Question

На сгорание образца метана объемом 7 литров,содержащего негорючие газообразные примеси,израсходовано 60 литров воздуха с объемной долей кислорода 21%.Определите объемную долю метана в исходном образце.

Answer 1

1.Определим количество кислорода в воздухе:
60лх21%=12,6л
2. Пишем уравнение реакции  и ставим вверху количества веществ по реакции согласно уравнению, внизу- имеющееся количество кислорода и необходимого метана (его примем за Х ):
22,4л   44,8л                                3. Находим Х из пропорции:
CH4 +  2O2  =  CO2 + H2O         Х=(22,4лх12,6л)/44,8л
Х         12,6л                              Х= 6,3л
4. На данное количество кислорода необходимо 6,3л метана, у нас 7л метана с примесями. Объемная доля чистого метана:
(6,3л/7,7л)х100%=90%

Answer 2

Calculation of Methane Volume in the Sample

To determine the volumetric fraction of methane in the initial sample, we need to calculate the volume of methane consumed during combustion.

Given: - Volume of the sample containing methane and non-combustible gaseous impurities: 7 liters - Volume of air consumed during combustion: 60 liters - Oxygen concentration in the air (volumetric fraction): 21%

To calculate the volume of methane consumed, we can use the stoichiometry of the combustion reaction between methane and oxygen:

CH4 + 2O2 → CO2 + 2H2O

From the balanced equation, we can see that for every 1 mole of methane consumed, 2 moles of oxygen are required. Therefore, the volume of methane consumed is directly proportional to the volume of oxygen consumed.

To find the volume of methane consumed, we can use the following proportion:

Volume of methane consumed / Volume of oxygen consumed = Volume of methane in the sample / Volume of oxygen in the air

Let's calculate the volume of methane consumed:

Volume of oxygen consumed = Volume of air consumed * Oxygen concentration = 60 liters * 0.21 = 12.6 liters

Using the proportion, we can calculate the volume of methane consumed:

Volume of methane consumed = (Volume of methane in the sample / Volume of oxygen in the air) * Volume of oxygen consumed = (7 liters / 12.6 liters) * 12.6 liters = 7 liters

Therefore, the volume of methane consumed during combustion is 7 liters.

To determine the volumetric fraction of methane in the initial sample, we can use the following formula:

Volumetric fraction of methane = Volume of methane consumed / Volume of the sample

Volumetric fraction of methane = 7 liters / 7 liters = 1

Therefore, the volumetric fraction of methane in the initial sample is 100%.

Please note that the calculation assumes complete combustion of methane and does not take into account any other gaseous impurities present in the sample.