Calculate the density, in grams per liter, of a gas at STP if 4.90 L of the gas at 26.3 °C and 701.5 mm Hg weighs 0.316 g.?
回答 (3)
from the ideal gas law
.. PV = nRT
from the definition of moles
.. n = mass / mw.... .(mw is my abbrev for molecular weight.. molar mass.. etc)
subbing
.. PV = (mass / mw) RT
rearranging
.. mw x P = (mass / V) x RT
and since density = mass / volume... let's use ρ to represent density
.. mw x P = ρ x R x T
so that for 2 cases
.. mw x P1 = ρ1 x R x T1
.. mw x P2 = ρ2 x R x T2
dividing
.. (P1 / P2) = (ρ1 / ρ2) x (T1 / T2)
rearranging
.. ρ2 = ρ1 x (T1 / T2) x (P2 / P1)
solving
.. ρ2 = (0.316 g / 4.90 L) x (299.45K / 273.15K) x (760mmHg / 701.5mmHg) = 0.0766 g/L
Mass = 0.316 g
Volume = 4.90 L
Density of the gas
= Mass / Volume
= (0.316 g) / (4.90 L)
= 0.0645 g/L
n = PV / RT = (701.5 mmHg) x (4.90 L) / ((62.36367 L mmHg/K mol) x (26.3 + 272.15) K) = 0.1847 mol
(22.414 L/mol) x (0.1847 mol) = 4.1399 L at STP
(0.316 g) / (4.1399 L) = 0.0763 g/L
收錄日期: 2021-04-18 14:47:24
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20160428191939AAsEzZl
檢視 Wayback Machine 備份