Saturated vapor pressure at temperature 15. Saturated vapor pressure at different temperatures. Bath and pressure

« Physics - Grade 10 "

When solving problems, it must be borne in mind that the pressure and density of saturated vapor do not depend on its volume, but depend only on temperature. The ideal gas equation of state is also approximately applicable to the description of saturated steam. But when saturated steam is compressed or heated, its mass does not remain constant.

Some applications may require saturation vapor pressures at certain temperatures. These data must be taken from the table.

Task 1.

A closed vessel with a volume V 1 = 0.5 m 3 contains water weighing m = 0.5 kg. The vessel was heated to a temperature t = 147 °C. By how much should the volume of the vessel be changed so that it contains only saturated steam? Saturated steam pressure p. p at a temperature of t = 147 ° C is equal to 4.7 10 5 Pa.

Decision.

Saturated steam at a pressure of pH. n occupies a volume equal to where M \u003d 0.018 kg / mol is the molar mass of water. The volume of the vessel is V 1 > V, which means that the steam is not saturated. In order for the steam to become saturated, the volume of the vessel must be reduced by

Task 2.

The relative humidity of air in a closed vessel at a temperature of t 1 = 5 ° C is equal to φ 1 = 84%, and at a temperature of t 2 = 22 ° C is equal to φ 2 = 30%. How many times is the saturated vapor pressure of water at temperature t 2 greater than at temperature t 1 ?

Decision.

The water vapor pressure in the vessel at T 1 \u003d 278 K is where r n. n1 - pressure of saturated steam at temperature T 1 . At a temperature T 2 \u003d 295 K, the pressure

Since the volume is constant, according to Charles's law

From here

Task 3.

In a room with a volume of 40 m 3, the air temperature is 20 ° C, its relative humidity φ 1 \u003d 20%. How much water must be evaporated so that the relative humidity φ 2 reaches 50%? It is known that at 20 °C the pressure of saturating vapors is рнп = 2330 Pa.

Decision.

Relative Humidity from here

Steam pressure at relative humidity φ 1 and φ 2

Density is related to pressure by the equation ρ = Mp/RT, whence

Masses of water in the room at humidity φ 1 and φ 2

Mass of water to be evaporated:

Task 4.

In a room with closed windows at a temperature of 15 °C relative humidity φ = 10%. What will be the relative humidity if the temperature in the room rises by 10°C? Saturated vapor pressure at 15 °C p.m. n1 = 12.8 mm Hg. Art., and at 25 ° C p n p2 \u003d 23.8 mm Hg. Art.

Since the steam is unsaturated, the partial pressure of the vapor changes according to Charles's law p 1 /T 1 = p 2 /T 2. From this equation, you can determine the pressure of unsaturated vapor p 2 at T 2: p 2 \u003d p 1 T 2 /T 1. Relative humidity at T 1 is equal.

Arterial hypertension (chronically high blood pressure) is diagnosed with a systolic (lower) index of 140 and above, and a diastolic value of 90. Pathology requires competent therapy and lifestyle changes.

The last point has many restrictions for hypertensive patients. Patients are recommended a health-improving diet, avoiding the use of table salt and alcohol, etc. Accordingly, many are wondering if a bath is allowed for hypertension, is it possible to visit a sauna?

There are many conflicting statements on the Internet related to the fact that visiting the Russian bath and steam room is a way to treat almost all diseases, including hypertension. But is it really so?

So, how can wet and dry steam affect the state of hypertension, will the pressure rise or fall? In what situations is a visit useful, and when is it forbidden?

Bath and pressure

As already noted, there are many opinions about the compatibility of high pressure, for example, 150-152 / 100-110, and baths. Despite all the statements of adherents of non-traditional treatment about the benefits of a bath with high blood pressure, the issue is controversial.

Under the influence of wet steam and high temperature conditions, the human heart begins to contract more actively, which will lead to an increase in arterial parameters. The output is a vicious circle.

Intense contractility provokes a rush of blood into the arteries and blood vessels, they expand rapidly, but the volume of circulating fluid is the same, respectively, the heart needs to contract more often.

If such a process in a healthy person does not cause a pathological condition, then with hypertension the picture is reversed. His blood pressure is 140/90 (grade 1 disease) can jump up to 160/130, resulting in a hypertensive crisis.

