The volume of a substance under normal conditions. Volume of one mole of gas under normal conditions

The mass of 1 mole of a substance is called molar. What is the volume of 1 mole of a substance called? Obviously, this is also called molar volume.

What is the molar volume of water? When we measured 1 mole of water, we did not weigh 18 g of water on the scales - this is inconvenient. We used measuring utensils: a cylinder or a beaker, since we knew that the density of water is 1 g/ml. Therefore, the molar volume of water is 18 ml/mol. For liquids and solids, the molar volume depends on their density (Fig. 52, a). It's a different matter for gases (Fig. 52, b).

Rice. 52.
Molar volumes (n.s.):
a - liquids and solids; b - gaseous substances

If you take 1 mol of hydrogen H 2 (2 g), 1 mol of oxygen O 2 (32 g), 1 mol of ozone O 3 (48 g), 1 mol carbon dioxide CO 2 (44 g) and even 1 mole of water vapor H 2 O (18 g) under the same conditions, for example normal (in chemistry it is usually called normal conditions (n.s.) temperature 0 ° C and pressure 760 mm Hg. Art. , or 101.3 kPa), then it turns out that 1 mole of any of the gases will occupy the same volume, equal to 22.4 liters, and contain the same number of molecules - 6 × 10 23.

And if you take 44.8 liters of gas, then how much of its substance will be taken? Of course, 2 moles, since the given volume is twice the molar volume. Hence:

where V is the volume of gas. From here

Molar volume is physical quantity, equal to the ratio of the volume of a substance to the amount of a substance.

The molar volume of gaseous substances is expressed in l/mol. Vm - 22.4 l/mol. The volume of one kilomole is called kilomolar and is measured in m 3 /kmol (Vm = 22.4 m 3 /kmol). Accordingly, the millimolar volume is 22.4 ml/mmol.

Problem 1. Find the mass of 33.6 m 3 of ammonia NH 3 (n.s.).

Problem 2. Find the mass and volume (n.v.) of 18 × 10 20 molecules of hydrogen sulfide H 2 S.

When solving the problem, let's pay attention to the number of molecules 18 × 10 20. Since 10 20 is 1000 times less than 10 23, obviously, calculations should be carried out using mmol, ml/mmol and mg/mmol.

Key words and phrases

  1. Molar, millimolar and kilomolar volumes of gases.
  2. Molar volume of gases (at normal conditions) is equal to 22.4 l/mol.
  3. Normal conditions.

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Questions and tasks

  1. Find the mass and number of molecules at n. u. for: a) 11.2 l of oxygen; b) 5.6 m 3 nitrogen; c) 22.4 ml of chlorine.
  2. Find the volume that at n. u. will take: a) 3 g of hydrogen; b) 96 kg of ozone; c) 12 × 10 20 nitrogen molecules.
  3. Find the densities (mass 1 liter) of argon, chlorine, oxygen and ozone at room temperature. u. How many molecules of each substance will be contained in 1 liter under the same conditions?
  4. Calculate the mass of 5 liters (n.s.): a) oxygen; b) ozone; c) carbon dioxide CO 2.
  5. Indicate which is heavier: a) 5 liters of sulfur dioxide (SO 2) or 5 liters of carbon dioxide (CO 2); b) 2 l of carbon dioxide (CO 2) or 3 l carbon monoxide(SO).

The volume of gas can be determined using several formulas. It is necessary to choose the appropriate one based on the data in the condition of the quantities problem. A major role in selecting the desired formula is played by these media, and in particular: pressure and temperature.

Instructions

1. The formula that is especially often encountered in problems is: V = n*Vm, where V is the volume of gas (l), n is the number of substance (mol), Vm is the molar volume of gas (l/mol), under typical conditions (n.s.) is a standard value and is equal to 22.4 l/mol. It happens that the condition does not contain the number of a substance, but there is a mass of a certain substance, then we do this: n = m/M, where m is the mass of the substance (g), M is the molar mass of the substance (g/mol). We find the molar mass using the table D.I. Mendeleev: under each element its nuclear mass is written, we add up all the masses and get the one we need. But such problems are quite rare; usually the problem contains a reaction equation. The solution to such problems changes a little. Let's look at an example.

