Question

what is the molar mass of gas if 0.495 g of sample occupies 127 ml at 754 torr pressure and 98° C temperature
a) 120
b)160
c)190
d)200
pls give a proper explanation ​

Answer 1

Answer:

Explanation:

First calculate the moles of the gas using the gas law,

P

V

=

n

R

T

, where

n

is the moles and

R

is the gas constant. Then divide the given mass by the number of moles to get molar mass.

Calculate Moles

Given/Known

mass

:

0.950 g

pressure

:

P

=

0.985 atm

volume

:

V

=

232

mL

×

1

L

1000

mL

=

0.232 L

gas constant

:

R

=

0.082057338 L atm K

−

1

mol

−

1

temperature

:

T

=

95

o

C

+

273.15

=

368 K

Unknown

n

Equation

P

V

=

n

R

T

Solution

Rearrange the equation to isolate

n

and solve.

n

=

P

V

R

T

n

=

0.985

atm

×

0.232

L

0.082057338

L

atm

K

−

1

mol

−

1

×

368

K

=

0.007568 mol

(I'm keeping a couple of guard digits to reduce rounding errors. I'll round to three significant figures at the end.)

Molar Mass of Gas

Molar mass

=

grams

mol

Molar mass

=

0.950

g

0.007568

mol

=

126 g/mol