Stoichiometry
Stoichiometry
is a science that studies the quantitative relationship between reactants
(substances before chemical reaction) and products in a chemical reaction.
The concept of mole
Mol: the unit of substance in chemistry
One mole is a number of substances containing 6.02.1023 particle grains.
• One mol element contains 6.02. 1023 grains of atoms
• One mole of the compound contains 6.02. 1023 molecules.
The number of moles is the central terminal of the stoichiometric traffic path. 1 mol of the substance contains 6.022 x 1023 particles
Volume at time T and P
"The volume of one mole of a substance in a gas form is called the molar volume (with the symbol, Vm) of the substance".
P. V = n. R. T
Where:
P = pressure (atmospheric unit, atm)
V = volume (liters, L)
N = number of moles of gas
R = gas constant (0.08205 L atm / mol K)
T = absolute temperature (oC + 273,15K)
According to Avogadro's law:
"At the same temperature and pressure (same TP), the gas mole ratio is equal to the ratio of gas volume"
Vm = 22.4 L
V = n x 22.4 L
Molality: the number of moles of solute in 1 kg of solvent.
Molarity: the number of moles of solute in a liter of solution.
For example a 0.1 M HCl solution means that in each liter of solution there is 0.1 mole of HCl or in every mL of solution there is 0.1 mmol HCl.
• Molarity of a solution with a density of ρ, and P%
• The volume of the solution of the density ρ, the P% required to prepare V (mL) of a molar solution
V1 = Volume of solution required
V2 = Volume of solution to be made
MOLECULES AND CONDITIONS OF THE ELEMENTS IN THE COMPOUND
Chemical formula: A collection of atomic symbols or constituent elements with a certain comparison.
Example:
H2O, CH2O, and C2H6O.
Empirical Formulas: the chemical formula which expresses the smallest composition of the elements that make up the compound.
The mole ratio of the element expresses the empirical formula.
Examples of the empirical formulas are: H2O, C¬H2O, C2H6O and others.
Elemental Content in Compound
The
ratio of mass and elemental content in a compound can be determined from its
molecular formula.
Mixing Different Concentrations: mixing two or more similar solutions of different concentrations to obtain the desired concentration
Dilution: addition of water into the solution so that the concentration is lower. At dilution, the volume and the solubility of the solution change, but the number of moles of solute does not change (fixed).
V1 = initial solution volume
M1 = initial kemolaran
V2 = volume of solution after dilution
M2 = dilution of solution after dilution
Give me one example problem by applying the molarity formula
BalasHapusOkay nurul I will give examples of the questions along with answers about the molarity formula.
HapusDetermine the molarity of a solution comprising 17.1 grams of sugar (C12H22O11) in 0.25 liters of solution.
Answer:
Is known:
Mass = 17.1 gr
Mr. C12H22O11 = 342 gr / mol
V = 0.25 L
Asked: M =?
Resolution:
Number of moles C12H22O11 = mass / Mr
The number of moles of C12H22O11 = 17.1 g / (342 g / mol)
The number of moles of C12H22O11 = 0.05 mol
M = number of moles / V
M = 0.05 mol / 0.25 L
M = 0.2 mol / L
What's the use of Atomic mass?
BalasHapusThe atomic mass can be used to determine the amount of mass of protons, neutrons, and electrons in an atom.
HapusHow the concept of stoichiometric material?
BalasHapusThe subject of stoichiometry involves quantitative calculations based on chemical formulas and chemical equations.
Hapus1. Molecular Mass and Mass Formula
The molecular mass and mass formula is the mass expressed in the atomic mass (u) of the individual molecule and the compound element. All are calculated from the atomic mass in the empirical formula or molecular formula. The molecular mass is applicable only to molecular compounds, the mass formula used for ionic compounds.
2. Mol and Avogadro numbers
One mole is the number of particles relative to 12 g of carbon-12. This number is called the Avogadro number of 6.022 × 1023 mol-1. Mol is an SI unit for the amount of substances and is widely used in chemical equations and calculations.
3. Mole mass and molar mass
The mass of one mole of matter is referred to as the molar mass. Conversion between the number of moles and the number of grams of substances requires a molar mass as a conversion factor. Calculations involving volume, density, and number of atoms or molecules can also be used to determine molar numbers.
4. Composition of Percent Mass
The mass percentage of individual elements in a compound can be determined from the chemical formula and the molar mass.
5. Chemical Formulas of Mass Percent Composition
An empirical formula can be formed from the percent compound mass composition by calculating the molar ratio of the different elements. The empirical formula calculated in this way may be the same as the molecular formula. To make the molecular formula, we must also know the molecular mass.