2. What volume of hydrogen will be released under typical conditions if aluminum weighing 10.8 g is dissolved in excess hydrochloric acid. We write the reaction equation: 2Al + 6HCl(ex.) = 2AlCl3 + 3H2. Solve the problem about this equation. Find the number of aluminum substances that reacted: n(Al) = m(Al)/M(Al). In order to substitute the data into this formula, we need to calculate the molar mass of aluminum: M(Al) = 27 g/mol. We substitute: n(Al) = 10.8/27 = 0.4 mol. From the equation we see that when 2 moles of aluminum are dissolved, 3 moles of hydrogen are formed. We calculate what amount of hydrogen substance is formed from 0.4 mol of aluminum: n(H2) = 3 * 0.4/2 = 0.6 mol. After this, we substitute the data into the formula for finding the volume of hydrogen: V = n*Vm = 0.6*22.4 = 13.44 liters. So we got the result.

3. If we are dealing with a gas system, then the following formula holds: q(x) = V(x)/V, where q(x)(phi) is the volume fraction of the component, V(x) is the volume of the component (l), V – system volume (l). To find the volume of a component, we obtain the formula: V(x) = q(x)*V. And if you need to find the volume of the system, then: V = V(x)/q(x).

A gas in which the interaction between molecules is negligible is considered impeccable. In addition to pressure, the state of a gas is characterized by temperature and volume. The relationships between these parameters are reflected in the gas laws.

Instructions

1. The pressure of a gas is directly proportional to its temperature, the amount of substance, and inversely proportional to the volume of the container occupied by the gas. The proportionality indicator is the universal gas continuous R, approximately equal to 8.314. It is measured in joules divided by moles and kelvins.

2. This arrangement forms the mathematical connection P=?RT/V, where? – number of substance (mol), R=8.314 – universal gas continuous (J/mol K), T – gas temperature, V – volume. Pressure is expressed in pascals. It can also be expressed in atmospheres, with 1 atm = 101.325 kPa.

3. The considered connectivity is a consequence of the Mendeleev-Clapeyron equation PV=(m/M) RT. Here m is the mass of the gas (g), M is its molar mass (g/mol), and the fraction m/M results in the number of substance?, or the number of moles. The Mendeleev-Clapeyron equation is objective for all gases that can be considered impeccable. This is a fundamental physical and chemical gas law.

4. When monitoring the behavior of an ideal gas, we talk about so-called typical conditions - conditions environment, which we especially often have to deal with in reality. Thus, typical data (n.s.) assume a temperature of 0 degrees Celsius (or 273.15 degrees on the Kelvin scale) and a pressure of 101.325 kPa (1 atm). A value has been discovered that equals the volume of one mole of an ideal gas under the following conditions: Vm = 22.413 l/mol. This volume is called molar. Molar volume is one of the main chemical constants used in solving problems.

5. The main thing to understand is that with continuous pressure and temperature, the volume of the gas also does not change. This fascinating postulate is formulated in Avogadro's law, which states that the volume of a gas is directly proportional to the number of moles.

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Pay attention!
There are other formulas for finding volume, but if you need to find the volume of a gas, only the formulas given in this article are suitable.

In order to find out the composition of any gaseous substances, you must be able to operate with concepts such as molar volume, molar mass and density of the substance. In this article, we will look at what molar volume is and how to calculate it?

Quantity of substance

Quantitative calculations are carried out in order to actually carry out a particular process or to find out the composition and structure of a certain substance. These calculations are inconvenient to perform with absolute values ​​of the mass of atoms or molecules due to the fact that they are very small. Relative atomic masses also cannot be used in most cases, since they are not related to generally accepted measures of mass or volume of a substance. Therefore, the concept of quantity of a substance was introduced, which is denoted Greek letter v (nude) or n. The amount of a substance is proportional to the number of structural units (molecules, atomic particles) contained in the substance.

