STOICHIOMETRY
STOICHIOMETRYIn chemistry, stoichiometry (sometimes called stoichiometry of reaction to distinguish it from compositional stoichiometry) is a science that studies and quantifies quantitative relationships of reactants and products in chemical reactions (chemical equations). This word comes from the Greek stoikheion (element) and metriā (size).Stoichiometry is based on the basic laws of chemistry, namely the law of conservation of mass, the law of fixed comparison, and the law of multiple comparisonsEarly Stoichiometric Stages In early chemistry, the quantitative aspects of chemical change, ie stoichiometry of chemical reactions, did not receive much attention. Even when attention has been given, experimental techniques and tools do not produce the correct results.
One example involves the theory of flogstones. Flogistonis tried to explain the phenomenon of burning with the term "combustible substances". According to the flogitonists, combustion is the release of a combustible substance (from a burning substance). This substance is then called "flogiston". Based on this theory, they define combustion as a flogiston release of a combustible substance. Changing the mass of wood when burning fits well with this theory. However, changes in metal mass when calcined do not match this theory. Nevertheless flogistonis accept that both processes are essentially identical. Increasing the mass of calcined metals is a fact. Flogistonis attempts to explain this anomaly by stating that flogiston has a negative mass.
Philosopher from Flanders Jan Baptista van Helmont (1579-1644) conducted a famous "willow" experiment. He grows willow seeds after measuring the mass of the flowerpot and the soil. Since there is no change in the masses of flower pots and soil when the seeds grow, he assumes that the mass obtained only by the water entering the ore. He concludes that "the root of all matter is water". Based on the current view, the hypothesis and experiments are far from perfect, but the theory is a good example of the growing demeanor of quantitative chemical aspects. Helmont recognized the importance of stoichiometry, and clearly preceded his time.In the late 18th century, German chemist Jeremias Benjamin Richter (1762-1807) discovered the equivalent concept (in terms of modern chemical equivalent chemistry) with a careful observation of the acid / base reaction, ie the quantitative relationship between acid and base in the neutralization reaction. Richter equivalents, or what are now called chemical equivalents, indicate a certain amount of matter in the reaction. An equivalent in neutralization is related to the relationship between a number of acids and a number of bases to neutralize them. Proper knowledge of equivalents is essential to produce good soap and gunpowder. So, this kind of knowledge is very important in practical terms.
At the same time Lavoisier establishes the law of conservation of mass, and provides the basic concepts equivalent to its accurate and creative experiments. Thus, the stoichiometry that handles quantitative aspects of chemical reactions becomes a basic chemical methodology. All fundamental laws of chemistry, from the law of conservation of mass, the law of comparison remained until the laws of gas reaction were all grounded stoichiometry. These fundamental laws form the basis of atomic theory, and are consistently explained by atomic theory. However, it is interesting to note that, the equivalent concept was used before the atomic theory was introduced.CHEMICAL CALCULATION (STOIKIOMETRY)
A. Determination of Reaction and Reaction Gas VolumeQuestions arising after Gay Lussac put forth the law The volume ratio can be solved by an Italian physicist who Named Amadeo Avogadro in 1811. According to Avogadro: "Gases of the same volume, if measured at temperatures and pressures Same, will have the same number of molecules ". Therefore the ratio of the volume of hydrogen gas, oxygen gas, and water vapor In the reaction of vapor formation = 2: 1: 2 then the ratio of the number of molecules Hydrogen, oxygen, and water vapor are also 2: 1: 2. The number of atoms of each element is not MDecreases or increases in chemical reactions. Therefore, the gas molecule Hydrogen and oxygen gas molecules must be dwiatom molecules,Whereas the water vapor molecule must be a triathome molecule. The ratio of gas volume in a reaction according to the reaction coefficient The gases. This means that, if the volume of one of the gases is known,Other gas volumes can be determined by comparing the coefficients Reactions.
Example:In the reaction of moisture formation.2H2 (g) + O2 (g) -> 2H2O (g)If the volume of H2 gas measured at 25 ° C and 1 atm pressure of 10 L of O2 and H2O gas at the same pressure and temperature can be determined in the following manner.Volume H2: Volume O2 = Coefficient H2: Coefficient O2.