In people suffering from hypertension, there is an increased contraction of the heart muscle. Increased blood circulation will negatively affect the functioning of the cardiovascular system.

Metabolic processes are disturbed, the pulse rate increases to 160-170 beats per minute. This makes the heart work hard. Moreover, the load is maintained even after leaving the bath.

A Russian bath without a steam room is nonsense. However, it is strictly prohibited for hypertension.

If, against the background of degrees 1 and 2, an exception can be made, the doctor will allow going to the bath complex, then at stages 3 and 4, a pleasant pastime equals death.

The effect of bath procedures on blood pressure

Does bathing raise or lower blood pressure? Hypertensive patients want to live a full life, despite their illness, but many moments with a diagnosis remain in the past.

The steam room has a lot of advantages. While in a hot room, the process of removing toxic substances from the body is accelerated due to increased sweating. The heart rate increases, blood pressure decreases; there is a feeling of relaxation and relaxation. But all these points are applicable only to a healthy person.

In a bath in healthy individuals, the pressure will begin to decrease, however, after leaving a warm room, it will normalize within 10-15 minutes to the required values.

Hypertensive patients in the steam room can “observe” a slight decrease in blood pressure or a sharp drop in it. In other words, it is impossible to predict how the body will react to the procedure.

With a sharp jump in SD and DD, symptoms join:

• Headache.
• Nausea.
• Strong weakness.

Ignoring the situation can lead to loss of consciousness and subsequent fall, fraught with injury.

At stages 3 and 4 of a chronic disease, a steam room and a bath significantly increase the risk of complications. And those who have a history of heart attack or stroke are strictly prohibited.

Bath, sauna and stages of hypertension

Numerous studies have proven that the loads received by a hypertensive person in a sauna are a more gentle option, unlike a bath. At a pressure of 140/100 mmHg, a trip to the sauna is acceptable, the pulse increases to 110 beats per minute.

In the sauna, the cardiovascular system experiences less stress, the vessels dilate gradually, which makes it possible to exclude metabolic disorders in the myocardium, respectively, they quickly return to normal.

After analyzing numerous information, we can conclude that with 1 and 2 degrees of GB at a pressure of 140/80 and slightly higher, it is possible to visit “hot” places. In some cases, this will bring disproportionate benefits when joint and muscle pain is pestering.

In this case, patients should take into account the systematic increase in blood pressure, indicators before the procedure, the pulse rate. With relatively low values, you can bathe, drink herbal tea, apply hypertonic dressings.

Going to the bath can be an effective way to improve well-being and the condition of blood vessels.

Danger for hypertensive patients

As already noted, SD and DD can decrease or increase in the bath. Therefore, before going to such an institution, the patient is advised to weigh all the pros and cons.

Stably high blood pressure provokes a violation of blood vessels that feed the heart, brain, organs of visual perception. They are the first to "feel" the negative impact of the disease, which leads to atherosclerotic changes, blindness, heart attacks and strokes.

At stages 1 and 2 of hypertension, there is no damage to target organs, so it is possible to visit the bathhouse without negative consequences. At 3 and 4 degrees - the risk of complications increases several times.

It is under the influence of hot air that internal organs experience an enormous load, and “collapse” occurs in weak areas. Moreover, changes occur so quickly that the patient does not have time to understand what is happening. It can simply fall due to a malfunction in the body.

When a hypertensive patient's blood pressure has increased to 145/130 or higher, nosebleeds are detected, then you need to "rejoice" that the blood flows out, and not into the brain, which is fraught with disability and death.

Therefore, the decision to visit the sauna, bath and steam room is made by everyone individually, taking into account all the risks.

What should be considered when going to the bath?

Why it is not recommended to visit such institutions, it was found out. Now consider a list of tips that will help reduce the risk of complications when visiting them. First of all, you should consult a doctor. If GB is complicated by VVD, then the trip is strictly prohibited.

The head is a "weak" place that needs protection. It is necessary to wear a felt hat designed for steam manipulation.

Elementary rules:

1. Hypertensive patients are not recommended to go to the institution on their own, only with an escort. This is in case the patient loses consciousness and falls.
2. A sharp change in temperature is strictly prohibited. For example, a steam room - a cold pool - a hot shower, etc. Changes will provoke a rapid heartbeat, the load on the heart will increase, and pain in the sternum will appear. The pressure may rise.
3. It is recommended to go on an empty stomach, or eat, but not enough. Do not drink alcohol or energy drinks.

