Question

One g equivalent of a substance is present in-
1) 0.25 mole of O2
2)0.5 mole of O2
3)1.00 mole of O2
4)8.00 mole of O2

Answer 1

Answer: The correct answer is Option 1.

Explanation:

To calculate the equivalent weight of a substance, we use the equation:

$\text{Equivalent weight}=\frac{\text{Molecular mass of the substance}}{\text{Valency}}$

Molecular mass of oxygen molecule = 32

Valency of oxygen molecule = 4

Putting values in above equation, we get:

$\text{Equivalent weight of oxygen molecule}=\frac{32}{4}=8g/eq.$

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$   ....(1)

And, to calculate the number of gram equivalents, we use the equation:

$\text{Number of gram equivalents}=\frac{\text{Given mass}}{\text{Equivalent weight}}$     .....(2)

For the given options:

• Option 1:  0.25 mole of $O_2$

Moles of $O_2$ = 0.25 mol

Molar mass of $O_2$ = 32 g/mol

Putting values in equation 1, we get:

$0.25mol=\frac{\text{Mass of }O_2}{32g/mol}\\\\\text{Mass of }O_2=8g$

Now, using equation 2, we get:

Equivalent weight of $O_2$ = 8 g/eq

Given mass of $O_2$ = 8 g

Putting values in equation 2, we get:

$\text{Gram equivalents of }O_2=\frac{8g}{8g/eq.}=1eq.$

• Option 2:  0.5 mole of $O_2$

Moles of $O_2$ = 0.5 mol

Molar mass of $O_2$ = 32 g/mol

Putting values in equation 1, we get:

$0.5mol=\frac{\text{Mass of }O_2}{32g/mol}\\\\\text{Mass of }O_2=16g$

Now, using equation 2, we get:

Equivalent weight of $O_2$ = 8 g/eq

Given mass of $O_2$ = 16 g

Putting values in equation 2, we get:

$\text{Gram equivalents of }O_2=\frac{16g}{8g/eq.}=2eq.$

• Option 3:  1.00 mole of $O_2$

Moles of $O_2$ = 1.00 mol

Molar mass of $O_2$ = 32 g/mol

Putting values in equation 1, we get:

$1.00mol=\frac{\text{Mass of }O_2}{32g/mol}\\\\\text{Mass of }O_2=32g$

Now, using equation 2, we get:

Equivalent weight of $O_2$ = 8 g/eq

Given mass of $O_2$ = 32 g

Putting values in equation 2, we get:

$\text{Gram equivalents of }O_2=\frac{32g}{8g/eq.}=4eq.$

• Option 4:  8.00 mole of $O_2$

Moles of $O_2$ = 8.00 mol

Molar mass of $O_2$ = 32 g/mol

Putting values in equation 1, we get:

$8.00mol=\frac{\text{Mass of }O_2}{32g/mol}\\\\\text{Mass of }O_2=256g$

Now, using equation 2, we get:

Equivalent weight of $O_2$ = 8 g/eq

Given mass of $O_2$ = 256 g

Putting values in equation 2, we get:

$\text{Gram equivalents of }O_2=\frac{256g}{8g/eq.}=32eq.$

Hence, the correct answer is Option 1.