B. Relative Atomic Mass and Relative Molecular Mass
Having discovered highly sensitive equipment in the early twentieth century, chemists experimented on the mass of one atom. For example, experiments were performed to measure.1. mass of one atom H = 1,66 -> 10-24 g2. mass of one atom O = 2.70 -> 10-23 g3. mass of one atom C = 1.99 -> 10-23 gFrom the data above can be seen that the mass of one atom is very small. The experts agreed to use the amount of Atomic Mass Unit (sma) or Atomic Mass Unit (amu) or commonly called also units of Dalton. In the matter of atomic structure,You have also learned that atoms are very small, therefore it is impossible to weigh atoms using a balance sheet.
1. Relative Atomic Mass (Ar)
Experts use the C-12 carbon isotope as standard with a relative atomic mass of 12. The relative atomic mass represents the average mass ratio of one atom of an element to 1/12 of the C-12 atomic mass. Or it can be written:
1 unit of atomic mass (amu) = 1/12 mass 1 atom C-12
Example:
The average atomic mass of oxygen is 1.33 times greater than that of the carbon-12 atoms.Experts use the C-12 carbon isotope as standard with a relative atomic mass of 12. The relative atomic mass represents the average mass ratio of one atom of an element to 1/12 of the C-12 atomic mass. Or it can be written:1 unit of atomic mass (amu) = 1/12 mass 1 atom C-12Example:The average atomic mass of oxygen is 1.33 times greater than that of the carbon-12 atoms. Then: Ar O = 1.33 -> Ar C-12
= 1.33 -> 12
= 15.96
Experts compare different atomic masses, using the relative atomic mass scale with the symbol "Ar".
The experts decided to use C-12 or 12C isotope because it has an inert core stability compared to other atoms. The isotope of C-12 atom has an atomic mass of 12 sma. One sma equals 1.6605655 x 10-24 g. With the use of 12C isotope as standard then can be determined the mass of atom of other element. The relative atomic mass of an element (Ar) is a declaring number. The mass ratio of one atom of that element to 1/12 mass of one C-12 atom.
ArX = (average atomic mass X) / (1/2 mass of carbon atom - 12)
Multiple Isotope Mask Table= 1.33 -> 12= 15.96Experts compare different atomic masses, using the relative atomic mass scale with the symbol "Ar".The experts decided to use C-12 or 12C isotope because it has an inert core stability compared to other atoms. The isotope of C-12 atom has an atomic mass of 12 sma. One sma equals 1.6605655 x 10-24 g. With the use of 12C isotope as standard then can be determined the mass of atom of other element. The relative atomic mass of an element (Ar) is a declaring number. The mass ratio of one atom of that element to 1/12 mass of one C-12 atom.ArX = (average atomic mass X) / (1/2 mass of carbon atom - 12)Multiple Isotope Mask TableProblems example:If it is known that the mass of 1 oxygen atom is 2.70 x 10-23 g, what is the Ar atom O ifAtomic mass C 1,99 x 10-23 g?Answer:The magnitude of the Ar price is also determined by the average price of the isotope. For example, in nature there are 35Cl and 37Cl with a ratio of 75% and 25% then Ar Cl can be calculated by:Ar Cl = (75% x 35) + (25% x 37) = 35.5Ar is a comparative number so it has no units. Ar can be seen in the Periodic Table of the Elements (TPU) and always included in the unit of questions if necessary2. Molar Volume (Vm)
The volume of one mole of a substance in a gas form is called the molar volume, denoted by Vm.What is the volume of gas molar? How to calculate the volume of a certain amount of gas at a certain temperature and pressure?Avogadro in his experiments concluded that 1 L of oxygen gas at 0 ° C and 1 atm pressure had a mass of 1.4286 g, or it could be stated that at 1 atm pressure:Thus, under Avogadro's law it can be concluded:1 mol of gas O2 = 22.4 LIn accordance with Avogadro's law stating that at the same temperature and pressure, the same volume of gas contains the same number of molecules or the number of moles of each gas volume the same. Under the law, a volume of 1 mole of each gas in standard conditions (0 ° C and 1 atm pressure) is applied. Volume gas in standard state = 22.4 L3. Gas Volume in Non-Standard StateCalculation of gas volume is not in the standard state (non-STP) used the following two approaches.A. The ideal gas equationAssuming the gas to be measured is ideal, the equation that links the number of moles (n) of gas, pressure, temperature, and volume that is:The ideal gas law: P. V = n. R. TWhere:P = pressure (atmospheric unit, atm)V = volume (liters, L)N = number of moles of gas (mol unit)R = gas constant (0.08205 L atm / mol K)T = absolute temperature (° C + 273.15 K) 4. Molarity (M) The amount of substances present in a solution can be determined by using the concentration of the solution expressed in molarity (M). Molarity states the number of moles of substances in 1 L of solution. Mathematically stated as follows.Where:
