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

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

Step-by-step 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<0`, so one sum up that the answer is A.

Best regards.

Answer 2

Answer: The correct answer is A

Step-by-step 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<0`