I need help in Chemistry?

if you recall

PV = nRT

V/n = RT/P = (0.08206 Latm/molK) x (273.15) / (1atm) = 22.4 L/mol @STP

let me repeat that..

the volume of 1 mole of an ideal gas = 22.41 L at STP

then..

*** 1 ***

2.50g SO3 x (1 mole SO3 / 80.07g SO3) x (22.41 L / mole) = 0.700 L

and

2.50g / 0.700L = 3.57 g/L

*** 2 ***

2.8x10^22 molecules CO2 x (1 mole CO2 / 6.022x10^23 moelcules CO2) = __ mole CO2

__ mole CO2 x (44.02g CO2 / mole CO2) = __ g CO2

__ molecules CO2 x (1 atom C / 1 molecule CO2) = __ atoms C

__ molecules CO2 x (2 atoms O / 1 molecule CO2) = __ atoms O

__ mole CO2 x (22.41L / mol) = __ L

density = __g / __L

*** 3 ***

250mL F2 x (1L / 1000mL) x (1 mole / 22.41L) = __ mol F2

__ mol F2 x (38.0 g F2 / mole F2) = __g F2

__ mol F2 x (6.022x10^23 molecules F2 / mol F2) = __ molecules F2

__ molecules F2 x (2 atoms F / 1 molecule F2) = __ atoms F

density = __g F2 / 0.250L F2 = __ g/L

********

I leave the rest to you.

1) 2.5 g/80g = .03125 moles

PV=nRt

V = nRt/p

V = (.0821 atm x L/ moles K)(.03125 moles)(273.15 K ) / (1atm)

V = __ Liters

D = mass/volume

D = kilograms / m^3

2) 2.8 x10^22 molecules / 6.02 * 10^23 (which is Avogadro's #) = moles

moles x molar mass = mass

to find carbon and oxygen you must do the partial pressure thingy and that will give you your number

V and density find it the same way using PV = nRt

3) n = Rt/PV

n = moles then multiply by molar mass to get your mass...

molecules multiply by avogadro's number,

flourine atoms you have to do the weird partial pressure thingy again

and D = m/v

do the work on your own, this should help you though.