TRABAJO PRACTICO DE QUIMICA GENERAL

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PRINCIPIOS QUIMICOS REVISADOS

Entregado por:

GARCES MARTINEZ JUAN NICOLAS

Codigo:

40161440

Entregado a:

DOCENTE  FERNANDO GONZALES MANIOS

GRUPO NUM. 49

DEPARTAMENTO DE CIENCIAS BASICAS

FACULTDAD DE INGENIERIA

BOGOTA COLOMBIA

2016

Summary

in chemical stoichiometry is the calculation of quantitative relationships between reactants and products during a chemical reaction, these reactions can be deduced starting from the atomic theory. "The measurement of chemical elements" sought a way as mathematics were seen in the chemical involved. Richter then touch the item had mentioned before iodine and aluminum. How many grams of iodine completely react with 10 g of aluminum metal?

And to solve it first needs the atomic weight of each and it is known that the iodine atom weighs almost five times more than the aluminum atom, then divide the 10g aluminum between weight that is 27 by 127 which is the atomic weight of iodine and results 47g, but it is required to find three iodine atoms then multiply 47x3 = 141g, after that it would be best to start in the balanced equation that would 2to + 3 I2 - 2AlI3. In this case a method called "units factor" is an equivalence between a numerator and a denominator is used, it is made to cancel units, when equivalence is done and done operations it is the result of two iodine 141g, and it is said to be better approximate the amounts to use integers in decimal so that the response is accurate.

the word mole was introduced by Wilhelm Ostwald (1896) where he tries to say that a mole is a lot of pile of atoms or molecules, he says a mole is a certain amount of substance that contains six point two zero ten to the twenty-third it will always be the same regardless of the particular substance or composition, and a mole of gas at standard conditions always occupies about the same volume (22.41), regardless of the nature or formula of the gas. The mass of a mole must vary from substance to substance, the molar mass of each substance being its own formula weight expressed in grams. Mol word has many meanings but there are some that are erroneous.

The mole is the SI unit to measure the "amount of substance". The official definition is, A mole is the amount of substance which contains as many elementary particles as there are atoms in 0.012 kg carbón.

The Chemist's Dozen.

is good to compare the mole terms with other groups, for example:

items: socks,dice

kind of set: pair

number in set: two

The mole is then seen to be just another counting unit. It does differ from the others in that the individual items in the set are invisible, and the number making up the set is quite ab-struse, but the principle is still the same.

A very simple but highly effective visual display is an as-sortment of flasks each containing exactly one mole of a substance (12 g of carbon, 24.3 g of magnesium, 58.5 g of sodium chloride, 342 g of sucrose, etc.) plus a dozen styrofoam balls in each of several sizes (1/2 in., 1 in., and 11/2 in. in diameter).

A dozen balls will fill a small beaker or a very large one de-pending on the size of an individual ball. Likewise, a mole of substance will fit in a small flask (carbon) or will require a large one (sucrose) depending on the size of the individual atom or molecule.

How Big Is Avogadro's Number?

It is a very immensely large number when you write with decimals, To convey the magnitude of Avogadro's number we need to use more tangible units.

Avogadro's number is so huge that defies human understanding. Moreover, it is not necessary to be able to understand the Avogadro number in order to use it. There is no reason why 6 ten to the twenty-third can not be treated in the same way that we would try to 6,000, or 6 hundred, or a dozen. The important thing to remember is that, despite its overwhelming size can be, Avogadro's number is still a real and finite number. Avogadro's number is the number of atoms in a gram atomic weight Of any element. The number was predetermined when the gram was established as a basic unit of mass and it becomes very strange that this large number can exist and wonder where it comes from?.

Determination Of Avogadro's Number

Amedeo Avogadro was an Italian physics professor who never knew the numerical value of the constant that bears his name. when he died, his idea that equal volumes of gases contain the same number of molecules (in same conditions) and therefore the weights of the individual molecules must be proportional to their densities of gas. The concept of standard volume molar gas (22.41 in STP) and the concept of mole are direct outgrowths of this hypothesis, then Ampere and Dumas tried to go beyond that idea but thought it would not succeed, later Ger-Hardt (1842) tried to use it to determine the molecular weights of organic compounds, but do not use it well, then an Italian scientist Stanislao Cannizzaro, who succeeded in convincing their colleagues chemical significance of Avogadro's hypothesis.

The idea of ​​thinking substance in terms of "gram-molecules," their molecular weights expressed in grams, was not produced by chemical immediately, but it was clear from Avogadro's hypothesis that such amount should always contain the same number of molecules . The number is supposed to be extremely large, but in order to know how big a first had to know how small it was a molecule.

The first attempt to measure the size of a molecule was Josef Loschmidt who tried to measure the diameter of air molecules by applying the molecular kinetic theory. He found the diameter of being a "millionth of a millimeter," or about 10 Å. Loschmidt could have happened to calculate a value for Avogadro's number, but did not do so. Avogadro constant as calculated from figures Loschmidt was 4.1 X 10 to the twenty, but still not reach the figure were really worth. have been looking many ways to measure the size or the Avogadro constant have become almost twenty different methods, Avogadro's number is usually determined by measuring a property of a particle unit and then comparing the same property being measured level macroscopic mole. Some researchers have sought by various means to determine the constant, k is the gas constant for a single molecule. The molar gas constant R divided by Avogadro's number k is obtained. Some of the best known for measuring the Avogadro number of methods are:

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