Mol - Bài 18 - Hóa học 8 - Cô Nguyễn Thị Thu (HAY NHẤT)

Hello, I'm Ms. Thu, a member of the website Oc.vzach.com Today, we will join together in the 8th science show and we will go to the 18th topic, which is MOL MOL is one of the important data in the general science show and we have to understand the value of MOL as well as the mathematical formulas related to MOL in order to be able to solve the equations related to chemistry In this show, we will learn about some main topics In the first topic, we will answer the question, what is MOL? After that, we will define the mole fraction and finally, the mole fraction of the gas Let's go to the first part, what is MOL? MOL is the amount of gas containing 6 into 10 to the power of 3 or the mole fraction of that gas So, what is the value of 6 into 10 to the power of 3? The value of 6 into 10 to the power of 3 is the number Avogadro and the symbol is the letter N Why is it here? Sometimes it is the mole fraction, sometimes it is the mole fraction It corresponds to the gas we are dealing with For example, if you have one atom of atom A then we will see that the amount of gas in one atom of atom A is 6 into 10 to the power of 23 atom A and when we are dealing with an atom its ratio is 6 into 10 to the power of 23 atom Specifically, you have the number Avogadro which is the symbol is the letter N which is 6 into 10 to the power of 23 and there are some examples like this For example, one atom of atom A here we have the number atom it will be 6 into 10 to the power of 23 atom A corresponding to one atom of water it will be 6 into 10 to the power of 23 water atom So, if the gas we are dealing with is the atom then the value corresponding to the gas here will be the atom and when we are dealing with the mole fraction then the value corresponding to the gas here will be the mole fraction After we have the definition of the mole we will learn about the second definition which is related to the mole fraction Here, the mole fraction of an atom is the mole fraction which is equal to the gas unit of the atom N or the mole fraction of that atom So, we will see another point here When we talk about the mole fraction or the mole fraction the unit of it is the carbon unit, right? But in this case, the mole fraction of the gas is equal to the unit of the gas corresponding to N mole fraction or N mole fraction which means corresponding to 6 into 10 to the power of 23 mole fraction or corresponding to 6 into 10 to the power of 23 mole fraction and so on And from there, we can determine that the mole fraction is equal to the unit of the atom or the mole fraction but the unit we are talking about here is the gram For example, here the mole fraction of the iron atom is equal to 56 grams per mole or the mole fraction of the aluminum atom is equal to 32 grams per mole For the atom, we have the mole fraction of the nickel atom is equal to 28 grams per mole and the mole fraction of the arsenic atom is equal to 98 grams per mole So, the mole fraction will be determined by taking the unit of the mole fraction of each compound into the next element We can learn about another data related to the mole fraction of the gas What is the mole fraction of the gas? The mole fraction is equal to the unit of the atom or the mole fraction of the gas But here, we have to pay attention that the gas is the mole fraction So, we have the most accurate definition related to the mole fraction of the gas The mole fraction of the gas is equal to the unit of the atom or the mole fraction of the gas So, what is the characteristic? In this concept this concept is only related to the value of the mole fraction of the gas It does not depend on the gas, right? So, in the same conditions or in the same conditions of temperature and pressure the mole fraction of any gas will have the same mole fraction Or we can draw an example like this For example, we have the same amount of gas which is 2 moles That is 2 moles of nickel gas and 2 moles of oxygen and we measure at the same temperature and pressure then the mole fraction of 2 moles of nickel gas will be equal to the mole fraction of 2 moles of oxygen Pay attention to this sentence That is, in any condition but with the same temperature and pressure then 2 gases we do not need to care about which gas If there are 2 gases in the same temperature and pressure condition they will have the same mole fraction And in this section we will learn about the characteristics of 2 conditions The first condition is the normal condition The normal condition is the condition at the time we are measuring here that is, the temperature is 20 degrees Celsius and the pressure is 1 ampere then we have the normal condition And with this normal condition 1 mole of gas 1 mole of oxygen will have the corresponding mole fraction of 24 liters Or else we can use the formula that is, Av will be equal to 24 times the value of n This is in the normal condition Pay attention For each equation but the equation for you is the temperature is 20 degrees Celsius and the pressure is 1 ampere we will use the formula Av is equal to n times 24 The value of n here is the mole fraction Now The temperature is 0 degrees Celsius and the pressure is 1 ampere With T is equal to 0 degrees Celsius and the pressure is 1 ampere we will have the standard condition And in our chemistry the standard condition is written as dKTc This is the symbol for the standard condition And in the standard condition the mole fraction of the gas is equal to 22.4 liters