A) 2NO (g) + #O_2# (g) # arr2NO_2# (g)B) #COCl_2# (g) #rarr# CO(g) + #Cl_2# (g)C) #CH_3OH (l) arr# CO(g) + #2H_2# (g)D) #NaClO_3#(s) # arrNa^+# (aq)+#ClO_3^-# (aq)E) no one of the over will show a to decrease in entropy.

You are watching: The system that shows a decrease in entropy (disorder) is


The entropy of a system boosts whenever its particles have more freedom the motion.

Thus, the entropy rises whenever you have much more moles of gaseous products than of reactants and also whenever friend have an ext product particles in solution than you have actually of reactant particles.

Conversely, entropy decreases when you have the the opposite situations.


#"2NO(g)" + "O"_2"(g)" → "2NO"_2"(g)"#

You have 3 mol the gas top top the left and 2 mol ~ above the right, for this reason entropy is decreasing.

This is the correct answer.


#"COCl"_2"(g)" → "CO(g)" + "Cl"_2"(g)"#

You have actually 1 mol that gas on the left and 2 mol of gas ~ above the right, for this reason entropy is increasing.

This answer is incorrect.


#"CH"_3"OH(l)" → "CO(g)" + "2H"_2"(g)"#

This has actually no mole of gas top top the left and 3 mol the gas top top the right, so entropy is increasing.

This prize is incorrect.


#"NaClO"_3"(s)" → "Na"^"+""(aq)" + "ClO"_3^"-""(aq)"#

There are more particles in equipment on the ideal than ~ above the left, for this reason entropy is increasing.

This prize is incorrect.

Answer attach

Apr 28, 2017



A) decrease; much less moles that gas in productB) < no sure, yet it doesn"t seem come have readjusted aside indigenous splitting... Maybe increase? there are much more moles in the product... >C) increase; fluid to gas (wow, it went straight past solid... That"s a many entropy isn"t it?)D) increase; solid come aqueous (gas/liquid distributed in solution)

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Stefan V.
Apr 28, 2017

Here"s what i got.


The general idea right here is the entropy increases as disorder and randomness increase.

Similarly, entropy decreases together disorder and randomness decrease.

Now, randomness and also disorder increase as a problem goes native solid come liquid, and finally come gas. Top top the various other hand, randomness and also disorder decrease as a substance goes from gas come liquid, and also finally come solid.


So best from the start, you know that any type of reaction that has actually a gas as a reactant and also a liquid together a product, because that example, will result in a decrease in entropy.

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In her case, you have

#"CH"_ 3"OH"_ ((l)) -> "CO"_ ((g)) + 2"H"_ (2(g))#

A liquid is being converted to two gases, for this reason entropy will increase.

#"NaClO"_ (3(s)) -> "Na"_ ((aq))^(+) + "ClO"_ (3(aq))^(-)#

A heavy is being liquified to produce solvated ions, so in general, you have the right to say the entropy will certainly increase. This is no a very great example since there are solids that can be liquified in water come a decrease in entropy.

I"m no going to get in why that is the case, simply keep in mind that it is possible.

Now, the first two reactions involve gas reactants and gaseous products. In together cases, look at the total number of moles of gas current on the two sides of the chemistry equation.

When it pertains to reactions that involve gases, you will certainly have

#"more mole of gas top top the reactants" next " -> " to decrease in entropy"##"more mole of gas ~ above the products" side " -> " boost in entropy"#

Notice the this reaction

#2"NO"_ ((g)) + "O"_ (2(g)) -> 2"NO"_ (2(g))#

has a full of #3# moles that gas top top the reactants" side and only #2# moles that gas top top the products" side.