Question

.30 g of a volatile liquid displaces 90 cm^3 of air at STP in the victor mayer method the molecular mass of the liquid

Answer 1

Answer:

We can use the Ideal Gas Law to solve this problem:.

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

∣

∣

a

a

p

V

=

n

R

T

a

a

∣

∣

−−−−−−−−−−−−−−−

Since

n

=

m

M

, we can rearrange this equation to get

p

V

=

(

m

M

)

R

T

And we can solve this equation to get

M

=

m

R

T

p

V

STP is defined as 1 bar and 0 °C.

In your 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

=

0.2 g

×

0.083 14

bar⋅L⋅K

-1

mol

-1

×

273.15

K

1

bar

×

0.056

L

=

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.