[Xhevin]

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.

[Babcock_Hall]

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.

[Xhevin]

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

[AWK]

It's easy to check.

[Xhevin]

It's easy to check.

How can I do that

[Xhevin]

It's easy to check.

I am wrong again. Been here for the past 3 hours lol

[AWK]

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.

[Xhevin]

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.

[AWK]

2·26=52

[MNIO]

how did you calculate the moles of ethene and ethyne... (note the spelling)?

[Enthalpy]

C₂H₄ + 3 0₂  2 CO₂ + 2 H₂0  ΔH= -6787 kJ

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

I can't believe two acetylenes produce less heat than one ethylene. Check the figures.

[AWK]

The heat of combustion of acetylene (for 2 moles) is correct. This heat of ethylene combustion is wrong.

[Fish200398]

A = mole of ethylene
B = mole of ethyne

A(6787Kj) + B(2599) = 10955.5Kj
A(28) + B(52) = 218 g

[AWK]

The heat of combustion of 1 mol ethylene is 1411 kJ/mol
The molecular mass of acetylene is 26

[Fish200398]

Ok sir. Even hough 2C2H2 still 26 g/mol