Gram Atomic Mass

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A unified atomic mass unit (u) also known as dalton (Da) is the non-system unit of mass that is used for indicating mass in atoms and molecules. It is defined as one-twelfth of the mass of a neutral atom of carbon-12 in its ground state. 1 Da ≈ 1.6605310⁻²⁷ kg. The gram atomic mass of an element is atomic mass expressed in grams (GAM). The gram atomic mass of chlorine is 35.5 g. Thus one gram hydrogen atom means 1.008 g of hydrogen. One gram atom of carbon means 12 g of carbon. 2 gram atom of chlorine means 2 × 35.5 = 71 g of chlorine. Jul 03, 2019 Gram molecular mass is the mass in grams of one mole of a molecular substance. Gram molecular mass is the same as molar mass. The only difference is that gram molecular mass specifies the mass unit to be used. Gram molecular mass may be reported in grams or grams per mole (g/mol). Atomic mass units u to gram g unit converter of weight Enter value and select a unit of weight measurement to perform the conversions. Value: From: a.u. Of mass atomic mass unit carat centner grain gram kilogram long ton microgram milligram nanogram ounce pennyweight picogram pound short ton slug stone tonne troy ounce troy pound.

Class 11 Gram atomic mass

Gram Atomic Mass Of Sodium

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Gram Atomic Mass

Atomic mass expressed in grams is termed as Gram Atomic Mass. We shall observe later that this is the mass of one mole of the atoms. Gram atomic mass is the weight of 1 gram atom of the element.
For example, Atomic mass sodium is 23 amu therefore, 1 gram atom of sodium weighs 23g. Its gram atomic mass is 23 grams.
Mass of 1 atom of sodium is, grams =gms. Do not confuse it with gram atomic mass.
Gram molecular mass
Molecular mass expressed in grams is termed as Gram
Molecular Mass. We shall observe later that this is the mass of one mole of the molecules.
For example, One gram molecule of water will have a weight equal to 18 grams which is its gram molecular mass.
Formula mass: For substances which are ionic the formula does not represent a molecule (molecules are formed only with covalent bond) the mass based on the formula would be called as formula mass and not molecular mass.
For example, The formula mass of NaCl is 23+35.5=58.5
MOLE CONCEPT
One mole is an amount of substance containing Avogadro’s number of particles. Avogadro’s number is equal to 602,214,199,000,000,000,000,000 or more simply, 6.02214199 × 1023.
Some people think that Amedeo Avogadro (1776-1856) determined the number of particles in a mole and that is why the quantity is known as Avogadro number. In reality, Avogadro built a theoretical foundation for determining accurate atomic and molecular masses. The concept of a mole did not even exist in Avogadro’s time.
Much of Avogadro’s work was based on that of Joseph-Louis Gay-Lussac (1778-1850).Gay-Lussac developed the law of combining volumes that states: “In any chemical reaction involving gaseous substances the volumes of the various gases reacting or produced are in the ratios of small whole numbers”. (Masterton and Slowinski, 1977) Avogadro reinterpreted Gay-Lussac’s findings and proposed in 1811 that (1) some molecules were diatomic and (2) “equal volumes of all gases at the same temperature contain the same number of molecules”. The second proposal is what we refer to as Avogadro’s hypothesis.
The hypothesis provided a simple method of determining relative molecular weights because equal volumes of two different gases at the same temperature and pressure contained the same number of particles, so the ratio of the masses of the gas samples must also be that of their particle masses. Unfortunately, Avogadro’s hypothesis was largely ignored until Stanislao Cannizzaro (1826-1910) advocated using it to calculate relative atomic masses or atomic weights. Soon after the International Chemical Congress Karlsrule in 1860, Cannizzaro’s proposal was accepted and a scale of atomic weights was established.
To understand how Avogadro’s hypothesis can be used to determine relative atomic and molecular masses, visualize two identical boxes with oranges in one and grapes in the other. The exact number of fruit in each box is not known, but you believe that there are equal numbers of fruit in each box (Avogadro’s hypothesis). After subtracting the masses of the boxes, you have the masses of each fruit sample and can determine the mass ratio between the oranges and the grapes. By assuming that there are equal numbers of fruits in each box, you then know the average mass ratio between a grape and an orange, so in effect, you have calculated their relative masses (atomic masses). If you chose either the grape or orange as a standard, you could eventually determine a scale of relative masses for all fruit.

How big is a Mole?
One mole of marbles would cover the entire Earth (oceans included) for a depth of three miles.
One mole of $100 bills stacked one on top of another would reach from the Sun to Pluto and back 7.5 million times.
It would take light 9500 years to travel from the bottom to the top of a stack of 1 mole of $ 1 bills.
A mole (symbol mol) is defined as the amount of substance that contains as many atoms, molecules, ions, electrons or any other elementary entities as three are carbon atoms in exactly 12 gm of 12C. The number of atoms in 12 g 12C is called Avogadro’s number (NA).

Methods of Calculations of Mole

Gram atomic mass

(a) Number of moles of molecules =

(b) Number of moles of atoms =

Gram Atomic Mass

DefineAtomic

(c) Number of moles of gases =

Define Gram Atomic Mass

(Standard molar volume at STP = 22.4 lit)

(d) Number of moles of particles e.g. atoms, molecules ions etc =

Gram Atomic Mass Unit

(e) For a compound, 1 mole of the compound will have x moles of A and Y moles of B.

If volume of gas is given along with its temperature (T) & pressure (P) then n =

Atomic

where R = .0821 lit-atm/mol K & P is in atmosphere & T in Kelvin.

Gram Atomic Mass Of Oxygen

Do not use the expression for solids/liquids for eg.H2O at.
STP or NTP conditions Standard conditions means that temperature is C or 273K and pressure is one atmosphere or 760mm of Hg.
1 gm -atom is same as 1 mole of an atom & hence will have wt. equal to atomic wt. expressed in gms.
1 gm-molecule is same as 1 mole of the atom & hence will have wt. equal to molecule wt. expressed in gms.
1 gm- Ion is same as 1 mole of an ion & hence will have wt. equal to ionic wt.
Now, can you differentiate between 1 gm – atom oxygen & 1gm-molecule oxygen.
Remember 1 gm of atom & 1 gm-atom are two different phases. Former is mentioning wt. (equal to 1 gm) & latter is mentioning moles. (indirectly wt. is equal to atomic wt in gms).
e.g.
(1) “x g atom of nitrogen” = x moles of N atom
X × NA= number of N atoms.
(2) “x g molecular of nitrogen” = x moles of molecules
=X × NA molecules of N2= 2×NA number of N atom
(3) “x g moles of nitrogen is an ambiguous statement “ It will be completed as x g moles of nitrogen atom or, x g moles of nitrogen molecule.

Gram Atomic Mass Definition

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