Table of Contents
The article provides readers with the most detailed general information about chemical balance and chemical balance as well as how to apply the principle of Lo Sai-Lua to judge the chemical balance. Let's find out with Shining Home – Gia đình Anh Ngữ now!
What is chemical balance? One -way reaction and reversible reaction
To understand what chemical balance is, we will learn about a one -way reaction and reversible reaction.
What is one -way reaction?
Clarify the concept of a one -way reaction, we will consider the following reaction:
2KClO3 -> 2KCl + 3O2 (Condition: MNO2, Temperature)
When heating the potassium chlorate crystals (KCLO3), there is a dioxide catalyst (MNO2), KCLO3 will decompose into potassium chloride (KCl) and oxygen (O2). Also under that condition, potassium chloride (KCl) and oxygen (O2) cannot react with each other to recreate KClO3. Thus, the reaction occurs only in one direction from left to right, such a reaction is called a one -way reaction.
In the chemical equation of a one -way reaction, an arrow indicates the reaction.
Radio reaction
To clarify the concept of reversible reaction? We will consider the following reaction:
Cl2 + H2O ⇌ HCl + HCLO
Under normal conditions, Cl2 will react with water (H2O) to form HCl and HCLO, and HCl and HCLO are also acting together to create Cl2 and H2O. Thus, under the same conditions, the reaction occurs in two opposite directions. Such a reaction is called reversible reaction.
In the chemical equation of the reversible reaction, people use the arrow in the opposite direction instead of the arrow for a one -way reaction.
What is chemical balance?
Chemistry textbook 10 (Vietnam Education Publishing House) has defined in detail the chemical balance as follows: “Chemical balance is a state of reversible reaction when the reaction rate is equal.
To better understand this concept, we will consider the following reversible reaction:
H2 (k) + I2 (k) ⇌ 2hi (k)
Add H2 and I2 to a closed bottle at high temperatures and constant. At first, the reaction speed (VT) is large because of the large concentration of H2 and I2, while the reaction rate is inversely (VN), because the concentration of Hi is zero. During the reaction, the concentration of H2 and I2 decreases so VT decreases and Vietnam will increase gradually due to the increasing HI concentration. At some point, VT becomes equal to Vietnam, then the concentration of substances in the reaction above is kept, if the temperature does not change. This state of the reversible reaction is called chemical balance.
In the equilibrium state, it is not a stop reaction, but the reaction and reverse reaction still occurs but at equal speed (VT = VN). This means that in a single time, the concentration of reaction substances decreases as much as the reaction is created by the reaction. Therefore, chemical balance is dynamic balance.
The characteristics of the reversible reaction are non -metabolic reactions into products, so in the equilibrium system, there are always reaction substances and products.
For example, add 0.5 mol/l H2 and 0.5 mol/l I2 into a closed bottle at a temperature of 430 degrees C. If the reaction is one -way, H2 and I2 will react to form 1 mol/l hi. However, this is a reversible reaction, so it only obtains 0.786 mol/l Hi and the remaining 0.107 mol/l H2, 0.107 mol/l I2.
Chemical balance
Perform the experiment to install the tools including two branch tubes with branches (A) and (B), connected by a soft plastic tube, with an open K lock. Continue to fill the NO2 gas into both tubes (A) and (B) at normal temperature. The closed button of both tubes, including the following balance:
2NO2 (k – reddish brown) ⇌ N2O4 (gas – colorless)
The color of the gas mixture in equilibrium in both tubes (A) and (b) is the same. Perform the K lock to prevent air in the two diffuse tubes together. Soak the tube (A) in the ice water for a while later to compare the color in the tube (A) with the tube (B) noticed that the tube (A) has a lighter color.
When cooling the tube (A), the NO2 molecules in the tube reacted to create N2O4, reducing NO2 concentration and increased N2O4 concentration. That phenomenon is called chemical balance.
Conclude: The chemical balancing shift is the movement from one equilibrium to another due to the impact of external factors on equilibrium. (SGK Chemistry 10, page 158, Vietnam Education Publishing House).
Factors affecting chemical balance
The elements that make balanced shift are concentration, pressure and temperature. They are called factors that affect chemical balance. Specifically as follows:
Effect of concentration
Consider the following balance system in a closed tank at high temperatures and constant:
C (r) + CO2 (k) ⇌ 2CO (k)
When the reaction system is in equilibrium, meaning VT = VN, the concentration of substances in the reaction is not changed anymore. If we add a system of CO2, the CO2 concentration in the system will increase to make gay selection at that time VT with VN, at that time the equilibrium is set. In a new equilibrium state, the concentration of substances will be different from the old equilibrium.
So when adding CO2 to the equilibrium system, the equilibrium will shift from left to right (in the direction of agreement), the direction reduces the concentration of CO2 added. The equilibrium movement occurs the same when we remove the CO from the balance, because then VN <VT. On the contrary, if we add CO in or remove CO2 from the balance system, then VT <VN, the equilibrium will move from right to left (in the opposite direction), meaning that in the direction of reducing CO concentration or increasing the concentration of CO2.
Conclusion: When increasing or decreasing the concentration of a substance in equilibrium, equilibrium always shifts in the direction to reduce the impact of increasing or decreasing the concentration of that substance. In case the balance system is solid in pure form, the addition or removal of solids does not affect the balance, that is, the balance does not move.