6. Experiment Determination of Mass Percent Composition
Percent mass of carbon, hydrogen, and oxygen in organic compounds can be determined by combustion analysis. Another method required to determine the percent mass composition is to use inorganic compounds.
7. Writing and Equating Chemical Equations
Chemical equations use symbols and formulas for elements or compounds involved in the reaction. A chemical equation describes the reaction, shown by arrows, from reactants to products. The stoichiometric coefficient is placed before the symbol or formula in the equation to balance the equation. As required by the law of conservation of mass, each element equals both on the product side and on the side of the reactant.
8. Stoichiometry Reaction
Stoichiometry involves a quantitative relationship in chemical reactions. Stoichiometric factors known as the mole ratios are based on coefficients in equivalent equations and are used to connect reactants or products. Molar mass and stoichiometric factors are used to find information about one of the reactants or products in a chemical reaction.
9. Pereksi Pembatas
Limiting reagents are reagents that are completely used in the reaction. The theoretical quantities of the product formed can be determined from the limiting reagents. Other reagents are called excess reagents. In stoichiometry, the limiting reagents must be determined first.
10. Percent Result
Calculated theoretically from reagents. The quantity obtained from chemical reactions, or so-called experimental results, is often less and is generally expressed as a percentage of theoretical results.
Solution and Stoichiometry of Solution
The solution is prepared by dissolving one solute in a solvent. Dissolved substances usually amount to a little lower. Molarity (M) or molar concentration of solution is the number of moles of solute per liter of solution
Dilution is an increase in the volume of solvent. But the amount of solute does not change. As a result, the concentration decreases. Calculation of stoichiometric reactions in solution to frequently use molarity as a conversion factor.
could you explain to me about concept mol?
BalasHapusOkay, i will explain the concept of mole
Hapus1 mole is a unit of chemical number whose number of atoms or molecules is equal to the Avogadro number and its mass = Mr compound.
If the number Avogadro = L then:
L = 6.023 x 1023
1 mol atom = L of atomic fruit, its mass = Ar of the atom.
1 mol molecule = L molecular fruit mass = Mr molecule tersberut.
The mass of 1 mol of substance is called the molar mass of the substance
Example:
How many molecules are there in 20 grams of NaOH?
Answer:
Mr NaOH = 23 + 16 + 1 = 40
Mole NaOH = mass / Mr = 20/40 = 0.5 mol
The number of molecules NaOH = 0.5 L = 0.5 x 6.023 x 1023 = 3.01 x 1023 molecules.
What is the relationship between the molality molarity?
BalasHapusMolarity = mol solute / liter of solution (M = n / V)
HapusMolality = mol solute / kg of solvent (m = n / kg)
What is the molar difference with molal?
BalasHapusMolarity expresses the number of moles of solute in every one liter of solution. Molarity is denoted by M notation and the unit is mol / liter. Whereas Molality or molal concentration (m) represents the amount of solute mole in 1000 grams of solvent.
HapusWhat is relationship between pleasure and temperature?
BalasHapusTemperature symbolized "T" kelvin
HapusThe pressure symbolized "P" pascal
As far as I know the relationship between these two equations
P1 / T1 = P2 / T2 when volume is constant
Or in an ideal gas equation
PV = nRT where V = gas volume, n = mol of gas, R = common gas constant.
Please give an example of dilution
BalasHapusExample:
HapusWhat is the volume of 2 M H2SO4 solution required to prepare a 200 mL H2SO4 0.5 M solution?
Answer:
M1 = 2 M
M2 = 0.5
V 2 = 200 ml
V1 =?
then
M1.V1 = M2.V2
2.V1 = 0.5.200
V1 = 50 ml
Give me example from your formula (P.V=n.R.T)
BalasHapusfor example:
HapusAs much as 0.01 mol of gas is in a 100 liter tank and temperature of 87 ° C. If the gravitational acceleration is 10 m / s2, determine the gas pressure!
Resolution:
Is known:
T = 87 ° C + 273 K = 360 K
V = 100 L = 0.1 m3
N = 0.01 mol
Asked:
What is the pressure (P) of the gas ......?
Answer:
PV = nRT
P (0.1 m3) = (0.01 mol) (8,314 J / kmol K) (360 K)
0.1 P = 29.930 N / m2
P = 299,300 N / m2
= 2.9 x 10-3 atm
Thus, the gas pressure is 2.9 x 10-3 atm.
Why, In chemical reactions, the amount of reactants reacting sometimes does not correspond to the stoichiometric amount of the reaction (not in accordance with the coefficient ratio of the equivalent equation)
BalasHapusHow the relationship between moles with mass, volume, and number of particles?
BalasHapus