M = molarity (unit M) Mr. = molar mass (unit g / mol)
V = volume (mL unit) Mass = in units gM = molarity (unit M) Mr. = molar mass (unit g / mol)V = volume (mL unit) Mass = in units g
One example involves the theory of flogstones. Flogistonis tried to explain the phenomenon of burning with the term "combustible substances". According to the flogitonists, combustion is the release of a combustible substance (from a burning substance). This substance is then called "flogiston". Based on this theory, they define combustion as a flogiston release of a combustible substance. Changing the mass of wood when burning fits well with this theory. However, changes in metal mass when calcined do not match this theory. Nevertheless flogistonis accept that both processes are essentially identical. Increasing the mass of calcined metals is a fact. Flogistonis attempts to explain this anomaly by stating that flogiston has a negative mass.
Philosopher from Flanders Jan Baptista van Helmont (1579-1644) conducted a famous "willow" experiment. He grows willow seeds after measuring the mass of the flowerpot and the soil. Since there is no change in the masses of flower pots and soil when the seeds grow, he assumes that the mass obtained only by the water entering the ore. He concludes that "the root of all matter is water". Based on the current view, the hypothesis and experiments are far from perfect, but the theory is a good example of the growing demeanor of quantitative chemical aspects. Helmont recognized the importance of stoichiometry, and clearly preceded his time.In the late 18th century, German chemist Jeremias Benjamin Richter (1762-1807) discovered the equivalent concept (in terms of modern chemical equivalent chemistry) with a careful observation of the acid / base reaction, ie the quantitative relationship between acid and base in the neutralization reaction. Richter equivalents, or what are now called chemical equivalents, indicate a certain amount of matter in the reaction. An equivalent in neutralization is related to the relationship between a number of acids and a number of bases to neutralize them. Proper knowledge of equivalents is essential to produce good soap and gunpowder. So, this kind of knowledge is very important in practical terms.
At the same time Lavoisier establishes the law of conservation of mass, and provides the basic concepts equivalent to its accurate and creative experiments. Thus, the stoichiometry that handles quantitative aspects of chemical reactions becomes a basic chemical methodology. All fundamental laws of chemistry, from the law of conservation of mass, the law of comparison remained until the laws of gas reaction were all grounded stoichiometry. These fundamental laws form the basis of atomic theory, and are consistently explained by atomic theory. However, it is interesting to note that, the equivalent concept was used before the atomic theory was introduced.CHEMICAL CALCULATION (STOIKIOMETRY)
A. Determination of Reaction and Reaction Gas VolumeQuestions arising after Gay Lussac put forth the law The volume ratio can be solved by an Italian physicist who Named Amadeo Avogadro in 1811. According to Avogadro: "Gases of the same volume, if measured at temperatures and pressures Same, will have the same number of molecules ". Therefore the ratio of the volume of hydrogen gas, oxygen gas, and water vapor In the reaction of vapor formation = 2: 1: 2 then the ratio of the number of molecules Hydrogen, oxygen, and water vapor are also 2: 1: 2. The number of atoms of each element is not MDecreases or increases in chemical reactions. Therefore, the gas molecule Hydrogen and oxygen gas molecules must be dwiatom molecules,Whereas the water vapor molecule must be a triathome molecule. The ratio of gas volume in a reaction according to the reaction coefficient The gases. This means that, if the volume of one of the gases is known,Other gas volumes can be determined by comparing the coefficients Reactions.
