F5 Chem Molar Volume

2012-03-01 5:17 am

1) A gaseous mixture consists of methane and ethane in a mole ratio of 1:1. It has a volume of 200cm^3 at room temperature and pressure. What is the volume of oxygen required, measured at room temperature and pressure, for the complete combustion of the mixture?

2)An oxide of metal M reacts completely with carbon to give 12.6g of metal M and 2.38dm^3 of carbon dioxide measured at room temperature and pressure. What is the empirical formula of the oxide? ( relative atomic mass of M = 63.5)

Thank you very much.

回答 (1)

賣女孩的火柴

2012-03-01 11:41 pm

✔ 最佳答案

1.
In the mixture :
Volume of CH4 = Volume of C2H6 = 200 x (1/2) =100 cm³

CH4(g) + 2O2(g) → CO2(g) + 2H2O(l)
Volume of CH4 = 200 x (1/2) = 100 cm³
Volume of O2 required = 100 x 2 = 200 cm³

2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(l)
Volume of C2H6 = 200 x (1/2) = 100 cm³
Volume of O2 required = 100 x (7/2) = 350 cm³

Total volume of O2 required = 200 + 350 = 550 cm³

2.
No. of moles of CO2 formed = 2.38/24 mol
No. of moles of O in the CO2 formed = (2.38/24) x 2 = 2.38/12 mol
No. of moles of O in the oxide = No. of moles of O atoms in CO2formed = 2.38/12

Mole ratio M : O = 12.6/63.5 : 2.38/12 = 0.198 : 0.198 = 1 : 1

Hence, empirical formula = MO

參考: 賣女孩的火柴

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