STOICHIOMETRY
The word stoichiometry actually comes from two words from the Greek "stoicheion" meaning element and "metron" which means measuring elements. From several literatures and sources many mention stoichiometry is measuring the elements. The broader stoichiometric definitions include a wide range of measurements including substance calculations and chemical mixtures.
1. GAS LAW
For ideal gas apply equation: PV = nRT
Where: P = gas pressure (atmosphere)
V = volume of gas (liter)
N = mol of gas
R = universal gas constant = 0.082 lt.atm / mol Kelvin
T = absolute temperature (Kelvin)
The changes of P, V and T from state 1 to state 2 under certain conditions are reflected by the following laws:
2. COMPARATIVE LAWS = LEGAL DALTON
"If two elements can form two or more compounds for the mass of one element equal to the number then the ratio of the mass of the second element will be proportional to the integer and the simple".
Example:
When the element of Nitrogen with compounded oxygen can be formed,
NO where the mass N: O = 14: 16 = 7: 8
NO2 where the mass N: O = 14: 32 = 7: 16
For the same mass of Nitrogen the Oxygen mass ratio of the compound
NO: NO2 = 8: 16 = 1: 2
Besides, another example is
Nitrogen and Oxygen can form six kinds of compounds.
The ratio of the weight of oxygen that reacts with one part of nitrogen is:
0.57: 1.14: 1.74: 2.28: 2.86: 3.42
1: 2: 3: 4: 5: 6
3. Basic Law of Chemistry
LAW MASS LAW = LAVOISIER LAW
"The mass of substances before and after the reaction is fixed".
Example:
Magnesium + Chlorine -> Magnesium Chloride
1.0 g 2.9 3.9
This comparison is an easy & round number, so it is in accordance with Comparative Laws.
4.
PERSONAL COMPARATIVE LAW = PROUST LEGAL
"The ratio of the
mass of the elements in each compound is fixed"
Example:
A.
In the compound NH3 . . . . . . .. . . . mass N: mass H = 1 Ar. N: 3 Ar. H
=
1 (14): 3 (1)
=
14: 3
B.
On SO3 compound . . . . .mass S: mass O = 1 Ar. S: 3 Ar. O
=
1 (32): 3 (16)
=
32: 48
=
2: 3
Advantages of Proust Law:
When the mass is known a compound or mass of one
element that forms the compound then the mass of other elements can be known.
Example:
What is the level of C in 50 grams CaCO3? (Ar: C =
12, 0 = 16;
Ca=40)
Legal Deviation Irregularities
Isotope
There
are two kinds of compounds with two kinds of weight ratio eg water (ratio of
oxygen-hydrogen 8: 1) and "heavy water" (ratio of oxygen-hydrogen
weight to 8: 2), showing deviations from the fixed order law.
Non-stoichiometric
compounds
The
average composition of Ti0 ranges from Ti0.70 to Ti00,7. Such compounds (Pb
S1,14 and UO2,12) that deviate from the Law of Fixed Arrangement are called
Non-Daltonion, Berthollide or Non-Stoichiometric compounds.
A.
BOYLE LAW
Boyle's law (or often
referenced as Boyle-Mariotte's Law) is one of many chemical laws and is a
special case of the ideal chemical law. Boyle's law describes the inverse
relationship of proportion between absolute pressure and air volume, if the
temperature remains constant in a closed system. This law is named after
chemist and physicist Robert Boyle, who published his original law in 1662. His
own law reads:
"For fixed
quantities the ideal gas remains at the same temperature, P [pressure] and V
[volume] are inverted proportional (where one is double, the other half)"
This law is derived from the
ideal gas state equations with
N1 = n2 and T1 = T2; So
obtained: P1 V1 = P2 V2
Example:
What is the pressure of 0 5 mol of O2 with a volume
of 10 liters if at that temperature 0.5 mole of NH3 has a volume of 5 liters
den with atmospheric pressure?
Answer:
P1 V1 = P2 V2 then 2 x 5 = P2 x 10 → P2 = 1
atmosphere
rams.
B. GAY-LUSSAC LAW
Gay Lussac concludes his invention in a law called volume comparison law, as follows: "When measured at the same temperature and pressure, the volume of the reacting gas and the reaction gas are compared as simple and integers."
So for: P1 = P2 and T1 = T2 apply:
Example:
Calculate the mass of 10 liters of nitrogen gas (N2) if under these conditions 1 liter of hydrogen gas (H2) mass is 0.1 g.
Given: Ar for H = 1 and N = 14
So, the mass of nitrogen gas = 14 g
So, the mass of nitrogen gas = 14 g
C.
BOYLE-GAY LUSSAC LAW
This law is an extension of the previous law den
diturukan with the state price n = n2 so obtained the equation: P1. V1 / T1 =
P2. V2 / T2
D.
AVOGADRO LAW
"At the same temperature and pressure, the same
volume gases contain the same number of molecules.From this statement it is
determined that in STP
(0 degrees C, 1 atm) of 1 mole per volume of 22.4
liters volumes of volume is referred to as the molar volume of the gas.
Example:
What is the volume of 8.5 grams of ammonia (NH3) at
a temperature of 27 degrees C and a pressure of 1 atm? (Ar: H = 1; N = 14)
Answer:
Mol of ammonia = (8,5 / 17) mol = 0,5 mol
Ammonia volume (STP) = 0.5 x 22.4 = 11.2 liters
Based on the Boyle-Gay Lussac equation:
From the following chemical reactions: C4H6 + O2 → CO2 + H2 Mention the reagents and the reactants and adjust the reaction
BalasHapusWhich is a reagent is: C4H6
HapusEquivalent reaction: C4H6 + 4 O2 → 4 CO2 +3 H2
How is the sound of gay lussac law?
BalasHapusThe volume of gases that react with the volume of the gases of the reaction when measured at the same temperature and pressure will be proportional to a simple integer
HapusThere are several laws regulating the stoichiometry, please explain !
BalasHapusThe laws governing Stoichiometry.
BalasHapusThe stoichiometry relies on law is like fixed comparative law, double comparative law and also the law of conservation of the masses.
1. The law of conservation of the masses
Using the laws of physics is like the law of conservation of mass, which holds that the mass of the reactants is equal to the mass of the product, Stoichiometry is used to gather information about the amount of various elements used in a chemical reaction,
2. Comparative law remains
This law states that the chemical compound (a substance consisting of 2 (two) or more ages) which always contains the same proportion of an element (compound with one atom type) with mass.
3. Law of multiple comparison
This law is one of the basic laws of stoichiometry, aside from the law of fixed comparison. Sometimes it is also called Dalton's law. It is said that, if 2 (two) elements form more than one compound between them, then the mass ratio of a second element which joins the fixed mass over the first element of both will have a ratio of a small sum of the whole.
How to find relative atomic mass?
BalasHapusTo determine the relative atomic mass of an element depending on what is in the know an element, the mass with the mole, then it can look for Ar by using the mol formula. That is one example, in fact there are still many ways to determine the relative atomic mass of an element by using the other chemical formula.
Hapuswhy we must to know stoichiometric ??
BalasHapusBecause of the stoichiometry of a subject in chemistry involving the linkage of reactants and products in a chemical reaction to determine the quantity of each reacting agent. In the discussion of stoichiometry also discusses the laws of mass kekekalas, gay lussac law, boyle law and the laws set by the scientists of chemistry, of course it is very important for us to know, because it stoichiometri very important for us to learn.
Hapus