Chemical Forums

Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Xhevin on March 26, 2020, 07:34:44 AM

Title: The combustion reactions of ethene and ethin
Post by: Xhevin on March 26, 2020, 07:34:44 AM: The combustion reactions of ethene and ethin are given:
C2H4 + 302 = 2CO2 +2 H20
H= -6787Kj

2 C2H2 +5 02 = 4CO2 +2 H20
H= -2599 Kj

Find how much mole of ethene and ethin the mixture with mass= 218gram has If from combustion of this mixture were released 10955.5 Kj.

I have a test and this is the only problem I can not understand because my teacher hasn't explained (coronavirus). Sorry for the bad translation. Thanks in advance.
Title: Re: The combustion reactions of ethene and ethin
Post by: Babcock_Hall on March 26, 2020, 07:54:43 AM: It is a forum rule that you must show your attempt before we can help you. Perhaps you could start by writing an equation involving the masses of ethene and ethyne.
Title: Re: The combustion reactions of ethene and ethin
Post by: Xhevin on March 26, 2020, 08:33:50 AM: Quote from: Babcock_Hall on March 26, 2020, 07:54:43 AM
It is a forum rule that you must show your attempt before we can help you. Perhaps you could start by writing an equation involving the masses of ethene and ethyne.
I think I solved it But i am not sure. I got n¹=6.4 mole and n²=1.46
Title: Re: The combustion reactions of ethene and ethin
Post by: AWK on March 26, 2020, 08:39:58 AM: It's easy to check.
Title: Re: The combustion reactions of ethene and ethin
Post by: Xhevin on March 26, 2020, 08:47:19 AM: Quote from: AWK on March 26, 2020, 08:39:58 AM
It's easy to check.
How can I do that
Title: Re: The combustion reactions of ethene and ethin
Post by: Xhevin on March 26, 2020, 08:49:10 AM: Quote from: AWK on March 26, 2020, 08:39:58 AM
It's easy to check.
I am wrong again. Been here for the past 3 hours lol
Title: Re: The combustion reactions of ethene and ethin
Post by: AWK on March 26, 2020, 08:56:11 AM: Look at the numbers. 218/26 (acetylene) ~ 8.5.
This amount during combustion gives more than 10,000 KJ.
This means you have about 8 moles of C2H2 and nearly traces of C2H4.
Title: Re: The combustion reactions of ethene and ethin
Post by: Xhevin on March 26, 2020, 09:10:02 AM: Quote from: AWK on March 26, 2020, 08:56:11 AM
Look at the numbers. 218/26 (acetylene) ~ 8.5.
This amount during combustion gives more than 10,000 KJ.
This means you have about 8 moles of C2H2 and nearly traces of C2H4.
Why 26? There is 2C2H2 so it should be 52.
Title: Re: The combustion reactions of ethene and ethin
Post by: AWK on March 26, 2020, 09:22:43 AM: 2·26=52
Title: Re: The combustion reactions of ethene and ethin
Post by: MNIO on March 26, 2020, 12:48:30 PM: how did you calculate the moles of ethene and ethyne... (note the spelling)?
Title: Re: The combustion reactions of ethene and ethin
Post by: Enthalpy on March 27, 2020, 05:52:59 AM: Quote from: Xhevin on March 26, 2020, 07:34:44 AM
C₂H₄ + 3 0₂ :rarrow: 2 CO₂ + 2 H₂0 ΔH= -6787 kJ

2 C₂H₂ + 5 0₂ :rarrow: 4 CO₂ + 2 H₂0 ΔH= -2599 kJ

I can't believe two acetylenes produce less heat than one ethylene. Check the figures.
Title: Re: The combustion reactions of ethene and ethin
Post by: AWK on March 27, 2020, 07:36:18 AM: The heat of combustion of acetylene (for 2 moles) is correct. This heat of ethylene combustion is wrong.
Title: Re: The combustion reactions of ethene and ethin
Post by: Fish200398 on March 29, 2020, 02:21:31 PM: A = mole of ethylene
B = mole of ethyne

A(6787Kj) + B(2599) = 10955.5Kj
A(28) + B(52) = 218 g
Title: Re: The combustion reactions of ethene and ethin
Post by: AWK on March 29, 2020, 02:49:23 PM: The heat of combustion of 1 mol ethylene is 1411 kJ/mol
The molecular mass of acetylene is 26
Title: Re: The combustion reactions of ethene and ethin
Post by: Fish200398 on April 02, 2020, 06:05:44 AM: Ok sir. Even hough 2C2H2 still 26 g/mol
Title: Re: The combustion reactions of ethene and ethin
Post by: AWK on April 02, 2020, 06:10:34 AM: Quote from: Helly on April 02, 2020, 06:05:44 AM
Ok sir. Even hough 2C2H2 still 26 g/mol
The question is:
Quote
Find how much mole of ethene and ethin the mixture