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Topic: Enthalpy help please!!!!  (Read 6324 times)

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Offline I have questions

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Enthalpy help please!!!!
« on: February 24, 2013, 09:10:54 PM »
Consider the following reaction.
CH3OH(g) → CO(g) + 2 H2(g) ΔH = +90.7 kJ

(a) Is the reaction exothermic or endothermic?
It's Endothermic that parts easy.

endothermic exothermic

(b) Calculate the amount of heat transferred when 50.0 g of CH3OH(g) is decomposed by this reaction at constant pressure.
 _141_kJ

(c) If the enthalpy change of reaction is 10.0 kJ, how many grams of hydrogen gas are produced?
__g
What is the value of ΔH for the reverse of the previous reaction?
__kJ

 (d) How many kilojoules of heat are released when 14.5 g of CO(g) reacts completely with H2(g) to form CH3OH(g) at constant pressure?
__KJ

Offline confusedstud

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Re: Enthalpy help please!!!!
« Reply #1 on: February 25, 2013, 02:09:35 AM »
1 mole of methanol absorbs 90.7kJ so 0.11025 moles absorbs 10kJ. From here is just basic calculations.

If you reverse an endothermic reaction, you get an exothermic reaction. Everything just gets flipped.  And the last question uses this 'flipped' reaction.

Hope this helps. And if I'm not wrong this should be in the high school forum?

Offline I have questions

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Re: Enthalpy help please!!!!
« Reply #2 on: February 25, 2013, 02:20:42 AM »
And if I'm not wrong this should be in the high school forum?

It's Undergraduate General Chemistry I.

Offline confusedstud

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Re: Enthalpy help please!!!!
« Reply #3 on: February 25, 2013, 03:12:41 AM »
Sorry, because I live in Singapore so I'm unfamiliar with the education system in other countries outside of Asia. But did what I say make sense?

Offline I have questions

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Re: Enthalpy help please!!!!
« Reply #4 on: February 25, 2013, 03:42:31 AM »
no, but I figured it out.  I'm offended that they moved this post to highschool chemistry.  it's not highschool chemistry it's college chemistry.  It's CHEM 1211.  WTF?

Offline Borek

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Re: Enthalpy help please!!!!
« Reply #5 on: February 25, 2013, 04:13:15 AM »
The difference between HS and college chemistry - especially in the general chemistry and especially taking into account we have users from different schooling systems - is often blurred. This is a pretty basic question.
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