Gram Atomic Mass,Gram Formula Mass,Gram Molecular Mass

Gram Atomic Mass

Gram atomic mass is the term used to describe an element’s atomic weight when stated in grams. An element’s molar mass is defined as the mass of one mole in grams.

Gram Atomic Mass Example

Helium, for instance, has a gram atomic mass of 4 g . Similarly sodium (Na), has a gram atomic mass of 22.99 grams and an atomic weight of 22.99 u. A mole of sodium thus weighs 22.99 g of atoms.

Gram Formula Mass

Formula mass of an ionic compound expressed in grams is called gram formula mass

Gram Formula Mass Example

 It can be explained with the help of the following example

NaCl Formula Mass

Formula mass of NaCl = 23 + 35.5

 = 58.5amu

Therefore, gram formula mass of NaCl = 58.5g = mole of NaCl formula units.

KCl Formula Mass

 Formula mass of KCl = 39 + 35.5

 = 74.5amu. So, gram formula mass of KCl = 74.5g

Gram Molecular Mass

 The mass in gram of one mole of a molecule is known as the gram molecular mass. Molar mass and gram molecular mass are equivalent. The sole distinction is that the mass unit to be utilized is specified by gram molecular mass. The mass of a molecule can be expressed in either grams or grams per mole (g/mol).

Gram Molecular Mass Examples

Molecular mass of H₂O = 2 x 1.008 + 16 = 18.016 amu

So, gram molecular mass of H2O = 18.016 g

Molecular mass of C₆H₁₂O₆ = 6 x 12 + 12 x 1.008 + 16 x 6 = 180.096 amu

So, gram molecular mass of C₆H₁₂O₆ = 180.096 g.

Differentiate between gram atomic mass, gram molecular mass, and gram formula mass.

ANSWER

Statements

1. In contrast to gram formula mass, which represents one mole of ionic formula units of a compound, gram atomic mass denotes one mole of atoms of an element. Gram molecular mass denotes one mole of molecules of a compound or an element that exists in a molecular state.
2. The gram atomic mass contains 6.022 x 10²³ atoms, gram molecular mass contains 6.022 x 10²³ molecules whereas gram formula mass contains 6.022 x 10²³ formula units
3. Therefore one mole can be defined as formula mass, atomic mass, or molecular mass expressed in grams.

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