So we will use the equation that is V is equal to n times 22.4 It is in the standard condition So in the mole fraction of the gas we will have the value of each mole in the normal condition is 24 liters And in the standard condition each mole of gas is equal to 22.4 liters We will go to some exercises to strengthen the 18th equation which is the mole equation What is the first question? I will tell you the number of atoms or mole fractions in each column In column A, there are 0.75 atoms of iron In column B, there are 0.25 atoms of calcium carbonate In column C, there are 0.05 atoms of oxygen To solve the first question, we have to recall the concept of mole The number of atoms in column A, B, C is equal to the number of moles in column A, B, C The number of moles in column A, B, C is equal to the number of moles in column A, B, C The number of moles in column A, B, C is equal to the number of moles in column A, B, C In column C, there are 0.75 atoms of iron There are 0.75 atoms of iron So, the value is 0.75, divided by 6, times 10, which is 23 So, the value is 0.75, divided by 6, times 10, This is also a prime number, which is a small part. The small part is 0.25 carbonate carbonate. 0.25 moles of carbonate carbonate. It will contain 0.25 times 6 times 10 times 23. So the value is 0.25 times 6 times 10 times 23. 1.5 times 10 times 23. And the last one is a mole. So the next one is also a mole of carbonate carbonate. Finally, in the C part, 0.05 moles of oxygen molecule. It will contain 0.05 times 6 times 10 times 23. So it's 0.05 times 6 times 10 times 23. 3 times 10 times 22 oxygen molecules. That's how to calculate the number of atoms or molecules with a mole value. Or there are exercises that require you to calculate the number of atoms and molecules, but not the number of moles, but the number of particles or molecules. We will need to learn the next lesson to be able to determine. Finally, we will move on to the second question. Calculate the particles in the standard conditions of the following atoms. The first question is 0.25 moles of carbonate or carbonate. And the second question is 0.5 moles of oxygen molecules. So to answer the second question, I will have to remember what it is. It is the mole ratio corresponding to the standard conditions. In the standard conditions, a mole of gas or a mole of gas molecule will correspond to 22.4 liters. So the formula used is V will be equal to 22.4 times the value of N. It is the formula in the standard conditions. So in the first part, we have the mole ratio of 0.25 moles of SO2 molecules. In the standard conditions, V of SO2 will be equal to 0.25 times 22.4. 0.25 multiplied by 22.4. So the value is 5.6 liters. The second part is the mole ratio of 0.5 moles of oxygen molecules. In the standard conditions, it will be V of oxygen will be equal to 0.5 times 22.4. So the value is 11.2 liters. So with the second question, we just need to remember the formula. The mole ratio in the standard conditions is calculated by the formula. It is 22.4 times the value of the mole ratio is N. So we can complete the second part. Let's continue with the third question. Find the mole ratio or mole fraction of the following elements. A is 0.5N of chlorine, 2.5N of N2O5, b-butyl and pentoxide. B is 30 or 10.23 of sodium chloride, 1.5 or 10.23 of calcium oxide and CaO. To answer this question, you will see that there is a formula that we can use to define the mole ratio. The mole ratio is the ratio of the element N to the element 6x10.23. To calculate the mole ratio, we use the following formula. N is equal to the number of elements or the number of elements. We divide it by the value of the element. This is the formula that we can use in the third part. Or when you have a similar question, use the formula I just wrote. So with the small a, we will have the first ratio is 0.5N of chlorine. So we will have 0.5N of chlorine. The number of elements is 0.5N divided by the value of N. So it will be equal to 0.5 moles. The next part is 2.5N of nitrogen. 2.5N of nitrogen. Nitrogen is N2O5. So it will have the mole ratio is 2.5N divided by the value of N which is equal to 2.5 moles. The next part is part B. In part B, the formula does not give the element N anymore, but gives the specific values ​​of the element. So we will have 30 times 10 to the power of 23 moles of chlorine. So we will have the mole ratio is 30 times 10 to the power of 23 moles of chlorine divided by 6 times 10 to the power of 23 moles of chlorine. 10 to the power of 23 and 10 to the power of 23. That is, the whole word and the symbol must intersect. 30 times 6 is equal to 5 moles. Similarly, in the last part, we have 1.5 times 10 to the power of 23 moles of chlorine. Calcium is CaO. So the mole ratio is 1.5 times 10 to the power of 23 moles of chlorine divided by 6 times 10 to the power of 23 moles of chlorine. 10 to the power of 23, 10 to the power of 23. So I will just take 1.5 divided by 6. 1.5 divided by 6 equals 0.25 moles. This is the way to do our question number 3. And I hope that this question will not make it difficult for us to understand the nature of the mole concept. And this question number 3 is also the answer to the question number 18, which is about moles. I hope that in this question number 18, you will remember what the mole concept is, what is the mole ratio of molecules, as well as the mole ratio of the molecules. Science in books. The choice of 2 million parents and students. Experience the science of books right away.