How many grams of....?

Question

How many grams of silicon tetraflouride, a gas, at room temperature, would fill the same volume as that occupied by 350 grams of carbon monoxide at 75C and 575 torr?

Answer 1

The molecular mass of CO is 28, therefore 350 grams of CO is 350/28 = 12.5 moles.

From the gas law, PV = nRT, (n = no of moles) compute the volume. Then use this volume in the same equation, except solve for n; this gives you the no of moles of silicon tetrafluoride; look up the molecular mass of silicon tetrafluoride and multiply by this n to get the grams needed.

NOTE: R is the gas constant, and the value you should use is 62.36 Liter*Torr / (ºK*mole); if the first part is at one atmosphere of pressure (as well as at room temp) then use R=0.082 (Liter*atm / (ºK*mole) for the volume calculation. This will save you some trouble in unit conversions.

Room temp is usually taken as 298ºK (25ºC), but that is not an official standard. 75ºC is 348ºK

Answer 2

575 torr x (1 atm/760 torr) = 0.757 atm

75C + 273 = 348 K

350 g CO x (1 mol / 28 g) = 12.5 mol

V = nRT/P

V = (12.5 mol)(0.0821 L atm/mol K)(348 K)/(0.757 atm)

V = 472 L


Now let's assume that room temp = 298 K
Your problem didn't specify the pressure of the SiF4
I will assume 1 atm??

n = PV/RT

n = (1)(472)/(0.0821 x 298) = 19.3 moles

19.3 moles SiF4 x (104.1 g/mol) = 2009 grams

Hope that was somewhat helpful!

Answer 3

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Answer 4

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