Question

Marcela dissolves 80.0 g of ammonium nitrate in 50.0 mL of water at room temperature and notes that the temperature of the solution decreases by 5.0°C.
Which correctly designates the signs of changes of G, S and H for this reaction? By changes the symbol is triangle. Please help me!!


A. H>0, S>0 , G<0
B. H<0, S>0 , G<0
C. H>0, S>0 , G>0
D. H<0, S<0 , G>0

Answer 1

Answer:

A. H>0, S>0 , G<0

Explanation:

Hello,

Based on the noticed change in temperature, one can identify that the enthalpy for this dissolution process is positive as long as the temperature decreases, so Δ$H>0$.

Now, due to the fact of the bonds breaking down, one establishes that the entropy increases in a positive way, thus Δ$S>0$.

Finally, by considering that the ammonium nitrate is being dissolved into the water a spontaneous process is carried out, implying that the change in Gibbs free energy turns negative, Δ$G$, so one sum up that the answer is A.

Best regards.

Answer 2

Answer: The correct answer is A

Explanation:

On addition of the ammonium nitrate to 50 ml of water the temperature decreases which means that reaction between the ammonium nitrate and water is an endothermic reaction.The value of $\Delta H$ is positive for an endothermic reactions.

$\Delta H>0$

Entropy is a degree of randomness of the system.

On addition of the ammonium nitrate to water ammonium nitrate break down into ions which means that entropy is increased.

$\Delta S>0$

$\Delta G=\Delta H-T\Delta S$ (Gibb's free energy)

Since, ammonium nitrate is getting dissolved in water which means that this reaction is spontaneous and $\Delta G$ of spontaneous reaction is negative that is:

$\Delta G$