Question

A mixture of 1.65*10 21 molecules of X and 1.85*10 21 molecules of Y weighs 0.688 g. The mol.wt. of X (assume mol.wt.of Y is 187)?

Answer 1

Answer : The molecular weight of X is, 41.588 grams

Solution : Given,

Number of molecules of X = $1.65\times 10^{21}$

Number of molecules of Y = $1.85\times 10^{21}$

Molecular weight of Y = 187 g/mole

Total mass of mixture = 0.688 g

Formula used :

$\text{Mass of mixture}=[\frac{\text{Number of molecules of X}}{\text{Avogadro's number}}\times \text{Molar mass of X}]+[\frac{\text{Number of molecules of Y}}{\text{Avogadro's number}}\times \text{Molar mass of Y}]$

Now put all the given values in this formula, we get the molecular mass of X.

$0.688g=[\frac{1.65\times 10^{21}}{6.022\times 10^{23}}\times \text{Molar mass of X}]+[\frac{1.85\times 10^{21}}{6.022\times 10^{23}}\times 187g/mole]$

$\text{Molar mass of X}=41.588g$

Therefore, the molecular weight of X is, 41.588 grams

Answer 2

Answer:

Explanation:

Answer : The molecular weight of X is, 41.588 grams

Solution : Given,

Number of molecules of X =  

Number of molecules of Y =  

Molecular weight of Y = 187 g/mole

Total mass of mixture = 0.688 g

Formula used :

Now put all the given values in this formula, we get the molecular mass of X.

Therefore, the molecular weight of X is, 41.588 grams