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CLASS 39 3 º B-3 º A: SOLVING EXERCISES -

Hello everyone.

The 3 B Wednesday and Friday at 3 º A \u200b\u200btype problems we test. These exercises will be the style of the exam.

Consider these items:

molecular mass ( M ) of a substance is the sum of atomic weights all atomic mass units . For example, the molecular weight of water, H 2 O, is 18.0 amu.

atoms in a molecule of the substance and is expressed in the

molar mass (M) of a substance is the mass of one mole of substance . Carbon-12 has, by definition, a molar mass of exactly 12 g / mol. For all substances, the mass

molar in grams per mole is numerically equal to the molecular mass in mass units atomic

.

cocept mole (n)

Before talking about this concept, we will discuss a concept known to everyone.

Imagine a dozen eggs.

dozen

When we talk about, talk about a concept that is referred to to a known quantity. 12

1 / 2 dozen apples = 6 blocks

The same applies to the concept of MOL.

mol When we talk, we refer to an amount, but not eggs or apples, but that of atoms, molecules, ions, etc.

This amount is:

6.02 X 10 23 602,000. 000,000. 000,000. 000,000 mol.

Uses of this concept:

For example, to know how many moles there are of an atom or molecule. To determine this we need to know how many grams are of the atom or molecule, and what atomic or molecular weight. using the following equation:

mol = grams of the atom or molecule / atomic weight or molecular weight

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