Saturated and unsaturated steam, vapor concentration Lesson plan

Long-term plan section:

Liquid and solid bodies

School:

Teacher’s Name:

Class:

Date

Number of attendees:

Absentees:

10

Lesson topic

Saturated and unsaturated steam, air humidity.

Learning objectives

To determine the relative humidity of the air using a hygrometer and psychrometer

Evaluation Criteria

Students:

- explain the concept of saturated and unsaturated steam, boiling, air humidity, dew point;

- experimentally determine the dependence of pressure, saturated steam on temperature;

- form the skills of the technique of experimental determination of air humidity using a psychrometer and hygrometer.

Language goals

Vocabulary and terminology specific to the subject:

dew point, air humidity, boiling, saturated and unsaturated steam, triple point, psychrometer, hygrometer.

Useful expressions for conversations and writing:

If the temperature of the gas is higher than the critical, then the gas ...

If the temperature of the gas is equal to the critical, then the gas is ...

If the gas temperature is less than the critical, then ...

The greater the external pressure, the higher ...

The boiling point can be lowered if ...

Instilling values

Expanding the outlook of students, the development of functional literacy, responsibility and autonomy in their training.

ICT skills

Work with paper resources, Power Point presentation random wheel:

https://castlots.org/razdelit-na-gruppy/ https://www.jamestease.co.uk/team-generator/

Preliminary knowledge

Molecular structure of substances (air), boiling, evaporation, moisture breath.

Lesson Proper

Planned Lesson Stages

Planned Lesson Activities

Resources

Beginning

2 min

5 min

Your teacher and students greet you via the hand/fingers:

• I wish (they touch my thumbs);
• success (index);
• large (medium);
• in all (nameless);
• and everywhere (little fingers);
• Hello! (touching the whole palm)

Next, students in pairs do the same action.

Thus, the classroom creates a favorable atmosphere for further collaboration.

Slide 1

Actualization of knowledge, challenge:

The teacher proposes to consider the figure on the slide:

“What natural phenomena have you seen now? (Fog, dew, frost).

What do you think, what physical processes are “hidden” in these natural phenomena?

(evaporation, condensation, vaporization, air humidity: fog is a collection of small droplets of water). "

Next, the teacher offers to answer the following questions on the slide:

-        Why is cold and heat so hard carried in our city?

-        Why is the heat in our city so hard to tolerate even 25 ° C, although in other places even a high temperature is more easily tolerated?

-        “Why do patterns appear on windows in winter?”

-        Why if the hot tea is blowing, then it cools faster?

-        Why are sick people so attentive to the weather forecast when air humidity is transmitted?

Afterwards, the teacher leads students to the need to learn a new topic. The topic of the lesson, learning objectives and evaluation criteria are displayed on the screen.

Slides 2-6

Middle

5 min

20 min

The teacher conducts multimedia demonstrations: the features of saturated vapors, the transition of unsaturated steam to the saturation state with a decrease in volume. Based on this, conclusions are drawn.

Students independently formulate conclusions, the teacher checks the students' findings through reading and the class writes them in a notebook.

Conclusions of students and writing in notebooks:

1)      The vapor, which is in thermodynamic equilibrium with its liquid, is called saturated.

2)      The vapor pressure at which a liquid is in equilibrium with its vapor is called the saturated vapor pressure.

3)      The pressure of saturated steam depends only on its chemical composition and temperature and does not depend on the amount of volume it occupies.

4)      With increasing temperature, not only the speed of molecules increases, but also their concentration.

Slides 7-8

Slide 9

The teacher considers individual marginal cases and draws conclusions with the students.

Conclusions of students and writing in notebooks:

1)      If the gas temperature is higher than the critical one, then the gas will not become liquid at any pressure;

2)      If the gas temperature is equal to the critical one, then the gas will become liquid without going to the saturation state;

3)      If the gas temperature is less than the critical, then isothermal compression will cause the gas at the beginning to saturation, and then to the liquid state.

Further on the presentation, the teacher considers the process of boiling, boiling under reduced pressure.

Conclusions of students and writing in notebooks:

1)      Boiling begins at a temperature at which the pressure of saturated steam in the bubbles is compared with the pressure in the liquid;

2)      The greater the external pressure, the higher the boiling point;

3)      The boiling point can be reduced by reducing the external pressure.

The next step, the teacher considers the humidity of the air, the dew point. Teacher: “There is always some amount of water vapor in the air. If there is a lot of water vapor, we say that the air is humid, if it is small it is dry. But how to define this "a lot" or "a little"? Let's solve two problems and compare the results.”

Terms of tasks.

What is the largest amount of water vapor that can be contained in 1 m3 of air at a temperature of 20 °C? 5^oC? When comparing the results, the concepts of absolute and relative humidity, dew point are derived.

Conclusions of students and writing in notebooks:

1)      The pressure that water vapor would produce if all other gases were absent is called the partial pressure of water vapor;

2)      The content of water vapor in 1 m3 of air is called absolute humidity;

3)      The relative humidity of air is the ratio of the partial pressure of water vapor contained in air to the pressure of saturated water vapor at the same temperature;

4)      The temperature at which the water vapor becomes saturated is called the dew point.

Afterwards, the teacher introduces students to instruments for determining the relative humidity of the air.

Slides

10-11

Slides

12-13

Slide 14

Slide 15

Slide 16

5 min

The teacher invites students to work out practical skills; for this, students do laboratory work “Determination of relative humidity of air” and define a “comfort zone” for a physics classroom.

After completing the laboratory work, the teacher offers to solve problems for students. The first task is solved jointly, the second - independently in notebooks.

Task 1. Find the relative humidity of the air if the partial pressure of water vapor in the air at 19 °C was 1.1 kPa.

Task 2. Find the relative humidity of the air in the room at a temperature of 18 °C if dew appeared at a temperature of 10 °C.

Slides

17-18

End

3 min

Homework

Reflection. Evaluation criteria (discuss learning objectives).

The teacher asks questions to the class:

“What caused you difficulty? What is difficult for us to perceive? ”

Discussion of difficulties.

The students are provided with health and safety rules as well as instructions for the next lesson’s lab work to study in advance

Differentiation - how do you plan to provide more support? What tasks do you plan to set for more capable students?

Grading - How do you plan to check students' level of learning?

Health & Safety

I plan to provide support through a general discussion of the results of work with test tasks at the beginning of the lesson, individual counseling during problem solving.

According to the results of the training tasks at the end of each lesson.

Creating a favorable psychological atmosphere, the compliance of tasks to the level of preparedness of students, the change of activities, counseling

Lesson reflection

Were the objectives of the lesson / learning objectives realistic?

Have all students reached the DH?

If not, why not?

Is the differentiation correct in the lesson?

Have the lesson temporal stages been sustained?

What were the deviations from the lesson plan and why?

Use this section to reflect on the lesson. Answer the most important questions about your lesson from the left column.

Overall rating good

What two aspects of the lesson went well (think about both teaching and learning)?

1:

2:

What could contribute to improving the lesson (think about both teaching and learning)?

1:

2:

What did I find out during the lesson about the class or the achievements / difficulties of individual students, what should I look for in subsequent lessons?