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Question: One gm equivalent of a substance is present in: (A)- 0.25 mole of \[{{O}_{2}}\] (B)- 0.5 mole o...

One gm equivalent of a substance is present in:
(A)- 0.25 mole of O2{{O}_{2}}
(B)- 0.5 mole of O2{{O}_{2}}
(C)- 1.00 mole of O2{{O}_{2}}
(D)- 8.00 mole of O2{{O}_{2}}

Explanation

Solution

In this, we will find the value of one gram equivalent of oxygen. Then, we can calculate the amount of mole representing the one gram equivalent of oxygen.

Complete Solution :
-First, we will define the equivalent weight. It is also known as gram equivalent i.e. the mass of a given substance which will combine with or displace a fixed quantity.

-Now, we can write the formula of
Equivalent weight=Molecular weight (MW)n\text{Equivalent weight}=\dfrac{\text{Molecular weight (MW)}}{n}

here MW is the molecular weight of substance:
and n is the valency factor
-Molecular mass or molecular weight can be calculated from the summation of the atomic masses of each nuclide present in the molecule.
-n-factor is the number of electrons gained or lost by one atom of a compound. The n-factor for acid is the number of H+{{H}^{+}} ions replaced by 1 mole of acid in a reaction. The n-factor for a base is the number of OH−O{{H}^{-}} ions replaced by 1 mole of the base in a reaction. n-factor is not equal to the acidity.

- Now in the question the mass of the entity is given in terms of gm.
-Therefore, the gram equivalent will be calculated by multiplying the given moles into the MW.

-In this question, the molecular weight of O2=32g{{O}_{2}}=32g
-If we calculate the gram equivalent of O2{{O}_{2}}, it is equal to 8 gm mass.
-For the first option, 0.25 mole of O2=0.25×32=324=8gm{{O}_{2}}=0.25\times 32=\dfrac{32}{4}=8gm mass
-Second option, 0.5 moles of O2=0.5×32=322=16gm{{O}_{2}}=0.5\times 32=\dfrac{32}{2}=16gm mass
-Third option, 1.00 mole of O2=1×32=321=32gm{{O}_{2}}=1\times 32=\dfrac{32}{1}=32gm mass
-Fourth option, 8.00 mole of O2=8×32=256gm{{O}_{2}}=8\times 32=256gm mass.
-By calculating the given options, 8 gm mass is represented by 0.25 mole of O2{{O}_{2}} .
So, the correct answer is “Option A”.

Note: Don’t get confused between the terms equivalent weight, and gram equivalent. These both are the same terms. Remember the formula to calculate the equivalent weight. The molecular weight of oxygen must be known to you.