What is the difference between formula unit mass and molecular mass and please explain mole concept .
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Solution
Formula Unit Mass :-
The formula mass (formula weight) of a molecule is the sum of the atomic weights of the atoms in its empirical formula.
The empirical formula is also known as the simplest formula. It is used to indicate the mole ratio of elements present in a compound. The empirical formula of glucose would be CH2O.
The molecular formula indicates the type and number of atoms in a molecule. The molecular formula of glucose is C6H12O6, which indicates that one molecule of glucosecontains 6 atoms of carbon, 12 atoms of hydrogen, and 6 atoms of oxygen.
The MOLE CONCEPT
The identity of a substance is defined not only by the types of atoms or ions it contains, but by the quantity of each type of atom or ion. For example, water, H2O, and hydrogen peroxide, H2O2, are alike in that their respective molecules are composed of hydrogen and oxygen atoms.
A mole is defined as the amount of substance containing the same number of discrete entities (such as atoms, molecules, and ions) as the number of atoms in a sample of pure 12C weighing exactly 12 g.
The number of entities composing a mole has been experimentally determined to be 6.02214179 × 1023, a fundamental constant named Avogadro’s number (NA) or the Avogadro constant in honor of Italian scientist Amedeo Avogadro. This constant is properly reported with an explicit unit of “per mole,” a conveniently rounded version being 6.022 × 1023/mol.
Consistent with its definition as an amount unit, 1 mole of any element contains the same number of atoms as 1 mole of any other element. The masses of 1 mole of different elements, however, are different, since the masses of the individual atoms are drastically different.