heat capacity of the alloy is 0.4 kJ/(kg K), the melting point is 1100°C, and the specific heat of melting is 213 J/g.
Answer: 2260 MJ.
30. The gold nugget "Horse's Head" is kept in the Kremlin's Diamond Fund. What is the mass of the nugget if 938 kJ of heat would be required for its complete melting?
Answer: 14 kg.
31. The Camel gold nugget has a mass of 9.3 kg and a temperature of 15 °C. What is the melting point of gold if 1892 kJ of heat would be required for remelting?
Answer: 1064 °C.
32. During excavations in Alushta in 1990, 17 silver ingots were found with a total weight of 3.5 kg at a temperature of 5 °C. What is the specific heat of fusion of silver if 254 g of gas with a specific heat of combustion of 45 MJ/kg was required for remelting? Ignore losses.
Answer: 87 kJ / kg.
33. What is the most low temperature registered on arctic station"Vostok", if 200 ml of water at a temperature of 15 ° C, taken out of the room and left overnight, released 105,714 J of energy?
Answer: -89.2 °C.
34. What is the lowest air temperature in the region of the Indigirka River, if it was necessary to burn 6 kg of diesel fuel, the specific heat of combustion of which is 42.7 MJ / kg, to obtain water at 18 ° C from a piece of ice with a volume of 0.5 m3?
Answer: -78 °C.
35. A samovar made in Tula in 1922 had a capacity of 250 liters. How long did it take to boil with the burning of 600 g of firewood every minute? The initial water temperature is 10 °C, the efficiency is 40%, the specific heat of combustion of firewood is 10 MJ/kg.
Answer: 40 min.
36. What capacity did the new Tula record-breaking samovar have if, at an efficiency of 50%, it boiled in 20 minutes and consumed 460 g of charcoal every minute, the specific heat of combustion of which was 35 MJ / kg? The initial water temperature is 15 °C.
Answer: 450 liters.
37. How much charcoal should be burned to boil water in a 50 liter Suksun samovar if the initial water temperature is 20°C? Specific heat combustion of charcoal 35 MJ/kg?
Answer: 0.48kg
38. The most economical heat engine in 1840 consumed 0.77 kg of coal at a power of 735 watts. What is the efficiency of the installation? The specific heat of combustion of coal is 29 MJ/kg.
Answer: 12%.
39. The largest American boiler with a capacity of 1330 MW produces 4,232,000 kg of steam per hour. What is the efficiency of the installation if water enters it at 20 ° C?
Answer: 50%.
40. The most powerful diesel engine in Switzerland has a power of 41,920 kW. How much fuel per hour does it consume during operation if its efficiency is 35%? The specific heat of combustion of the fuel is 42 MJ/kg.
Answer: 10.3 tons.
41. The diesel engine of the KamAZ-5350 Mustang has a power of 191.36 kW. How much fuel per hour does it consume during operation if its efficiency is 35%? The specific heat of combustion of the fuel is 42 MJ/kg.
Answer: 46.86 kg
42. The largest oil tanker has a capacity of 1.5 million barrels (1 barrel = 158.988 liters). How much heat is released during the complete combustion of oil? The specific heat of combustion of oil is 43 MJ/kg, the density is 0.8 t/m3.
Answer: 1015 J.
· We create our own website.
First level
1. What will require more heat to raise 1°C: a glass of water or a can of water?
2. What will require more heat to raise 1°C: 100 g of water or 100 g of copper?
3. Which substance has the lowest specific heat capacity?
4. Which substance has the highest specific heat capacity?
5. What amount of heat is needed to heat iron weighing 1 g by 1 ° C?
6. It takes 230 J to raise the temperature by 1°C for 1 kg tin. What is the specific heat capacity of tin?
7. An aluminum part weighing 1 kg cools down by 1°C. How much heat is released when the part cools?
8. Cast iron part weighing 1 kg was heated to 1°C. By how much did the internal energy of the part increase?
Average level
1. How much heat can be used to heat 0.3 kg of water from 12°C to 20°C?
2. What mass of water can be heated by 10°C with 1 kJ of heat?
3. By how many degrees did boiling water cool down in a drinking tank with a capacity of 27 liters if it gave off 1500 kJ of heat to the environment?
