Question

the volume of 0.7g of a volatile compound at stp is 140ml. Find its molecular mass​

Answer 1

Explanation:

We can use the Ideal Gas Law to solve this problem

PV=nRT

Since n=

M

m

, we can rearrange this equation to get

PV=(

M

m

)RT

And we can solve this equation to get

M=

PV

mRT

STP is defined as 1 bar and 0 °C.

In this problem,

m=0.2 g

R=0.083 14 bar⋅L⋅K

−1

mol

−1

T=273.15 K

p=1 bar

V=56 mL=0.056 L

∴ M=

1 bar×0.056 L

0.2 g×0.08314 bar⋅L⋅K

−1

mol

−1

×273.15K

=80 g/mol

∴ The molar mass of the compound is 80 g/mol, so the molecular mass is 80 u.

Note: The answer can have only one significant figure, because that is all you gave for the mass of the compound.

OK

.

..

tq

Answer 2

Answer:

one volume of hydrogen should combine with one volume off chlorine to produce one volume the idea of compound atom was discarded and vapour density of gas =(molecular mass )/2