Example:In the reaction of moisture formation.2H2 (g) + O2 (g) -> 2H2O (g)If the volume of H2 gas measured at 25 ° C and 1 atm pressure of 10 L of O2 and H2O gas at the same pressure and temperature can be determined in the following manner.Volume H2: Volume O2 = Coefficient H2: Coefficient O2.
B. Relative Atomic Mass and Relative Molecular Mass
Having discovered highly sensitive equipment in the early twentieth century, chemists experimented on the mass of one atom. For example, experiments were performed to measure.1. mass of one atom H = 1,66 -> 10-24 g2. mass of one atom O = 2.70 -> 10-23 g3. mass of one atom C = 1.99 -> 10-23 gFrom the data above can be seen that the mass of one atom is very small. The experts agreed to use the amount of Atomic Mass Unit (sma) or Atomic Mass Unit (amu) or commonly called also units of Dalton. In the matter of atomic structure,You have also learned that atoms are very small, therefore it is impossible to weigh atoms using a balance sheet.
1. Relative Atomic Mass (Ar)
Experts use the C-12 carbon isotope as standard with a relative atomic mass of 12. The relative atomic mass represents the average mass ratio of one atom of an element to 1/12 of the C-12 atomic mass. Or it can be written:
1 unit of atomic mass (amu) = 1/12 mass 1 atom C-12
Example:
The average atomic mass of oxygen is 1.33 times greater than that of the carbon-12 atoms.Experts use the C-12 carbon isotope as standard with a relative atomic mass of 12. The relative atomic mass represents the average mass ratio of one atom of an element to 1/12 of the C-12 atomic mass. Or it can be written:1 unit of atomic mass (amu) = 1/12 mass 1 atom C-12Example:The average atomic mass of oxygen is 1.33 times greater than that of the carbon-12 atoms. Then: Ar O = 1.33 -> Ar C-12
= 1.33 -> 12
= 15.96
Experts compare different atomic masses, using the relative atomic mass scale with the symbol "Ar".
The experts decided to use C-12 or 12C isotope because it has an inert core stability compared to other atoms. The isotope of C-12 atom has an atomic mass of 12 sma. One sma equals 1.6605655 x 10-24 g. With the use of 12C isotope as standard then can be determined the mass of atom of other element. The relative atomic mass of an element (Ar) is a declaring number. The mass ratio of one atom of that element to 1/12 mass of one C-12 atom.
ArX = (average atomic mass X) / (1/2 mass of carbon atom - 12)
Multiple Isotope Mask Table= 1.33 -> 12= 15.96Experts compare different atomic masses, using the relative atomic mass scale with the symbol "Ar".The experts decided to use C-12 or 12C isotope because it has an inert core stability compared to other atoms. The isotope of C-12 atom has an atomic mass of 12 sma. One sma equals 1.6605655 x 10-24 g. With the use of 12C isotope as standard then can be determined the mass of atom of other element. The relative atomic mass of an element (Ar) is a declaring number. The mass ratio of one atom of that element to 1/12 mass of one C-12 atom.ArX = (average atomic mass X) / (1/2 mass of carbon atom - 12)Multiple Isotope Mask TableProblems example:If it is known that the mass of 1 oxygen atom is 2.70 x 10-23 g, what is the Ar atom O ifAtomic mass C 1,99 x 10-23 g?Answer:The magnitude of the Ar price is also determined by the average price of the isotope. For example, in nature there are 35Cl and 37Cl with a ratio of 75% and 25% then Ar Cl can be calculated by:Ar Cl = (75% x 35) + (25% x 37) = 35.5Ar is a comparative number so it has no units. Ar can be seen in the Periodic Table of the Elements (TPU) and always included in the unit of questions if necessary2. Molar Volume (Vm)