The unit of quantity of a substance is the mole.

A mole is an amount of substance that contains the same number of structural units as there are atoms contained in 12 g of a carbon isotope.

The mass of 1 atom is 12 a. e.m., therefore the number of atoms in 12 g of carbon isotope is equal to:

Na= 12g/12*1.66057*10 to the power-24g=6.0221*10 to the power of 23

The physical quantity Na is called Avogadro's constant. One mole of any substance contains 6.02 * 10 to the power of 23 particles.

Rice. 1. Avogadro's law.

Molar volume of gas

The molar volume of a gas is the ratio of the volume of a substance to the amount of that substance. This value is calculated by dividing molar mass substance by its density according to the following formula:

where Vm is the molar volume, M is the molar mass, and p is the density of the substance.

Rice. 2. Molar volume formula.

IN international system The measurement of the molar volume of gaseous substances is carried out in cubic meters per mole (m 3 /mol)

The molar volume of gaseous substances differs from substances in liquid and solid states in that a gaseous element with an amount of 1 mole always occupies the same volume (if the same parameters are met).

The volume of gas depends on temperature and pressure, so when calculating, you should take the volume of gas under normal conditions. Normal conditions are considered to be a temperature of 0 degrees and a pressure of 101.325 kPa. The molar volume of 1 mole of gas under normal conditions is always the same and equal to 22.41 dm 3 /mol. This volume is called molar volume ideal gas. That is, in 1 mole of any gas (oxygen, hydrogen, air) the volume is 22.41 dm 3 /m.

Rice. 3. Molar volume of gas under normal conditions.

Table "molar volume of gases"

The following table shows the volume of some gases:

Gas Molar volume, l
H 2 22,432
O2 22,391
Cl2 22,022
CO2 22,263
NH 3 22,065
SO 2 21,888
Ideal 22,41383

What have we learned?

The molar volume of a gas studied in chemistry (grade 8), along with molar mass and density, are necessary quantities for determining the composition of a particular chemical substance. A feature of a molar gas is that one mole of gas always contains the same volume. This volume is called the molar volume of the gas.

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^ Molar mass and molar volume of a substance. Molar mass is the mass of a mole of a substance. It is calculated through the mass and amount of the substance using the formula:

Мв = К· Мr (1)

Where: K is the proportionality coefficient equal to 1 g/mol.

In fact, for the carbon isotope 12 6 C Ar = 12, and the molar mass of atoms (by the definition of the concept “mole”) is 12 g/mol. Consequently, the numerical values ​​of the two masses coincide, which means K = 1. It follows that the molar mass of a substance, expressed in grams per mole, has the same numerical value as its relative molecular mass(atomic) weight. Thus, the molar mass of atomic hydrogen is 1.008 g/mol, molecular hydrogen – 2.016 g/mol, molecular oxygen – 31.999 g/mol.

According to Avogadro's law, the same number of molecules of any gas occupies the same volume under the same conditions. On the other hand, 1 mole of any substance contains (by definition) the same number of particles. It follows that at a certain temperature and pressure, 1 mole of any substance in the gaseous state occupies the same volume.

The ratio of the volume occupied by a substance to its quantity is called the molar volume of the substance. Under normal conditions (101.325 kPa; 273 K), the molar volume of any gas is equal to 22,4l/mol(more precisely, Vn = 22.4 l/mol). This statement is true for such a gas, when other types of interaction of its molecules with each other, except for their elastic collision, can be neglected. Such gases are called ideal. For non-ideal gases, called real gases, the molar volumes are different and slightly different from exact value. However, in most cases the difference is reflected only in the fourth and subsequent significant figures.

Measurements of gas volumes are usually carried out under conditions other than normal. To bring the volume of gas to normal conditions, you can use an equation combining the gas laws of Boyle - Mariotte and Gay - Lussac:

pV / T = p 0 V 0 / T 0

Where: V is the volume of gas at pressure p and temperature T;

V 0 – volume of gas at normal pressure p 0 (101.325 kPa) and temperature T 0 (273.15 K).

