"Specific Heat Capacity" Content PPT

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"Specific Heat Capacity" Content PPT

Part One: Guidance Design

Learning point 1 Specific heat capacity

Experiment: Assemble the experimental equipment as shown in Figure 13-3-5. The two test tubes are filled with water and kerosene of the same quality respectively. The test tubes are fixed by a wire bracket and are not in contact with the bottom of the container. Light the alcohol lamp to heat the water in the large beaker. Read the temperature of the water and kerosene in the test tube at the same time and record it. The data obtained are as shown in the following table:

Learning point 2 Calculation of heat

If you know the specific heat capacity of a substance, you can calculate how much heat a certain mass of the substance absorbs or releases when it raises or lowers a certain temperature. For example: the specific heat capacity of copper is 0.39×103 J/(kg·℃), which means that the heat absorbed by 1 kg of copper when its temperature rises by 1 ℃ is 0.39×103 J. Then put a copper with a mass of 2 kg and a temperature of 30 ℃. When the block is heated to 100 ℃, the heat absorbed is Q=0.39×103 J/(kg·℃)×2 kg×(100 ℃-30 ℃)=5.46×104 J.

think:

Question 1: Based on the above information, can you summarize the calculation formula for the heat absorbed by an object?

answer:_________________.

Question 2: What is the formula for calculating the heat released by an object?

answer:___________________.

Specific heat capacity PPT, part 2: summary of common exams

Type 1 The concept of specific heat capacity

Typical Example 1 [Bazhong High School Entrance Examination] The following are the specific heat capacities of some substances:

According to the data in the table, which of the following is correct? ()

A. The specific heat capacity of 1 kg of aluminum is 12 of the specific heat capacity of 2 kg of aluminum

B． Most cooling towers in factories use water as the coolant to take advantage of water's large specific heat capacity.

C. The specific heat capacity of a substance has nothing to do with the state of the substance

D. Water and kerosene of equal mass absorb the same amount of heat, but the temperature of the water changes greatly.

Type 2 Related calculations of specific heat capacity

(1)Image problem

Typical Example 2 In the experiment of "Exploring the Endothermic Capacity of Materials", Xiao Ming put two liquids A and B with the same mass into two identical beakers, and heated them simultaneously with two identical alcohol lamps. Two identical thermometers measure the temperature of the liquid in the beaker respectively, and create an image of the liquid temperature changing with time. The relationship is shown in Figure 13-3-6. [cWater=4.2×103 J/(kg·℃)]

(1) From the analysis of the image, it can be seen that ______ liquid has a strong ability to absorb heat.

(2) If one of the two liquids A and B is water, then the specific heat capacity of the other liquid is ________J/(kg·℃).

(2) Heat calculation

Typical Example 3 A red-hot iron nail has a temperature of 500 ℃ and a mass of 1.5 g. How much heat will be released when its temperature is reduced to 20 ℃? [cFe=0.46×103 J/(kg·℃)]

(3) Comparison problem

Typical Example 4 The mass ratio of two metal balls A and B is 5:3. After absorbing the same heat, the ratio of the rising temperatures is 1:5, then the ratio of their specific heat capacities is cA:cB=______.

Type 3 Application of Specific Heat Capacity

Typical Example 5 Figure 13-3-8 shows the temperature change curves of a coastal city and an inland city on the same day. Please judge whether the curve corresponding to the daily temperature change in inland cities is ______ (optional "A" or "B"). This is due to the specific heat capacity of sand and gravel ______ (optional "greater than", "less than" or "equal to" ) The specific heat capacity of water, the temperature change after absorbing the same amount of heat ______ (optional "large" or "small").

Specific heat capacity PPT, part 3 content: Class feedback A

1. When Xiao Ming and Xiao Hua did the experiment of "comparing the speed of temperature rise when water and kerosene absorb heat", they used the device shown in Figure 3-1.

(1) When designing the experimental plan, they determined the following variables to be controlled, of which the redundant ones are ( )

A. Use exactly the same heating method B. The amount of alcohol added to the alcohol lamp is the same

C. Take the same mass of water and kerosene D. Containers for water and kerosene are the same

(2) In this experiment, the purpose of using exactly the same heating method is to make water and kerosene _______________ in the same time.

(3) When water and kerosene absorb the same amount of heat, determine the strength of their heat absorption capabilities by comparing ____________________.

2. The unit of specific heat capacity is __________, pronounced as ____________. The specific heat capacity of water is ____________, and its physical meaning is ______________________________________________. The specific heat capacity of hot water ________ the specific heat capacity of cold water. The specific heat capacity of 1 kg of water ________ the specific heat capacity of 3 kg of water. (Please fill in the last two blanks with "greater than", "less than" or "equal to")

3. Specific heat capacity is a physical quantity that reflects the _________ ability of a substance. It is further understood that it is a physical quantity that reflects the temperature change after a substance absorbs (releases) heat. Different objects of the same mass have higher specific heat capacities, and the greater the temperature change when absorbing (releasing) the same heat. Small.

4. It can be seen from the following specific heat capacity table that when kerosene and water of equal mass raise the same temperature, ________ absorbs more heat; when aluminum and copper blocks of equal mass release the same heat, ________ decreases the temperature more.

Specific heat capacity PPT, part 4 content: Class feedback B

1. The formula for absorbing heat is Qabsorb=cm(t-t0), and the formula for releasing heat is Qdischarge=cm(t0-t), where t0 refers to the ________ of the object and t refers to the ________ of the object. The applicable conditions for the two formulas: when no change in physical state occurs, all objects with a temperature of ________ must be calculated using the endothermic formula; all objects with a temperature of ________ must be calculated with the exothermic formula.

2. The heat released by a cup of water from 80 ℃ to 20 ℃ is Q1, and the heat absorbed by this cup of water from 30 ℃ to 70 ℃ is Q2, then ( )

A. Q1＜Q2 B. Q1>Q2

C. Q1＝Q2 D. Can't compare

3. Water has the characteristic of large specific heat capacity. Which of the following phenomena has nothing to do with this characteristic is ()

4. It is known that the specific heat capacity of kerosene is 2.1×103 J/(kg·℃), and the existing kerosene has a mass of 2 kg and an initial temperature of 30 ℃. Question:

(1) When the temperature drops to 10°C, how much heat is released?

(2) When the temperature rises by 10°C, how much heat is absorbed?

5. The temperature of water with a mass of 2.2 kg is reduced by 40 ℃. Find: [It is known that c water = 4.2×103 J/(kg·℃), c aluminum = 0.88×103 J/(kg·℃)] ;

(1) How much heat is given off by water.

(2) If the heat is completely absorbed by a 12 kg aluminum block, and the initial temperature of the aluminum block is 20°C, then what is the temperature of the aluminum block after absorbing heat?

Solution: (1) The heat released by water: Q release = c water m water Δt water = 4.2×103 J/(kg·℃)×2.2 kg×40 ℃=3.696×105 J.

(2) From the question, Q absorption = Q release = 3.696 × 105 J. According to Q absorption = cm Δt deformation, the temperature of the aluminum block can be obtained: Δt = Q absorption / c aluminum m aluminum = (3.696 × 105 J) / [0.88×103 J/(kg·℃)×12 kg]=35 ℃.

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