The volume of one mole of a substance in a gas form is called the molar volume, denoted by Vm.What is the volume of gas molar? How to calculate the volume of a certain amount of gas at a certain temperature and pressure?Avogadro in his experiments concluded that 1 L of oxygen gas at 0 ° C and 1 atm pressure had a mass of 1.4286 g, or it could be stated that at 1 atm pressure:Thus, under Avogadro's law it can be concluded:1 mol of gas O2 = 22.4 LIn accordance with Avogadro's law stating that at the same temperature and pressure, the same volume of gas contains the same number of molecules or the number of moles of each gas volume the same. Under the law, a volume of 1 mole of each gas in standard conditions (0 ° C and 1 atm pressure) is applied. Volume gas in standard state = 22.4 L3. Gas Volume in Non-Standard StateCalculation of gas volume is not in the standard state (non-STP) used the following two approaches.A. The ideal gas equationAssuming the gas to be measured is ideal, the equation that links the number of moles (n) of gas, pressure, temperature, and volume that is:The ideal gas law: P. V = n. R. TWhere:P = pressure (atmospheric unit, atm)V = volume (liters, L)N = number of moles of gas (mol unit)R = gas constant (0.08205 L atm / mol K)T = absolute temperature (° C + 273.15 K) 4. Molarity (M) The amount of substances present in a solution can be determined by using the concentration of the solution expressed in molarity (M). Molarity states the number of moles of substances in 1 L of solution. Mathematically stated as follows.Where:
M = molarity (unit M) Mr. = molar mass (unit g / mol)
V = volume (mL unit) Mass = in units gM = molarity (unit M) Mr. = molar mass (unit g / mol)V = volume (mL unit) Mass = in units g
what is the mole formula?
BalasHapusthanks wandra,,
Hapusok the formula of mole is n=gr/mr
What is the difference between mole and molarity?
BalasHapus• Mole is a measurement of the number of substances, whereas molarity is a measurement of the concentration.
Hapus• Molarity gives an idea of the amount of substances present in a mixture.
• Molarity is given as moles of a substance in one volume of a solvent.
• A mole is a unit whereas molarity is not.
What causes the mass of substances before and after the reaction is the same according lavoiser?
BalasHapusThe law of conservation of mass or otherwise known as Lomonosov-Lavoisier law is a law that states the mass of a closed system will be constant despite the various processes within the system (in a closed system The mass of substances before and after the reaction is the same (constant)) . The commonly used statement to express the law of conservation of mass is that mass can be deformed but can not be created or destroyed. For a chemical process within a closed system, the mass of the reactants must be equal to the mass of the product.
HapusThe law of conservation of mass is widely used in fields such as chemistry, chemical engineering, mechanics, and fluid dynamics. Based on the special science of relativity, mass conservation is a statement of the conservation of energy. The fixed particle mass in a system is equivalent to its central momentum energy. In some radiation events, it is said that the mass changes to energy. This happens when an object changes into kinetic energy / potential energy and vice versa. Since mass and energy are related, in a system that gets / releases energy, a very small amount of mass will be created / lost from the system. However, in almost all events involving changes in energy, mass conservation laws can be used because the changed mass is very small.
what is the stoiciometry?
BalasHapusSTOICHIOMETRYIn chemistry, stoichiometry (sometimes called stoichiometry of reaction to distinguish it from compositional stoichiometry) is a science that studies and quantifies quantitative relationships of reactants and products in chemical reactions (chemical equations). This word comes from the Greek stoikheion (element) and metriā (size).Stoichiometry is based on the basic laws of chemistry, namely the law of conservation of mass, the law of fixed comparison, and the law of multiple comparisonsEarly Stoichiometric Stages In early chemistry, the quantitative aspects of chemical change, ie stoichiometry of chemical reactions, did not receive much attention. Even when attention has been given, experimental techniques and tools do not produce the correct results.
Hapuswhat is Relative Atomic Mass (Ar)?
BalasHapusExperts use the C-12 carbon isotope as standard with a relative atomic mass of 12. The relative atomic mass represents the average mass ratio of one atom of an element to 1/12 of the C-12 atomic mass. Or it can be written:
Hapus1 unit of atomic mass (amu) = 1/12 mass 1 atom C-12