The pressure after the bath is able to rise, the pulse will quicken. Therefore, after it you need to rest for about an hour, do not burden the body. This is necessary in order for all processes to come to a normal state.

Thus, bathing procedures affect blood pressure in different ways, it can rise, or it can fall sharply. It is impossible to predict how the body will react in a given situation.

Bath drinks

We repeat that alcohol should not be consumed by hypertensive patients at all, and especially in the bath. Some believe that it helps lower blood pressure. However, this effect is short-term, then a sharp jump is observed.

The ideal option is various herbal teas. Peppermint tea relaxes and soothes when the cause of hypertension is psychological stress. Fall asleep in a thermos 3 tbsp. spoons of raw materials, pour boiling water. Steam for 2 hours.

A good collection for a bath that helps lower blood pressure without pills. It consists of calendula inflorescences, periwinkle roots, mint leaves. Forty grams of the mixture is poured into 500 ml of boiling water, insisted. At one time, drink 50 ml.

In case of hypertension, a collection of rose hips, rowan fruits, hawthorn is effective: for 500 ml of water, 100 grams of raw materials, insist for an hour. Drink like tea.

The best modern remedy for hypertension and high blood pressure. 100% pressure control guarantee and excellent prevention!

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Table 3

Calculation formulas for the pH of buffer solutions and solutions of hydrolyzable salts

Designations in formulas:

K – dissociation constants: Kc – acids, Co– bases; K2k - acids in 2 stages.

рКк = - lgКк; pKo = - lgKo; рК2к = - lgК2к;

С – molar concentrations: Ск – acids; Co - bases;

CH2PO4 - and CHPO4 2- - corresponding ions.

Table 4

Dissociation constant of weak acids and bases

Table 5

Instability constants of some complex ions

Table 6

Table of decimal logarithms

Note. The table allows you to determine the approximate values ​​of the logarithms up to the second decimal place. For more accurate calculations, use Bradis tables.

How to find the logarithm of a number?

1. If the number is in the range from 1 to 10, its logarithm is found in the table.

Example: the value lg5,50 is at the intersection of the horizontal "5" and the vertical ".50"; lg5.50 = 0.74;

The value lg5.05 is at the intersection of the vertical "5" and the horizontal ".05" lg5.05 ≈ 0.70.

2. If the number is not included in the specified interval, it is represented as two factors, one of which lies in the specified interval from 1 to 10:

Example: the value lg0.55 is found like this:

lg0.55 = lg5.5*10 -1 = lg5.5 + lg10 -1 = 0.74 + (-1) = -0.26.

How to find a number by its logarithm?

1. If the logarithm is a positive number, it is represented as the sum of the integer and fractional parts, and is found in the table.

For example: lg x \u003d 2.618 \u003d 2 + 0.618. A number whose logarithm is 2 is 10 2.

x \u003d 4.15 * 10 2 \u003d 415.

2. If the logarithm of the number is negative, for example lg x = -2.372.

Then we represent the value - 2.372 as the sum of a negative integer and a positive fraction: -2.372 \u003d -3 + 0.618 (add -3 + 0.618).

Standard electrode potentials E° in aqueous solutions at 25°C

LITERATURE

1. Knyazev D.A. Inorganic chemistry / D.A. Knyazev, S.N. Smarygin. - M.: Higher school, 1990. - 430 p.

2. Lidin R.A. Handbook of inorganic chemistry / R.A. Lidin, L.L. Andreeva, V.A. Milk. – M.: Chemistry, 1987. – 480 p.

3. Guidelines for the implementation of tests in chemistry /A.V. Bogachev, G.K. Stepanova, N.A. Fedorova, V.I. Pichushkin. - Yaroslavl, YAFTSHA, 1986. - 82 p.

4. Guidelines for the task for students' independent work at the course of inorganic chemistry / B.A. Rybakova, L.S. Krysina, Z.E. Deikova and others - M .: TSHA, 1987. - 36 p.

5. Guidelines for laboratory work in general chemistry /Yu.A. Goryunov, L.V. Velikanova, A.V. Bogachev, G.K. Stepanova. -Yaroslavl, YASHI, 1994. - 44 p.