"Studying the Specific Heat Capacity of Substances" Internal Energy and Heat Engine PPT Courseware 3

Description

"Studying the Specific Heat Capacity of Substances" Internal Energy and Heat Engine PPT Courseware 3

teaching objectives:

1. Understand the concept of specific heat capacity. Know that specific heat capacity is an attribute of matter and a physical quantity that reflects the endothermic and exothermic properties of a reaction substance. Know the unit, pronunciation and meaning of specific heat capacity.

2. Specific heat capacity to explain life phenomena, know the specific heat capacity of water, which is larger.

Detection Preview 1

The concept of specific heat capacity, know the unit, pronunciation and meaning of specific heat capacity.

life experience:

☆Compared to boiling a pot of water or boiling half a pot of water, which one takes longer?

It takes a lot of heat to boil a pot of water

☆Compared with boiling a pot of water or boiling this pot of water with warm water, which one takes longer?

It takes a lot of heat to boil water

summary:

Different substances with the same mass, raising the same temperature, absorb unequal amounts of heat.

That is, different substances have different abilities to absorb heat.

Think about it:

How to compare this property of matter?

Tip: To compare under the same conditions

To compare under the same conditions, that is, the mass must be equal and the temperature rise must be the same, and the mass is taken as unit mass (1 kilogram), and the temperature rise is measured as unit temperature rise (1°C), which is most convenient for comparison. .

Specific heat capacity: The heat absorbed by a unit mass of a substance when its temperature rises by 1°C is called the specific heat capacity of the substance, or specific heat for short.

The symbol of specific heat capacity: represented by “C”

Notice:

For unit mass of a certain substance, the heat released when the temperature decreases by 1°C is the same as the heat absorbed when the temperature increases by 1°C.

6. Exchange and cooperation

Why do seawater and sand have different temperatures at the same time?

Because seawater and sand receive sunlight for exactly the same amount of time, they absorb the same amount of heat. However, the specific heat capacity of seawater is greater than that of sand, so seawater heats up more slowly than sand. When there is no sunlight, seawater cools down more slowly than sand. Temperature changes in coastal areas are not as dramatic as in inland desert areas.

Water has a greater specific heat capacity

When water and other substances of equal mass rise (lower) to the same temperature, water absorbs (releases) more heat than other substances. (more / less)

Water with equal mass absorbs (releases) the same amount of heat as other substances, and water heats up (cools down) ___ (faster/slower) than other substances.

summary

1. The specific heat capacity of a substance is similar to the density and is also one of the physical properties of the substance. The specific heat capacity can be used to identify the type of substance.

2. For a certain substance, the specific heat capacity is a certain value, which has nothing to do with the mass of the object, the temperature change, the shape, volume, position, etc. of the object. It is only related to the type and state of the substance.

3. A substance with the same mass has a larger specific heat capacity and a larger heat absorption capacity, but the temperature changes slowly.

Give it a try:

1 Which of the following statements is correct ( )

A The higher the temperature of the object, the greater the specific heat capacity

B The greater the mass of the object, the smaller the specific heat capacity

C The more heat an object absorbs, the greater its specific heat capacity.

D The specific heat capacity of a substance has nothing to do with the mass of the object, the amount of temperature change, or the amount of heat absorbed by the object.

2 Which of the following substances has a change in its specific heat capacity ( )

A. Pour out half the glass of water.

B water freezes into ice

C water at 0°C becomes water at 4°C

D. File the iron block into iron balls

"The specific heat capacity of water is large" is of great significance in people's daily life and production.

discuss :

1. Why do car engines use water to cool them?

2. Why do radiators (commonly known as radiators) use hot water for heating in winter?

practise

In order to protect the seedlings from freezing, more water is poured into the rice field in the evening. Why is this?

Answer: This is because the specific heat of water is relatively large, and the temperature of the water in the rice field changes little at night. The temperature of the rice field will not drop too much, and the seedlings will not freeze.

Homework and preview

Homework: After class 3.4.5.6

Preview: Energy conversion when a heat engine works.

How many strokes does a gasoline engine have?

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"Studying the Specific Heat Capacity of Substances" Internal Energy and Heat Engine PPT Courseware 2:

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"Studying the Specific Heat Capacity of Substances" Internal Energy and Heat Engine PPT Courseware:

"Studying the Specific Heat Capacity of Substances" Internal Energy and Heat Engine PPT Courseware Learning Objectives 1. Understand the concept of specific heat capacity, know that specific heat capacity is a characteristic of a substance, a physical quantity that reflects the heat absorption and release properties of a substance, know that the unit of specific heat capacity is J/(kg.℃) and that the specific heat capacity unit...

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Update Time: 2024-08-16

This template belongs to Physics courseware Guangdong and Shanghai Edition Ninth Grade Physics Volume 1 industry PPT template

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