Question

which mass of O₂ molecule will contain the same number of molecules as 2.5 moles of Cl₂. Options are - 180gm or 100gm or 71 gm or 80 gm.
KINDLY EXPLAIN WITH FORMULAE

Answer 1

2.5 moles of O2 contains same number of molecules as 2.5 moles of Cl2.Because number of molecules is only dependent on moles.
i.e. 2.5×32 = 80 gm of O2

Answer 2

80 g of O₂ molecule will contain the same number of molecules as 2.5 moles of Cl₂.

Given,

Moles of chlorine(Cl₂) = 2.5

Molecule given = O₂ molecule

To find,

the mass of O₂ molecule that contain the same number of molecules as 2.5 moles of Cl₂.

Solution:

Moles of O₂ = $\frac{x}{32}$                   (Molar mass of O₂ = 32 g)

Number of molecules in 1 mole Cl₂ = NA(Avogadro's number)

(NA = $6.022X10^{23\\}$)

Number of molecules in 2.5 mole Cl₂ = 2.5 NA

Number of moles = Given number of molecules/Avogadro's number

Number of moles = Given mass/Molar mass

$\frac{2.5 NA}{NA} = \frac{x}{32}$

$x = 2.5X32$

$x=80.$

80 g of O₂ molecule will contain the same number of molecules as 2.5 moles of Cl₂.

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