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 above will show a to decrease in entropy.

You are watching: A decrease in entropy is associated with which type of reaction?


The entropy of a system increases whenever its corpuscle have more freedom the motion.

Thus, the entropy increases whenever girlfriend have much more moles that gaseous products than that reactants and whenever you have much more product corpuscle in solution than you have of reactant particles.

Conversely, entropy decreases once you have actually the the opposite situations.


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

You have actually 3 mol of gas on the left and also 2 mol top top the right, so entropy is decreasing.

This is the correct answer.


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

You have 1 mol of gas ~ above the left and 2 mol that gas top top the right, therefore entropy is increasing.

This price is incorrect.


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

This has actually no mole of gas on the left and 3 mol of gas top top the right, for this reason entropy is increasing.

This answer is incorrect.


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

There are much more particles in systems on the appropriate than top top the left, therefore entropy is increasing.

This answer is incorrect.

Answer link

Apr 28, 2017



A) decrease; less moles that gas in productB) < not sure, but it doesn"t seem to have readjusted aside native splitting... Maybe increase? over there are much more moles in the product... >C) increase; fluid to gas (wow, the went straight previous solid... That"s a most entropy isn"t it?)D) increase; solid to aqueous (gas/liquid spread in solution)

Answer connect

Stefan V.
Apr 28, 2017

Here"s what ns got.


The general idea below is the entropy increases together disorder and randomness increase.

Similarly, entropy decreases together disorder and also randomness decrease.

Now, randomness and also disorder boost as a substance goes from solid to liquid, and finally come gas. ~ above the various other hand, randomness and also disorder decrease as a problem goes native gas to liquid, and finally come solid.


So ideal from the start, you know that any reaction that has a gas together a reactant and a liquid together a product, because that example, will an outcome in a decrease in entropy.

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In her case, friend have

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

A liquid is being converted to 2 gases, therefore entropy will increase.

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

A solid is being dissolved to produce solvated ions, for this reason in general, you have the right to say that entropy will increase. This is no a very good example because there room solids that deserve to be dissolved in water come a decrease in entropy.

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

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

When it involves reactions the involve gases, you will have

#"more mole of gas on the reactants" next " -> " to decrease in entropy"##"more moles of gas on the products" next " -> " rise in entropy"#

Notice that this reaction

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

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