4. It takes 9.1 kJ to heat 110 g of aluminum by 90°C. Calculate the specific heat capacity of aluminum.
5. How much heat is needed to heat a 200 g brass weight from 20 to 28°C?
6. What is the mass of an iron part if 20.7 kJ of heat was used to heat it from 20°C to 200°C?
7. By how many degrees did the temperature of 4 liters of water increase if it received an amount of heat equal to 168 kJ?
8. An ingot of silver weighing 120 g, when cooled from 66 ° C to 16 ° C, transferred 1.5 kJ of heat to the environment. What is the specific heat capacity of silver?
Enough level
1. a) Why is it hot in deserts during the day, but at night the temperature drops below 0°C? b) In order to cool a piece made of copper, having a temperature of 100°C, it was immersed in 420 g of water at a temperature of 15°C. Determine the mass of the part if it is known that during the heat exchange process the water is heated to 18°C.
2. a) A piece of lead and a piece of steel of the same mass were hit with a hammer the same number once. Which piece got hotter?
b) A steel piece weighing 300 g was heated to a high temperature, and then immersed for quenching in 3 kg of machine oil having a temperature of 10°C. Determine the initial temperature of the part, if the temperature at steady state thermal equilibrium was 30°C.
3. (a) Why do iron stoves heat a room faster than brick stoves, but do not stay warm for so long? b) 250 g of water are poured into an aluminum calorimeter weighing 140 g at a temperature of 15°C. After a lead bar weighing 100 g, heated to 100°C, was placed in a calorimeter with water, a temperature of 16°C was established there. Write a heat balance equation and determine the specific heat capacity of lead.
4. a) Why are rivers and lakes heated by the sun's rays more slowly than land? b) The boy filled a glass with a capacity of 200 cm 3 with boiling water three quarters and added cold water to the glass. Determine what the water temperature is when the cold water temperature is 20°C.
5. a) Equal amounts of heat were transferred to copper and steel weights of the same mass. Which weight will change the temperature the most? b) The steel product was hardened by heating to a temperature of 800°C, followed by immersion in oil weighing 2 kg, taken at a temperature of 10°C. At the same time, the oil was heated to a temperature of 40°C. Find the mass of the steel product if the product is cooled by 20°C during transfer to oil. The specific heat capacity of the oil is 2100J/(kgּ°С).
6. a) What is more efficient to use as a heating pad - 2 kg of water or 2 kg of sand at the same temperature? b) To prepare a bath with a capacity of 200 liters, cold water at a temperature of 10°C was mixed with hot water at a temperature of 60°C. What volumes of both waters must be taken in order to establish a temperature of 40 ° C?
7. a) What uses more energy: heating water or an aluminum pan if their masses are the same? b) Water weighing 150 g, poured into a brass calorimeter weighing 200 g, has a temperature of 12°C. Find the temperature that will be established in the calorimeter if an iron weight of 0.5 kg heated to 100°C is lowered into water.
8. a) In which case will hot water in a glass cool more: if a silver or aluminum spoon of the same mass is lowered into it? Justify the answer. b) Mixed 39 l of water at 20°C and 21 l of water at 60°C. Determine the temperature of the mixture.
High level
1. Mixed 6 kg of water at 42°C, 4 kg of water at 72°C and 20 kg of water at 18°C. Determine the temperature of the mixture.
2. 150 g of water was poured into an aluminum vessel weighing 45 g at a temperature of 20°C. A cylinder weighing 200 g, the temperature of which is 95°C, is lowered into the vessel, while the water temperature rises to 30°C. Determine the specific heat capacity of the substance from which the cylinder is made.
3. In 200 g of water at 20°C, place 300 g of iron at 10°C and 400 g of copper at 25°C. Find the steady temperature.
4. A metal cylinder weighing 146 g heated to 100°C is lowered into a brass calorimeter weighing 128 g containing 240 g of water at a temperature of 8.5°C. As a result of heat exchange, a temperature of 10°C was established. Determine the specific heat capacity of the cylinder metal.