The molar masses of gases can also be calculated using the equation of state of an ideal gas - the Clapeyron - Mendeleev equation:

pV = m B RT / M B ,

Where: p – gas pressure, Pa;

V – its volume, m3;

M B - mass of substance, g;

M B – its molar mass, g/mol;

T - absolute temperature, TO;

R is the universal gas constant equal to 8.314 J / (mol K).

If the volume and pressure of a gas are expressed in other units of measurement, then the value of the gas constant in the Clapeyron–Mendeleev equation will take on a different value. It can be calculated using a formula derived from the combined law gas state for a mole of substance under normal conditions for one mole of gas:

R = (p 0 V 0 / T 0)

Example 1. Express in moles: a) 6.0210 21 CO 2 molecules; b) 1.2010 24 oxygen atoms; c) 2.0010 23 water molecules. What is the molar mass of these substances?

Solution. A mole is the amount of a substance that contains a number of particles of any particular kind equal to Avogadro's constant. Hence, a) 6.0210 21 i.e. 0.01 mol; b) 1.2010 24, i.e. 2 mol; c) 2.0010 23, i.e. 1/3 mol. The mass of a mole of a substance is expressed in kg/mol or g/mol. The molar mass of a substance in grams is numerically equal to its relative molecular (atomic) mass, expressed in atomic mass units (amu)

Since the molecular weights of CO 2 and H 2 O and atomic mass oxygen are respectively equal to 44; 18 and 16 amu, then their molar masses are equal: a) 44 g/mol; b) 18g/mol; c) 16 g/mol.

Example 2. Calculate the absolute mass of a sulfuric acid molecule in grams.

Solution. A mole of any substance (see example 1) contains Avogadro’s constant N A of structural units (in our example, molecules). The molar mass of H 2 SO 4 is 98.0 g/mol. Therefore, the mass of one molecule is 98/(6.02 10 23) = 1.63 10 -22 g.

Molar volume- the volume of one mole of a substance, the value obtained by dividing the molar mass by the density. Characterizes the packing density of molecules.

Meaning N A = 6.022…×10 23 called Avogadro's number after the Italian chemist Amedeo Avogadro. This is the universal constant for tiny particles any substance.

It is this number of molecules that contains 1 mole of oxygen O2, the same number of atoms in 1 mole of iron (Fe), molecules in 1 mole of water H2O, etc.

According to Avogadro's law, 1 mole of an ideal gas at normal conditions has the same volume Vm= 22.413 996(39) l. Under normal conditions, most gases are close to ideal, so all background information on the molar volume of chemical elements refers to their condensed phases, unless otherwise stated

Along with mass and volume in chemical calculations Often, an amount of substance is used that is proportional to the number of structural units contained in the substance. In each case, it must be indicated which structural units (molecules, atoms, ions, etc.) are meant. The unit of quantity of a substance is the mole.

Mole is the amount of substance containing as many molecules, atoms, ions, electrons or other structural units as there are atoms in 12 g of the 12C carbon isotope.

The number of structural units contained in 1 mole of a substance (Avogadro's constant) is determined with great accuracy; in practical calculations it is taken equal to 6.02 1024 mol -1.

It is not difficult to show that the mass of 1 mole of a substance (molar mass), expressed in grams, is numerically equal to the relative molecular mass of this substance.

Yes, relative molecular weight(or, abbreviated molecular weight) of free chlorine C1g is 70.90. Therefore, the molar mass of molecular chlorine is 70.90 g/mol. However, the molar mass of chlorine atoms is half as much (45.45 g/mol), since 1 mole of Cl chlorine molecules contains 2 moles of chlorine atoms.

According to Avogadro's law, equal volumes Any gas taken at the same temperature and the same pressure contains the same number of molecules. In other words, the same number of molecules of any gas occupies the same volume under the same conditions. At the same time, 1 mole of any gas contains the same number of molecules. Consequently, under the same conditions, 1 mole of any gas occupies the same volume. This volume is called the molar volume of the gas and under normal conditions (0°C, pressure 101, 425 kPa) is equal to 22.4 liters.

