Question

For the reaction, NH3(g) + HCl(g) NH4Cl(s) run at 25°C, ΔG = −91368 J and ΔS = −284 J/K. What is the enthalpy change for this reaction?


184,632 J

−91,084 J

−98,468 J

−176,000 J


A negative change in free energy, or −ΔG, represents a spontaneous reaction.

^ this is true

Answer 1

25°C = 298 K
Use
ΔG = ΔH - T ΔS
ΔH= ΔG + TΔS = −91368 + (298)(−284)=−91368-84632=-175730

Therefore ΔH is approx - 176,000 J

Answer 2

A negative change in free energy, or −ΔG, represents a spontaneous reaction.

^ this is true

Answer 3

For a reaction to be spontaneous, ΔG should be negative.
So, now decide yourself :)

Answer 4

oh okay so i am right.

Answer 5

But If a reaction experiences a large decrease in entropy and absorbs a large amount of heat, the reaction will be spontaneous?

Answer 6

most likely it will be non-spontaneous.
However it would be unsafe to comment on this. I would rather use this formula
ΔG = ΔH - T ΔS

and see if ΔG is positive or negative
if ΔG is positive --> non-spontaneous reaction
if ΔG is negative --> spontaneous reaction

Answer 7

okay last one

The free energy of an object is the total available energy that the object possesses.

this is one is false? correct?

Answer 8

Well, can you give me a a better word for free energy

Answer 9

In other words I don't understand the term "free energy" in this context.