Effect of pressure
Consider the underly balanced system in a closed cylinder with plastic piston at normal and constant temperature:
N2O4 (k) ⇌ 2no2 (k)
The experiment proves that when the system is in a state of equilibrium, if the general pressure increases the system, by pushing the piston in to let the general volume of the system decrease, the number of moles of NO2 gas will reduce, and the number of moles of N2O4 gas will increase, that is, the balance of shift in the opposite direction.
Conclude: When increasing or decreasing the overall pressure of the equilibrium system, the equilibrium always shifts in the direction to reduce the impact of increased or decreasing that pressure.
Thus, if the reaction has the number of moles of gas in the two sides of the equal chemical equation or the reaction does not have gas, the pressure does not affect balance. For example, the pressure to the following equilibrium:
H2 (k) + I2 (k) ⇌ 2hi (k)
Fe2O3 (R) + 3CO (K) ⇌ 2Fe (R) + 3CO2 (K)
Effect of temperature
To study the effects of temperature on chemical balance we need to know the concept of heat radiation reaction and heat collection reaction.
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Thermal radiating reaction: is a chemical reaction that is often accompanied by the release or absorption of energy in the form of heat. For example, for high lime to work with H2O water, the mixture forms boiling.
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Heat collection reaction: A chemical reaction we must constantly provide heat for that reaction. For example: Performing limestone (CaCO3) to produce lime.
To indicate the amount of heat accompanied by chemical reactions, people use the reaction quantity, symbolized ΔH <0. In the radiating reaction, the reactions of energy loss so the value ΔH 0 (positive value).
To study the effects of temperature on chemical balance, consider balance in closed tanks:
N2O4 (gas – colorless) ⇌ 2NO2 (gas – reddish brown); ΔH = 58 kJ
Heat collection reaction ΔH = 58 kJ> 0; Radio reaction to radiate heat ΔH = -58 kJ <0
Conclude:
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When the temperature increases, the balance of the heat reaction is shift, that is, the direction of reducing the impact of increasing temperature and when reducing the temperature, balancing the shift in the direction of the heat reaction, the direction reduces the impact of reducing the temperature.
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Three factors of concentration, pressure and temperature affecting chemical balance have been summarized by French chemist H. Le Chatelier into the principle of Satar's balance of balance: “A reversible reaction is in a state of equilibrium when subjected to an impact from the outside such as changing concentration, pressure, temperature, the equilibrium will shift in the direction that reduces the external impact.” (According to chemistry textbook 10, page 161).
The participation of catalysts
The catalyst increases the reaction speed and the reaction rate inversely reach the equal number. Therefore, the catalyst does not affect chemical balance. When the reversible reaction is not in equilibrium, the catalyst has the effect of making equilibrium set faster.
See also:
- Collection of the latest chemical elements 8 9 10
- What is oxidation? 4 rules to determine the oxidation number of 1 element
Meaning of reaction speed and chemical balance in chemical production
To see the meaning of the reaction speed and chemical balance in chemical production, we take the following example:
For example: In the production of sulfuric acid, the following reaction must be performed:
2SO2 (k) + O2 (k) ⇌ 2SO3 (k)
In this reaction, people use air oxygen.
At normal temperature, the reaction occurs very slowly. Therefore, to increase the reaction speed, the catalyst must be used and perform the reaction at a high temperature. Because this is a heat reaction, when the temperature increases, the balance of the shift in the opposite direction reduces the effectiveness of the reaction. To limit this effect, people have used an air residue, meaning increasing the concentration of oxygen, causing balance to move in the right direction.
Exercise on chemical balance textbook Chemistry 10 with detailed solutions
Based on the theoretical knowledge of Shining Home – Gia đình Anh Ngữ has summarized from the textbook 10 above, please continue to practice homework and compare with the detailed answers!
Lesson 1 (SGK Chemistry 10, page 162)
Which of the following is true:
A. Any reaction must reach chemical equilibrium.
B. When the response is reversible in the equilibrium state, the reaction stops.
C. Only reversible reactions have chemical equilibrium.
D. In equilibrium, the mass of substances in the two sides of the reaction equation must be equal.
Suggestions for the answer:
The correct answer is C.
Lesson 2 (SGK Chemistry, page 162)
The following balance system is done in closed flasks:
2SO2 (k) + O2 (k) ⇄ 2SO3 (k) ΔH <0
Which of the following factors does not cause the concentration of substances in the balanced system?
A. Temperature change.
B. Pressure transformation.
C. The presence of catalysts.
D. Change the capacity of the reaction tank.
Suggestions for the answer:
The answer is C. The presence of catalyst. The catalyst increases the reaction speed and the reaction speed inversely have the same number of times. Therefore, the catalyst does not shift the chemical balance or does not cause the concentration of substances in the change
Lesson 3 (SGK Chemistry 10, page 163)
What is chemical balance? Why say chemical balance is dynamic balance?
Suggestions for the answer:
Chemical balance is a state of reversible reaction when the reaction rate is equal to the reaction rate.
Chemical equilibrium is dynamic balance because: In the equilibrium state is not a stop reaction, but the reversible reaction and reversible reaction still occur, but the speed is equal (v consensus = V inverse). This means that in a unit of time the number of moles of reactions decreases as much as the reaction is produced by the inverse reaction. Therefore chemical balance is dynamic balance.
The above is a summary of theoretical details and some chemical balance exercises. I wish you effective review and high results in learning!
Reference source
Exothermic, Endothermic, & Chemical Change – Accessed date: 08/06/2022
https://highschoolenergy.acs.org/content/hsef/en/how-can-energy-change/exothermic-endothermic-chemical-change.html
Endothermic vs exothermic reactions
https://chemistrytalk.org/endothermic-vs-exothermic-ractions/
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