Question

Calculate the weight of a substance X which in gaseous form occupies 10 litres at 27°C and 700mm pressure. The molecular weight of X is 60.​

Answer 1

Given :-

Initially :

• P1 = 700mm
• T1=27°C + 273 = 300K
• V1 =10 litres

Finally(stp) :

• P2 = 760mm
• T2 = 273k

To Find :-

• V2 = ????

Using the gas equation that is,

=> P1V1 = P2V2

=> 700×10/300 = 760×V2/273

=> 273×70=760×V2×3

=> 19110 = 2280×V2

=> 19110/2280= V2

=> 8.38 litres = V2

Therefore:-

60g of gas X occupies 22.4litres at STP

? g of gas occupies 8.38litres

So:-

=> 22.4 litres =60g

=> 1 litre = 60/22.4g

=> 8.38litres =8.38×60/22.4g =22.45g

Hence:-

• V2 = 8.38 litres and
• Weight of substance X is 22.45g.