For example, the statement “the carbon dioxide content of the air is 0.04% (vol.)” means that at a partial pressure of CO 2 equal to the air pressure and at the same temperature, the carbon dioxide contained in the air will take up 0.04% of the total volume occupied by air.

Test task

1. Compare the number of molecules contained in 1 g of NH 4 and in 1 g of N 2. In which case and how many times is the number of molecules greater?

2. Express the mass of one sulfur dioxide molecule in grams.



4. How many molecules are there in 5.00 ml of chlorine under normal conditions?

4. What volume under normal conditions is occupied by 27 10 21 gas molecules?

5. Express the mass of one NO 2 molecule in grams -

6. What is the ratio of the volumes occupied by 1 mole of O2 and 1 mole of Oz (the conditions are the same)?

7. Equal masses of oxygen, hydrogen and methane are taken under the same conditions. Find the ratio of the volumes of gases taken.

8. To the question of how much volume 1 mole of water will occupy under normal conditions, the answer was: 22.4 liters. Is this the correct answer?

9. Express the mass of one HCl molecule in grams.

How many molecules of carbon dioxide are there in 1 liter of air if the volumetric content of CO 2 is 0.04% (normal conditions)?

10. How many moles are contained in 1 m 4 of any gas under normal conditions?

11. Express in grams the mass of one molecule of H 2 O-

12. How many moles of oxygen are in 1 liter of air, if the volume

14. How many moles of nitrogen are in 1 liter of air if its volumetric content is 78% (normal conditions)?

14. Equal masses of oxygen, hydrogen and nitrogen are taken under the same conditions. Find the ratio of the volumes of gases taken.

15. Compare the number of molecules contained in 1 g of NO 2 and in 1 g of N 2. In which case and how many times is the number of molecules greater?

16. How many molecules are contained in 2.00 ml of hydrogen under standard conditions?

17. Express in grams the mass of one molecule of H 2 O-

18. What volume under normal conditions is occupied by 17 10 21 gas molecules?

RATE OF CHEMICAL REACTIONS

When defining the concept speed chemical reaction it is necessary to distinguish between homogeneous and heterogeneous reactions. If a reaction occurs in a homogeneous system, for example, in a solution or in a mixture of gases, then it occurs throughout the entire volume of the system. Speed ​​of homogeneous reaction is the amount of a substance that reacts or is formed as a result of a reaction per unit time per unit volume of the system. Since the ratio of the number of moles of a substance to the volume in which it is distributed is the molar concentration of the substance, the rate of a homogeneous reaction can also be defined as change in concentration per unit time of any of the substances: the initial reagent or the reaction product. To ensure that the calculation result is always positive, regardless of whether it is based on a reagent or a product, the “±” sign is used in the formula:



Depending on the nature of the reaction, time can be expressed not only in seconds, as required by the SI system, but also in minutes or hours. During the reaction, the magnitude of its speed is not constant, but continuously changes: it decreases, as the concentrations of the starting substances decrease. The above calculation gives the average value of the reaction rate over a certain time interval Δτ = τ 2 – τ 1. True (instantaneous) speed is defined as the limit to which the ratio Δ tends WITH/ Δτ at Δτ → 0, i.e., the true speed is equal to the derivative of the concentration with respect to time.

For a reaction in the equation of which there are stoichiometric coefficients that differ from unity, the rate values ​​expressed for different substances are not the same. For example, for the reaction A + 4B = D + 2E, the consumption of substance A is one mole, that of substance B is three moles, and the supply of substance E is two moles. That's why υ (A) = ⅓ υ (B) = υ (D) =½ υ (E) or υ (E) . = ⅔ υ (IN) .

If a reaction occurs between substances located in different phases of a heterogeneous system, then it can only occur at the interface between these phases. For example, the interaction between an acid solution and a piece of metal occurs only on the surface of the metal. Speed ​​of heterogeneous reaction is the amount of a substance that reacts or is formed as a result of a reaction per unit time per unit interface surface:

.

