Question

The chloride of metal contains 71%cl by weight and the vapour density of it is 50 .the atomic weight of the metal will be

Answer 1

Vapor density describes the mathematical relationship between the density of vapor to the density of hydrogen.

It is calculated as follows: 

                    Vapor density = Molar mass of the gas/molar mass of hydrogen.

- From the formula above you can calculate the molar mass of the gas as follows:

   molar mass of gas = molar mass of Hydrogen(= 2 ) × Vapor density of gas

The molar mass of this chloride metal = 2 x 50
                                                             =  100

Find mass of this metal in 100 g of its chloride: 
 
In the metal chloride 71% is chlorine
Then, that means 29% mass is the metal

In 100g of this metal the mass of the metal = 29/100 × 100g = 29g

Find the moles of chlorine: 

moles = mass / molar mass
           = 71/35.5
           = 2
   
Let the empirical formula of the metal chloride be:

XCl₂  

compute empirical formula weight = x (molar mass × moles = mass)+(35.2 × 2) 

29  + 71 ( divide by molar mass to find formula ratio)

29+ 71/100 = 100/100

formula ratio = 1

Therefore the formula of the metal chloride is XCl₂

The mole of the of the metal from its 100g of its chloride from the formula = 1

What we got:

molar mass x moles = mass
                                    
molar mass = mass/moles
                     = 29/1

therefore molar mass = 29

The atomic weight of the metal = 29