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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: jamaicanman on February 21, 2011, 11:58:15 AM

Title: Volume of gas mixtures
Post by: jamaicanman on February 21, 2011, 11:58:15 AM

If 50cm cubed of ethyne are burned completely in 220 cm cubed of oxygen, what will be the volume and composition of the resulting gas mixture? All volumes are measured under the same conditions of temperature and pressure.

Title: Re: Volume of gas mixtures
Post by: DevaDevil on February 21, 2011, 12:18:48 PM

can you give us your approach?

start with the balanced equation

Title: Re: Volume of gas mixtures
Post by: jamaicanman on February 21, 2011, 12:21:05 PM

2C2H2 + 5O2 -> 4CO2 + 2H2O

Title: Re: Volume of gas mixtures
Post by: jamaicanman on February 21, 2011, 12:24:34 PM

Would I then find out whether ethyne or oxygen is in excess?

Title: Re: Volume of gas mixtures
Post by: DevaDevil on February 21, 2011, 12:33:48 PM

yes (also you KNOW oxygen has to be in excess, because they state that is is complete combustion; in incomplete combustion, oxygen is limiting and some CO gets formed)

good equation, so continue reasoning and I am sure you will get the answer :)
(also, since water is formed you will have to assume it is either liquid or gas, depending on the temperature/pressure you are in. In high-temp combustion I would assume water is present in gas-form)

Title: Re: Volume of gas mixtures
Post by: jamaicanman on February 21, 2011, 12:39:21 PM

So there is 95cm cubed O2 left and 100cm cubed of CO2?

Title: Re: Volume of gas mixtures
Post by: DevaDevil on February 21, 2011, 12:45:51 PM

yes and yes, do not forget the water (if it is in gas-form)
if it is in liquid you need to know the temp/pressure to determine the volume

Title: Re: Volume of gas mixtures
Post by: jamaicanman on February 21, 2011, 12:48:55 PM

I'm only asked for the gas mixture, and I'm not given a temperature. Should I take the water as a liquid or a gas?

Title: Re: Volume of gas mixtures
Post by: DevaDevil on February 21, 2011, 12:56:01 PM

I would assume a gas at combustion-temperatures, but that is up to you and your teacher to make clear

Title: Re: Volume of gas mixtures
Post by: jamaicanman on February 21, 2011, 12:57:17 PM

Thanks very much

Title: Re: Volume of gas mixtures
Post by: AWK on February 28, 2011, 07:38:19 AM

Quote from: jamaicanman on February 21, 2011, 11:58:15 AM

If 50cm cubed of ethyne are burned completely in 220 cm cubed of oxygen, what will be the volume and composition of the resulting gas mixture? All volumes are measured under the same conditions of temperature and pressure.

Should be also stated that all water is removed.