The dependence of the rate of a chemical reaction on the concentration of reactants is expressed by the law active masses: at a constant temperature, the rate of a chemical reaction is directly proportional to the product of the molar concentrations of the reacting substances raised to powers equal to the coefficients in the formulas of these substances in the reaction equation. Then for the reaction

2A + B → products

the ratio is valid υ ~ · WITH A 2 · WITH B, and to transition to equality a proportionality coefficient is introduced k, called reaction rate constant:

υ = k· WITH A 2 · WITH B = k·[A] 2 ·[B]

(molar concentrations in formulas can be denoted by the letter WITH with the corresponding index and the formula of the substance enclosed in square brackets). The physical meaning of the reaction rate constant is the reaction rate at concentrations of all reactants equal to 1 mol/l. The dimension of the reaction rate constant depends on the number of factors on the right side of the equation and can be c –1 ; s –1 ·(l/mol); s –1 · (l 2 /mol 2), etc., that is, such that in any case, in calculations, the reaction rate is expressed in mol · l –1 · s –1.

For heterogeneous reactions, the equation of the law of mass action includes the concentrations of only those substances that are in the gas phase or in solution. The concentration of a substance in the solid phase is a constant value and is included in the rate constant, for example, for the combustion process of coal C + O 2 = CO 2, the law of mass action is written:

υ = kI·const··= k·,

Where k= kI const.

In systems where one or more substances are gases, the rate of reaction also depends on pressure. For example, when hydrogen interacts with iodine vapor H 2 + I 2 = 2HI, the rate of the chemical reaction will be determined by the expression:

υ = k··.

If you increase the pressure, for example, by 4 times, then the volume occupied by the system will decrease by the same amount, and, consequently, the concentrations of each of the reacting substances will increase by the same amount. The reaction rate in this case will increase 9 times

Dependence of reaction rate on temperature described by van't Hoff's rule: with every 10 degree increase in temperature, the reaction rate increases by 2-4 times. This means that as the temperature rises in arithmetic progression the rate of a chemical reaction increases exponentially. The base in the progression formula is temperature coefficient of reaction rateγ, showing how many times the rate of a given reaction increases (or, which is the same thing, the rate constant) with an increase in temperature by 10 degrees. Mathematically, Van't Hoff's rule is expressed by the formulas:

or

where and are the reaction rates, respectively, at the initial t 1 and final t 2 temperatures. Van't Hoff's rule can also be expressed by the following relations:

; ; ; ,

where and are, respectively, the rate and rate constant of the reaction at temperature t; and – the same values ​​at temperature t +10n; n– number of “ten-degree” intervals ( n =(t 2 –t 1)/10), by which the temperature has changed (can be an integer or fractional number, positive or negative).

Test task

1. Find the value of the rate constant for the reaction A + B -> AB, if at concentrations of substances A and B equal to 0.05 and 0.01 mol/l, respectively, the reaction rate is 5 10 -5 mol/(l-min).

2. How many times will the rate of reaction 2A + B -> A2B change if the concentration of substance A is increased by 2 times, and the concentration of substance B is decreased by 2 times?

4. How many times should the concentration of the substance, B 2 in the system 2A 2 (g) + B 2 (g) = 2A 2 B (g), be increased so that when the concentration of substance A decreases by 4 times, the rate of the direct reaction does not change ?

4. Some time after the start of the reaction 3A+B->2C+D, the concentrations of substances were: [A] =0.04 mol/l; [B] = 0.01 mol/l; [C] =0.008 mol/l. What are the initial concentrations of substances A and B?

5. In the system CO + C1 2 = COC1 2, the concentration was increased from 0.04 to 0.12 mol/l, and the chlorine concentration was increased from 0.02 to 0.06 mol/l. How many times did the rate of the forward reaction increase?

6. The reaction between substances A and B is expressed by the equation: A + 2B → C. The initial concentrations are: [A] 0 = 0.04 mol/l, [B] o = 0.05 mol/l. The reaction rate constant is 0.4. Find initial speed reactions and the reaction rate after some time, when the concentration of substance A decreases by 0.01 mol/l.

