Question

Can someone check my answers?

Answer 1

Consider the following reaction occurring in a closed chemical system. Assume that this reaction is at equilibrium and that in general the reaction to the right is favored.
CH3CH2OH + 3O2 2CO2 + 3H2O ∆H = –1,235 kJ/mol
• What type of chemical reaction is this?
• If more CH3CH2OH is added to the system, how will the reactions shift to reach equilibrium again?
• If water is extracted from the system, how will the reactions shift to reach equilibrium again?
• If heat is removed from the system, how will the reactions shift to reach equilibrium again?
• What is the name of the principle that helps you predict each of these shifts in equilibrium?

Answer 2

For the first one the reaction is spontaneous

Answer 3

For the third one it will get rid of all the water and find a substitute.

Answer 4

@Frostbite can you help me

Answer 5

Heard about Le Chatelier's principle?

Answer 6

a little but i didnt really get it

Answer 7

Right this what the questions is all about.

Answer 8

But first we need two other words:
Exothermic and endothermic. Heard about these before?

Answer 9

yes

Answer 10

Good. So is the reaction CH3CH2OH + 3O2 -> 2CO2 + 3H2O exothermic or endothermic?
(the first question)

Answer 11

endothermic?

Answer 12

Not quite. Remember the rule:
Exothermic: \(\Delta H<0\)
Endothermic: \(\Delta H>0\)
Try again :)

Answer 13

OH yea so since its greater then 0 its exothermic

Answer 14

Exactly.

Answer 15

Now I fast jump to #5 "What is the name of the principle that helps you predict each of these shifts in equilibrium?"

I gave you the answer (me being stupid)... so what is the answer?

Answer 16

Le Chatelier's principle

Answer 17

Exactly.
Now I like you to try explain #2 and #3 using the principle, if you can handle #4 too, you can try it, otherwise we save it for a little while.

Answer 18

Could you review the principle a little

Answer 19

The principle in a nutshell say: Interference with an equilibrium system promotes changes that diminish the effect of the intervention.

What does this mean and what is the consequence?
If a system is changed in a way that increases the concentration of one of the reacting species, it will favor the reaction in which the increased specie(s) is consumed. This principle also applies to pressure and heat.

\[\Large Q=\frac{ [\textrm{CO}_{2}]^2 \times [\textrm{H}_2\textrm{O}]^3 }{ [\textrm{CH}_{3}\textrm{CH}_{2}\textrm{OH}] \times [\textrm{O}_{2}]^3 }\]

Answer 20

For the second one wont it shift up

Answer 21

Are you sure? If you add more ethanol (CH3CH2OH). Look at what I wrote:
"If a system is changed in a way that increases the concentration of one of the reacting species, it will favor the reaction in which the increased specie(s) is consumed."
We add ethanol, so what happens with it?

Answer 22

What way do we push the reaction?

Answer 23

down

Answer 24

You mean towards H2O and CO2?

Answer 25

yes

Answer 26

Exactly! :)
What about #3 then? Now we REMOVE water.

Answer 27

it would to towards the other side right

Answer 28

You mean towards H2O and CO2 (just asking to be sure)?

Answer 29

No towards the CH3CH2OH
+
O2

Answer 30

Ahhhh, this time we don't add water, but we remove it, meaning that we like more water created to create equilibrium. So it would be the other way around. You see that?

Answer 31

Oh okay

Answer 32

:) nearly in house. The last one is a bit tricky, but I will allow you to guess there are 50/50 chance and I help by saying it relates to the reaction being exothermic.

Answer 33

the heat would find a release point

Answer 34

I try help you a bit.

In an exothermic reaction, the system gives energy as heat to the surroundings. If we now add heat to the system by rising the temperature, the equilibrium is shifted towards the reactants.

Can you guess the answer now?

Answer 35

the head would spread out in the equation

Answer 36

It would push it towards the products (H2O and CO2).

I can see Le Chatelier's principle indeed are causing some problems.

May I suggest you read the following link:
http://chemwiki.ucdavis.edu/Physical_Chemistry/Equilibria/Le_Chatelier's_Principle
Perhaps it can help you to a better understanding. Still I like to help you, all you gotta do is to message me.

Answer 37

Okay Ill chekc it out thanks

Answer 38

No problems at all. Best of luck with everything, if you are having problems, don't hesitate writing to me.