Question

What is the molecular weight (weight of a mol of gas) for a gas when 250.0 ml of the gas at 707 torr and 28.0 degrees C weigh 1.250 grams?

Answer 1

PV=NRT
P = pressure (ATM)
V = volume (Liters)
N = moles
R = Gas constant
T = Temperature (Kelvins)

Answer 2

You will need to convert to appropriate units and solve for mole.
Molecular weight is = mole/grams
So once you have the moles you know the grams and can do the division.

Answer 3

0.007529 g/mol ?

Answer 4

hmm its too small
you made mistake somewhere

Answer 5

PV= nRT
P= 707 torr - convert to atm by multiplying the value by 0.001316
V= 250 mL - convert to L by dividing the value by 1000
n= Unknown mole
R= constant value 0.08206 (you can use this value if you are taking pressure in atm and volume in L)
T= 28 Celsius - convert to Kelvin by adding 273 to Celsius value

now you are ready to use the formula

make n as a subject
PV=nRT
n= PV/RT
now put the value into this formula and get the answer for moles

now you got moles
so we can use formula
mole= mass/Molecular mass
the question is asking for molecular mass so lets make it as a subject
thus we get this

Molecular mass= mass/mole

mass= 1.250 g
mole= you just found it
so now put the values into the formula
and get final answer
Hope it helps :)

Answer 6

Molecular weight is g/mol, not mol/g.

Answer 7

uh i thought i made this mistake @JFraser lol