7. How will the rate of the reaction 2CO + O2 = 2CO2, occurring in a closed vessel, change if the pressure is doubled?

8. Calculate how many times the reaction rate will increase if the temperature of the system is increased from 20 °C to 100 °C, taking the value of the temperature coefficient of the reaction rate equal to 4.

9. How will the reaction rate 2NO(r.) + 0 2 (g.) → 2N02(r.) change if the pressure in the system is increased by 4 times;

10. How will the reaction rate 2NO(r.) + 0 2 (g.) → 2N02(r.) change if the volume of the system is reduced by 4 times?

11. How will the rate of the reaction 2NO(r.) + 0 2 (g.) → 2N02(r.) change if the concentration of NO is increased by 4 times?

12. What is the temperature coefficient of the reaction rate if, with an increase in temperature by 40 degrees, the reaction rate

increases by 15.6 times?

14. . Find the value of the rate constant for the reaction A + B -> AB, if at concentrations of substances A and B equal to 0.07 and 0.09 mol/l, respectively, the reaction rate is 2.7 10 -5 mol/(l-min).

14. The reaction between substances A and B is expressed by the equation: A + 2B → C. The initial concentrations are: [A] 0 = 0.01 mol/l, [B] o = 0.04 mol/l. The reaction rate constant is 0.5. Find the initial reaction rate and the reaction rate after some time, when the concentration of substance A decreases by 0.01 mol/l.

15. How will the reaction rate 2NO(r.) + 0 2 (g.) → 2N02(r.) change if the pressure in the system is doubled;

16. In the system CO + C1 2 = COC1 2, the concentration was increased from 0.05 to 0.1 mol/l, and the chlorine concentration was increased from 0.04 to 0.06 mol/l. How many times did the rate of the forward reaction increase?

17. Calculate how many times the reaction rate will increase if the temperature of the system is increased from 20 °C to 80 °C, taking the value of the temperature coefficient of the reaction rate equal to 2.

18. Calculate how many times the reaction rate will increase if the temperature of the system is increased from 40 °C to 90 °C, taking the value of the temperature coefficient of the reaction rate equal to 4.

CHEMICAL BOND. FORMATION AND STRUCTURE OF MOLECULES

1.What types of chemical bonds do you know? Give an example of the formation of an ionic bond using the valence bond method.

2. Which one chemical bond called covalent? What is characteristic of the covalent type of bond?

4. What properties are characterized by a covalent bond? Show this with specific examples.

4. What type of chemical bond is in H2 molecules; Cl 2 HC1?

5.What is the nature of the bonds in molecules? NCI 4 CS 2, CO 2? Indicate for each of them the direction of displacement of the common electron pair.

6. What chemical bond is called ionic? What is characteristic of the ionic type of bond?

7. What type of bond is in the molecules NaCl, N 2, Cl 2?

8. Picture everything possible ways overlap of the s-orbital with the p-orbital;. Indicate the direction of communication in this case.

9. Explain the donor-acceptor mechanism covalent bond using the example of the formation of phosphonium ion [PH 4 ]+.

10. In CO molecules, C0 2, is the bond polar or nonpolar? Explain. Describe hydrogen bonding.

11. Why are some molecules that have polar bonds generally nonpolar?

12.Covalent or ion type communication is typical for following connections: Nal, S0 2, KF? Why ionic bond is the limiting case of covalent?

14. What is metal connection? How is it different from a covalent bond? What properties of metals does it determine?

14. What is the nature of the bonds between atoms in molecules; KHF 2, H 2 0, HNO ?

15. How can we explain the high bond strength between atoms in the nitrogen molecule N2 and the significantly lower strength in the phosphorus molecule P4?

16. What kind of bond is called a hydrogen bond? Why do molecules of H2S and HC1, in contrast to H2O and HF, form hydrogen bonds not typical?

17. What bond is called ionic? Does an ionic bond have the properties of saturation and directionality? Why is it an extreme case of covalent bonding?

18. What type of bond is in the NaCl, N 2, Cl 2 molecules?



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